ClinGen
Cystic fibrosis (CF) is an autosomal recessive disease. Assuming a carrier frequency of 1 in 25 (4%) in the general population, what is the probability of a CF carrier having an affected child with an unaffected mate of unknown CF carrier status? 25% 16% 4% 1% 0.25%
1%
Match the genetic syndrome to the associated phenotypic features: Congenital heart defects (tetrology of Fallot), cleft palate, hypo-parathyroidism, immune deficiency (due to thymic aplasia), psychiatric problems 22q11 deletion syndrome Cri du Chat syndrome Klinefelter syndrome Trisomy 13 Trisomy 18 Trisomy 21 Turner Syndrome Williams syndrome
22q11 deletion syndrome
A gene with 25 introns has how many exons (ignoring any alternative splicing)? 25 26 24 27 23
26
What is present in the first exon of all pre-mRNAs? 3' splice site 3'-UTR 5'-UTR Start codon Stop codon
5'-UTR
Xeroderma pigmentosum (XP) is an autosomal recessive disease. What is the expected frequency of children affected with XP born to a woman homozygous for disease mutations in the XPA gene and a man homozygous for disease mutations in the XPB gene? 100% 75% 50% 25% <1%
<1%
A couple has a child with spina bifida and is counseled (correctly) that the chance their second child will have spina bifida is approximately 3%. They go on to have a second child who does, in fact, have spina bifida. Both children are evaluated by a medical geneticist and undergo comprehensive testing which rules out all known syndromic, teratogenic, chromosomal and single gene causes of spina bifida. If they go on to have a 3rd child, the chance that child will have spina bifida is: 0 3% >3% but <25% <3% 50%
>3% but <25%
Which of the following polymorphisms is most likely to result in rapid metabolism? An alteration in the TATA box of the promoter that lead to decreased mRNA for a gene encoding for a phase II enzyme. A copy number variant resulting in deletion of a gene that encodes for an enzyme involved in phase II metabolism. A copy number variant resulting in duplication of a gene that encodes for an enzyme involved in phase I metabolism. A frameshift mutation in a gene encoding for an enzyme involved in phase II metabolism. A missense mutation leading to decreased stability in an enzyme required for phase I metabolism.
A copy number variant resulting in duplication of a gene that encodes for an enzyme involved in phase I metabolism.
What would be the expected effect on beta-globin gene expression of replacing the beta-globin 3'-UTR with the 3'-UTR from the Fos mRNA? A decrease in the amount of beta-globin protein produced. An increase in the amount of beta-globin protein produced. A decrease in transcription of the beta-globin gene. A change in the splicing pattern of beta-globin pre-mRNA. No change in beta-globin gene expression.
A decrease in the amount of beta-globin protein produced.
An autosomal recessive disorder is caused by defective gene expression from gene Z. If gene Z is maternally imprinted (and this completely inhibits expression of gene Z), the disorder would LEAST likely be associated with which of the following situations: A missense mutation in the maternal copy of gene Z only Maternal uniparental disomy of the chromosome (2 copies of the mother's chromosome) carrying gene Z Microdeletion of the paternal copy of gene Z A mutation in an imprinting center in the paternal chromosomal region near gene Z
A missense mutation in the maternal copy of gene Z only
In the FMR1 gene, pre-mutation alleles have 59-200 repeats. Which statement about Fragile X syndrome is true: A father with a 180 CGG repeats in his FMR1 gene has an increased risk of having a boy with intellectual disability. A father with a 35 CGG repeats in his FMR1 gene has an increased risk of having a grandchild with intellectual disability. A mother with a 35 CGG repeat in one of her FMR1 genes and 10 CGG repeats in her other FMR1 gene is likely to have a son with 270 CGG repeats in his FMR1 gene. A mother with 35 CGG repeats in one of her FMR1 genes and 10 CGG repeats in her other FMR1 gene has an increased risk of developing Fragile X related premature ovarian failure (POI). A mother with 35 CGG repeats in one of her FMR1 genes and 180 CGG repeats in her other FMR1 gene has an increased risk of having a child with intellectual disability.
A mother with 35 CGG repeats in one of her FMR1 genes and 180 CGG repeats in her other FMR1 gene has an increased risk of having a child with intellectual disability.
A dAMP residue in the non-template DNA strand of a gene would correspond to what nucleotide residue at the equivalent position of the RNA transcript of that gene? AMP CMP GMP TMP UMP
AMP
Given the parental Chromosome 1 haplotypes "ABCDE" and "abcde", and assuming that the loci are in alphabetical order on the chromosome and each locus is 1 centiMorgan away from the next, which is the least likely recombinant haplotype? ABcde abCDE ABCDe AbcdE Abcde
AbcdE
Which of the following processing steps occurs first in the maturation of a pre-mRNA to an mRNA? Addition of a poly(A) tail Removal of introns (splicing) Transport to the cytoplasm Addition of a 7-methylguanosine cap Cleavage at the poly(A) site
Addition of a 7-methylguanosine cap
Match the following terms form the best match? People with a NF-1 mutation can exhibit no signs of neurofibromatosis at a young age Age-dependant penetrance Allelic heterogeneity Locus heterogeneity Pleiotropy Variable expression
Age-dependant penetrance
Match the following terms form the best match? Cystic fibrosis can be caused by a variety of mutations in the CFTR gene. Age-dependant penetrance Allelic heterogeneity Locus heterogeneity Pleiotropy Variable expression
Allelic heterogeneity
What is the mechanism for production of different forms of alpha-tropomyosin in srtiated and smooth muscle? Transcription of different alpha-tropomyosin genes in striated and smooth muscle Alternative splicing of alpha-tropomyosin pre-mRNA in striated and smooth muscle Editing of the alpha-tropomyosin mRNA in the striated muscle to create an early stop codon Proteolysis of alpha-tropomyosin in the striated muscle to create a truncated protein
Alternative splicing of alpha-tropomyosin pre-mRNA in striated and smooth muscle
Which is the best method for detecting a 100 kb deletion whose position in the genome is unknown? Array comparative genomic hybridization (aCGH) Chromosome painting (also called a spectral karyotype) Sanger sequencing Genomic PCR Single-gene fluorescence in situ hybridization (FISH)
Array comparative genomic hybridization (aCGH)
What is one mechanism by which the anti-cancer drug 5-fluorouracil inhibits DNA synthesis? By acting as an irreversible inhibitor of DNA polymerase By blocking the conversion of NDPs to dNDPs By blocking the relaxation of supercoiled DNA ahead of the replication fork By blocking the unwinding of chromosomal DNA by DNA helicase By blocking the synthesis of dTMP from dUMP
By blocking the synthesis of dTMP from dUMP
Which one of the following cis-acting elements mediates the activation of genes in response to an increase in the intracellular concentration of cyclic AMP (cAMP)? GRE CRE AP-1 site TATA box start codon
CRE
Which factor promotes exon definition only for the first exon of a multi-exon pre-mRNA? SR proteins Poly(A)-binding proteins hnRNP proteins U2 snRNP Cap-binding complex
Cap-binding complex
Which is TRUE of female carriers of X-linked recessive disorders? Abnormalities of the X-chromosome (deletions, translocations) have NO effect on the distribution of X-inactivation in tissues Carrier effects seen in X-linked disorders are related to skewing of X-inactivation in important tissues Male offspring of a carrier of an X-linked recessive disorder have a 25% chance of being affected Female carriers of X-linked recessive disorders are NOT at risk of developing health problems related to the disorder they carry
Carrier effects seen in X-linked disorders are related to skewing of X-inactivation in important tissues
Which one of the following properties of RNA polymerases is shared with DNA polymerases? Uses ribonucleoside triphosphates as a substrate Does not require a primer to initiate strand synthesis Does not require a helicase once strand synthesis has begun Catalyzes bond formation between 3' oxygen and alpha phosphorus atoms Re-anneals separated DNA strands within the active site cleft
Catalyzes bond formation between 3' oxygen and alpha phosphorus atoms
AGG repeats in the 5' UTR of the FMR1 gene serve to "anchor" DNA polymerase I and prevent slipped mispairing. Recent literature suggests that patients with a higher number of AGG repeats dispersed throughout a CGG premutation are less likely to have expansion to a full mutation occur. AGG repeats in FMR1 is an example of which of the following concepts? Trans acting elements Promoters Cis acting elements Enhancers Mutagens
Cis acting elements
Match the genetic syndrome to the associated phenotypic features: Microcephaly (small head size), mental retardation, high pitched cry 22q11 deletion syndrome Cri du Chat syndrome Klinefelter syndrome Trisomy 13 Trisomy 18 Trisomy 21 Turner Syndrome Williams syndrome
Cri du Chat syndrome
Unequal meiotic recombination requires the mis-pairing of nearly identical sequences during the synapsis of homologous chromatids, and which of the following additional events? Crossover within the mis-paired sequences Crossover within the unpaired "looped-out" sequences Crossover within the flanking correctly paired sequences Gene conversion between the mis-paired sequences Gene conversion between the "looped-out" sequences
Crossover within the mis-paired sequences
A splice site that is used by the spliceosome only when a constitutive splice site is mutated is called what? Alternative splice site Branchpoint ATAC splice site Cryptic splice site Polypyrimidine stretch
Cryptic splice site
Which enzyme is required to seal a nick (broken phosphoester bond) in a DNA strand? DNA polymerase DNA exonuclease DNA ligase DNA helicase DNA endonuclease
DNA ligase
Which one of the following DNA repair pathways specializes in correcting errors made by DNA polymerase? DNA mismatch repair Nucleotide excision repair Double strand break repair Non-allelic homologous recombination Non-homologous end joining
DNA mismatch repair
Which enzyme is required to fill in a single-stranded gap in double-stranded DNA? DNA polymerase DNA exonuclease DNA ligase DNA helicase DNA endonuclease
DNA polymerase
Which one of the following enzymes is many times more active in lagging strand DNA synthesis than in leading strand DNA synthesis? DNA helicase DNA polymerase DNA primase DNA topoisomerase pyrophosphatase
DNA primase
Which one of the following is the direct target of the enzymatic activity of diphtheria toxin? Peptidyl transferase site of the large ribosomal subunit Decoding site of the small ribosomal subunit Initiator methionyl-tRNAMeti EF-1alpha EF-2
EF-2
Which one of the following proteins is inactivated by ADP-ribosylation catalyzed by diphtheria toxin? cap-binding protein poly(A)-binding protein Release factor EF-1alpha EF-2
EF-2
When is the genomic imprint of an imprinted gene "erased" (removed)? Fertilization Early in embryogenesis Late in embryogenesis Early in gametogenesis Late in gametogenesis
Early in gametogenesis
Which cellular process most often results in the conversion of DNA damage into a mutation? Apoptosis DNA polymerase arrest DNA repair Error-free DNA polymerase bypass Error-prone DNA polymerase bypass
Error-prone DNA polymerase bypass
Animal studies comprise a significant portion of the evidence base for the risks associated with exposure to teratogens during pregnancy. Which of the following best describes the value of animal studies in this context? They provide a way to more precisely determine the human dosage threshold Genetic background and other factors such as diet can be tightly controlled They are used to study individual differences in susceptibility to a given teratogen The period of greatest vulnerability to the effects of teratogens is longer than it is in humans
Genetic background and other factors such as diet can be tightly controlled
Which trans-acting factor best fits the following description: a tissue-specific gene regulatory protein of the nuclear receptor class? Androgen receptor TFIIB CREB Jun/Fos HNF-4alpha
HNF-4alpha
Match the clinical situation to the most appropriate genetic test. Use each test once. Recurrent Pregnancy Loss Locus specific FISH Microarray CGH High Resolution Karyotype
High Resolution Karyotype
Which of the following proteins is not a component of the histone octamer around which DNA is wrapped in a nucleosome? Histone H1 Histone H2A Histone H2B Histone H3 Histone H4
Histone H1
Which of the following does NOT have a multifactorial inheritance pattern: Manic depressive illness Spina bifida Congenital heart disease Huntington disease Asthma
Huntington disease
A six-year-old boy is brought to your clinic by his foster parents because he is misbehaving at school and having difficulty learning. The social worker told them that he was recently removed from his birth mother's care because she was struggling with alcoholism and neglecting the child. The foster parents are concerned that he might have fetal alcohol syndrome (FAS). They have no information about the birth mother's use of alcohol during the pregnancy. He is a bit small for his age but has no craniofacial features of FAS. What can you tell the foster parents (or social worker)? He must have FAS because there is no other reason for him to have growth, behavioral and learning difficulties. If his mother drank alcohol only late in the pregnancy it's possible that he could have growth and CNS effects without facial features. Since he has normal facial features he has not been affected by alcohol exposure. There is no way to address this question unless the birth mother admits to drinking significant amounts of alcohol during the pregnancy.
If his mother drank alcohol only late in the pregnancy it's possible that he could have growth and CNS effects without facial features.
If you wanted expression of a protein to decrease when intracellular iron levels are low, where in its gene would you insert the DNA sequence coding for an iron responsive element (IRE)? In the promoter region, upstream of the transcription start site In the 5'-UTR, between the transcription start site and start codon In the middle of an intron, away from the 5' and 3' splice sites In the 3'-UTR, between the stop codon and the poly(A) site A few hundred base pairs downstream of the poly(A) site
In the 5'-UTR, between the transcription start site and start codon
You are ordering genetic testing for your patient, which requires a specific primer. The primer has a known tendency to bind to similar, but undesired locations in the DNA. In order to help ensure this primer binds to the correct location, what might you do during the preparation? Increase the temperature during the reannealing process Decrease the temperature during the denaturing process Increase the salt concentration during the denaturing process Increase the amount of primer available Increase the amount of time the primer has to renneal
Increase the temperature during the reannealing process
What is thought to be the mechanism of immunosuppression by the drug mycophenolic acid? Inhibition of the conversion of IMP to GMP by IMPDH. Inhibition of the conversion of IMP to AMP by IMPDH Inhibition of the conversion of guanine to GMP by HGPRT. hibition of the conversion of NMPs to dNMPs by ribonucleotide reductase. Inhibition of the conversion of NDPs to dNDPs by ribonucleotide reductase.
Inhibition of the conversion of IMP to GMP by IMPDH.
Which property is common to both a restriction enzyme and CRISPR-Cas9? Its sequence specificity can be predictably altered by mutation It contains RNA as an essential component It has double-stranded DNA endonuclease activity It commonly has a 4 to 8 base pair recognition sequence It tends to recognize palindromic sequences
It has double-stranded DNA endonuclease activity
Match the genetic syndrome to the associated phenotypic features: Tall stature, infertility and normal intelligence 22q11 deletion syndrome Cri du Chat syndrome Klinefelter syndrome Trisomy 13 Trisomy 18 Trisomy 21 Turner Syndrome Williams syndrome
Klinefelter syndrome
What disease is caused by a single inactivating mutation in the X-linked HGPRT gene? Gout Severe combined immunodeficiency disease Lesch-Nyhan syndrome HNPCC Xeroderma pigmentosa
Lesch-Nyhan syndrome
What is the probability of a carrier of cystic fibrosis (an autosomal recessive disorder) and a non-carrier (homozygous normal) individual having a child that is affected with cystic fibrosis? Less than 1% 25% 50% 75% 100%
Less than 1%
Match the following terms form the best match? Thalassemias can be caused by mutations in either the alpha globin or beta globin genes. Age-dependant penetrance Allelic heterogeneity Locus heterogeneity Pleiotropy Variable expression
Locus heterogeneity
Match the clinical situation to the most appropriate genetic test. Use each test once. Clinical suspicion of Williams syndrome Locus specific FISH Microarray CGH High Resolution Karyotype
Locus specific FISH
Acetylation and methylation of which amino acid residue in histone N-terminal tails has the greatest influence on chromatin structure and gene expression? Lysine (K) Arginine (R) Serine (S) Threonine (T) Histidine (H)
Lysine (K)
Which one of the following posttranslational modifications of histone N-terminal "tails" is most often associated with gene activation? Lysine methylation Lysine phosphorylation Lysine acetylation Lysine hydroxylation Lysine transglutamination
Lysine acetylation
DNA replication can result in hemi-methylated DNA. Which enzyme restores symmetric methylation of CpG dinucleotides present in both strands of DNA after DNA replication? Histone methyltransferases Thymidylate synthase Ribonucleotide reductase Histone deacetylases Maintenance DNA methyltransferases
Maintenance DNA methyltransferases
When methylated DNA strands are separated during DNA replication, what enzyme ensures the new DNA is properly methylated? Rev1 Cytosine methyltransferase Histone methyltransferase Histone acetyltransferase Maintenance methyltransferase
Maintenance methyltransferase
Which one of the following correctly characterizes post-transcriptional gene regulation? Occurs at the earliest step of the gene expression pathway Occurs only in the cell nucleus Primarily uses DNA-binding proteins Mediates rapid responses to changes in the cellular environment Is the major function of nuclear receptors
Mediates rapid responses to changes in the cellular environment
Match the clinical situation to the most appropriate genetic test. Use each test once. Mental retardation and multiple congenital anomalies Locus specific FISH Microarray CGH High Resolution Karyotype
Microarray CGH
What is the expected direct consequence of a mutation in the gene for an aminoacyl-tRNA synthetase that disrupts only the proofreading activity of the enzyme? Accumulation of additional mutations in the genome Synthesis of prematurely terminated proteins Decreased production of protein due to mRNA degradation Mis-incorporation of amino acids into proteins Defects in pre-mRNA splicing
Mis-incorporation of amino acids into proteins
A genetic test for Angelman Syndrome detects the methylation pattern in the 15q11-13 region. It can detect all of the causes of Angelman Syndrome EXCEPT (Hint- most of the cases are caused by maternal 15q11-13 deletions): Maternal 15q11-13 deletions Paternal uniparental disomy (UPD) Mutations in the maternal copy of the gene for E6-AP ubiquitin-protein ligase (UBE3A) Imprinting center mutations
Mutations in the maternal copy of the gene for E6-AP ubiquitin-protein ligase (UBE3A)
A developmentally normal 3 year old girl is found to have easy bruising and bleeding. Her father is known to have Hemophilia A, which is an X-linked recessive disorder. Her mother is known to carry an Xp11.3 deletion but is unaffected. The mother has 2 brothers with mental retardation. On testing the girl is found to be factor VIII deficient (consistent with hemophilia A). What explains the occurrence of an X-linked disorder in this female? Random but unfavorable X inactivation in the liver resulted in skewing towards the paternal X chromosome. Nonrandom X inactivation due to the presence of a deletion on the maternal X chromosome led to skewing towards the paternal X chromosome. A de novo mutation occurred in the maternal allele so that both the maternal and paternal copies of the Factor VIII gene were inactive. The mother has germline mosaicism for the Factor VIII mutation
Nonrandom X inactivation due to the presence of a deletion on the maternal X chromosome led to skewing towards the paternal X chromosome.
A substitution mutation in the protein-coding region of a gene that changes a leucine codon to a stop codon is best described as which type of mutation? Missense Nonsense Frameshift Antisense Deletion
Nonsense
What is the process by which intron inclusion can result in decreased levels of an mRNA? Transcription termination Nonsense-mediated decay Cleavage and polyadenylation Genomic imprinting Histone methylation
Nonsense-mediated decay
Which is the best definition for genomic imprinting? Parent-of-origin differences in the level of expression of a given allele Random inactivation of an X chromosome in females Post-translational modification of amino acid residues in histone N-terminal tails Silencing of a gene during development Hybridization of different colored probes along the length of each chromosome
Parent-of-origin differences in the level of expression of a given allele
If I would tell you that a new disorder called Brow's Disease has variable expressivity, locus homogeneity, allelic heterogeneity, and pleiotrophic effects, how would you explain these terms to a patient that you recently diagnosed with it? Pick the ONE best answer below. Patients have a single clinical problem and some patients are worse off than others. All patients have mutations in the same gene but different types of mutations. Patients have several different clinical problems and some patients are worse off than others. All patients have mutations in the same gene but different types of mutations. Patients have several different clinical problems but have very similar course of disease. All patients have mutations in the same gene but different types of mutations. Patients have one clinical problem and some patients are worse off than others. All patients have mutations in different genes and different types of mutations.
Patients have several different clinical problems and some patients are worse off than others. All patients have mutations in the same gene but different types of mutations.
Match the following terms form the best match? Patients with cystic fibrosis can have pulmonary, pancreatic and fertility problems. Age-dependant penetrance Allelic heterogeneity Locus heterogeneity Pleiotropy Variable expression
Pleiotropy
Fragile X tremor ataxia syndrome (FXTAS) is caused by which mechanism? Methylation of the FMR1 promoter leads to repression on translation of the gene. Loss of function of FMRP RNA mediated toxicity Haploinsufficiency Dominant Negative Effect
RNA mediated toxicity
Transcription of Fos, a proto-oncogene, is highly regulated through degradation. What is the first the step in degrading this mRNA transcript? Decapping of the mRNA transcript Binding of the poly(A) binding protein Removal of the poly(A) tail by deadenylase Editing of Fos transcript to create an early stop codon Alternative splicing of Fos to an inactive form
Removal of the poly(A) tail by deadenylase
Methylation of cytosine residues in CpG dinucleotide sequences in DNA is most commonly associated with what effect in human cells? Repression of transcription of the adjacent gene Activation of transcription of the adjacent gene Enhancement of meiotic recombination Stimulation of DNA repair Initiation of DNA replication
Repression of transcription of the adjacent gene
An 8 month old has 10 café au lait spots (greater than 5mm) and faint freckles in her axilla. Which of the following is TRUE? She must have NF1 molecular testing to confirm the diagnosis of neurofibromatosis type 1 (NF-1) She meets clinical criteria and therefore has NF-1 She would meet criteria if she was found to have Lisch nodules on slit lamp exam of the eye Her parents are carriers and are therefore not at risk Her parents risk for future pregnancies is 25%
She meets clinical criteria and therefore has NF-1
Which of the following are the 3 cardinal morphologic features of fetal alcohol syndrome? Short palpebral fissures, flat philtrum and thin upper lip Long palpebral fissures, congenital heart defect, and renal malformations Preauricular pits, epicanthic folds, and narrow palate Supernumerary nipples, syndactyly and cleft palate
Short palpebral fissures, flat philtrum and thin upper lip
Which are most similar in sequence? Human chromosomes 21 and 22 The X and Y chromosomes Chromosomes 2 of chimpanzee and humans Homologous chromatids of human chromosome 21 Sister chromatids of human chromosome 21
Sister chromatids of human chromosome 21
Myotonic dystrophy is an autosomal dominant disorder caused by an expansion of CTG repeats in the 3' UTR of the DMPK gene. A three generation family shows "anticipation" with the grandchild having worse disease than the mother who in turn has worse disease than the grandmother. A Southern blot would likely show that the DNA fragment containing the 3' UTR expansion is: Greatest in the grandmother and smallest in the grandchild Greatest in the grandmother and smallest in the mother Smallest in the grandmother and greatest in the grandchild Missing in the grandmother Missing in the mother
Smallest in the grandmother and greatest in the grandchild
Steroid hormones such as cortisol tend to be slow-acting (hours to days) relative to other small molecule effectors, such as epinephrine (adrenaline), which can have effects in seconds or minutes. What property of steroid action best explains this slow action? Steroids act on transcription, so it takes a long time for protein levels to change. Steroids act through a "kinase cascade" that takes hours to complete. Steroids act through a second messenger, production of which is slow. Steroid receptors are not produced until steroids are present. Uptake of steroids into cells is slow.
Steroids act on transcription, so it takes a long time for protein levels to change.
In order for transcription to occur, TFIID binds to what cis-acting element? TATA box RNA polymerase Initiation site GRE An enhancer
TATA box
Which one of the following cis-acting elements is bound by the general transcription factor TFIID? GRE CRE AP-1 site TATA box start codon
TATA box
Which enzyme contains an RNA subunit that acts as a template for DNA synthesis at the ends of chromosomes? RNA polymerase DNA topoisomerase DNA primase DNA helicase Telomerase
Telomerase
What recognizes the 5' splice site sequence of an intron to initiate spliceosome assembly? Sequence-specific RNA binding proteins associated with the CTD of RNA polymerase II The U1 snRNA component of the U1 snRNP, by direct base-pairing Cleavage and polyadenylation factors The initiator methionyl-tRNAMeti bound to the small ribosomal subunit The U2 snRNA component of the U2 snRNP, by direct base-pairing
The U1 snRNA component of the U1 snRNP, by direct base-pairing
A 23-year-old woman has just discovered that she is 14 weeks pregnant (post conception). At her first visit with her obstetrician today, she was told of the risks associated with drinking alcohol during pregnancy. Now she is concerned because she had 4 drinks at a wedding reception 13 weeks ago. She has had no alcohol since. Which of the following would be the most appropriate information to give her? She doesn't have to worry because consumption of 4 alcoholic drinks is not enough to have significant effects. The chance that the child will have fetal alcohol syndrome is low because the exposure occurred during the "all or none" period. In a few weeks, an ultrasound can be done; if it shows normal fetal growth, she can be reassured based on this alone The risk depends on whether she drank beer, wine, or mixed drinks.
The chance that the child will have fetal alcohol syndrome is low because the exposure occurred during the "all or none" period.
A child is born with the features of Down syndrome. Karyotype shows an unbalanced 14:21 Robertsonian translocation as the cause. Parental karyotypes reveal that the mother is the carrier of balanced 14:21 Robertsonian translocation. The father has a normal karyotype. Which of the following is TRUE? If the father was the one who carried the translocation, the recurrence risk would be higher. In children with an unbalanced Robertsonian translocation, one of the parents is always a carrier The mother has a 10% chance of having another child with Down syndrome due to this translocation. The mother is at increased risk (over the general population) of having a child with other trisomies (trisomy 18 or 13).
The mother has a 10% chance of having another child with Down syndrome due to this translocation.
The degree of linkage between two genes on the same chromosome correlates best with which property? The number of DNA base pairs between the two genes The similarity of the proteins encoded by the two genes The similarity of the nucleotide sequence of the two genes The average distance of the two genes from the centromere The presence of a disease mutation in one of the genes
The number of DNA base pairs between the two genes
What is the best explanation as to why Becker patients have a milder phenotype than Duchenne patients? They have deletions of smaller exons that encode the rod domain They have deletions of larger exons that encode the rod domain Their deletions only occur outside of the rod dystrophin domain. Their deletion within the rod domain are in-frame Their deletions within the rod domain are out-of-frame
Their deletion within the rod domain are in-frame
Which of the following is true regarding the effects of prenatal alcohol exposure? Fetal alcohol syndrome can be caused by alcohol consumption by the mother OR father. A pregnant woman can drink alcohol and avoid having a child with FAS as long as she consumes less than 3 standardized alcoholic beverages per day There is no amount of alcohol intake during pregnancy that has been proven to be safe for the developing embryo and fetus The teratogenic effects of alcohol have been widely recognized by the medical community for several centuries.
There is no amount of alcohol intake during pregnancy that has been proven to be safe for the developing embryo and fetus
An 8 year old girl has neurofibromas and café au lait spots isolated to her left leg. Which of the follow is FALSE? This is the most common presentation of neurofibromatosis type 1 This is called segmental NF-1 and is an example of somatic mosaicism This is due to a post-zygotic de novo mutation in the NF1 gene which occurred after the first cell division. The child is only at risk of passing on this mutation to her offspring if the mutation also segregated to her germline and if she does pass on the mutation her child will have typical NF-1. The child's parents have a recurrence risk equal to the population baseline for NF-1.
This is the most common presentation of neurofibromatosis type 1
It is generally believed that the molecular pathogenesis of Huntington disease (due to CAG repeats, codon specifying the amino acid glutamine, in the coding region of the Huntingin gene) involves: Imprinting Transcriptional repression Toxic effect of the mutated Huntingtin protein Action of an abnormal mRNA containing the triplet repeat CAG A Huntingtin mRNA splicing defect
Toxic effect of the mutated Huntingtin protein
Which of the following is the most downstream (3') feature of a gene? Translation stop codon Transcription termination site Poly(A) site Poly(A) signal 3'-untranslated region (3'-UTR)
Transcription termination site
Synthesis of which one of the following proteins increases when intracellular iron levels are low? Cytosolic aconitase DMT1 Ferritin Transferrin Transferrin receptor
Transferrin receptor
Binding of iron regulatory protein 1 (IRP1) to the iron-responsive element (IRE) in the 5'-UTR of the ferritin mRNA blocks which step in ferritin gene expression? Capping of the ferritin pre-mRNA Degradation of the ferritin mRNA Splicing of the ferritin mRNA Transcription of the ferritin gene Translation of the ferritin mRNA
Translation of the ferritin mRNA
Match the genetic syndrome to the associated phenotypic features: Hypotelorism (narrowly spaced eyes), microphthalmia (small eyes), midline facial clefts, polydactyly (extra fingers), scalp defects (cutis aplasia), holoprosencephaly (severe brain anomaly), early death 22q11 deletion syndrome Cri du Chat syndrome Klinefelter syndrome Trisomy 13 Trisomy 18 Trisomy 21 Turner Syndrome Williams syndrome
Trisomy 13
Match the genetic syndrome to the associated phenotypic features: Small for gestational age, clenched hands with overlapping fingers, congenital heart disease, severe feeding problems, rocker bottom feet, early death 22q11 deletion syndrome Cri du Chat syndrome Klinefelter syndrome Trisomy 13 Trisomy 18 Trisomy 21 Turner Syndrome Williams syndrome
Trisomy 18
Match the genetic syndrome to the associated phenotypic features: Short stature, nuchal skin redundancy, puffy hands and feet, broad chest, kidney abnormalities,coarctation of aorta, normal intellegence, infertility 22q11 deletion syndrome Cri du Chat syndrome Klinefelter syndrome Trisomy 13 Trisomy 18 Trisomy 21 Turner Syndrome Williams syndrome
Turner Syndrome
Match the following terms form the best match? Some patients with sickle cell disease have many more vaso-occlusive crises than others Age-dependant penetrance Allelic heterogeneity Locus heterogeneity Pleiotropy Variable expression
Variable expression
Match the genetic syndrome to the associated phenotypic features: Mild growth retardation, cognitive disability with high verbal scores, supravalvular aortic stenosis (SVAS), outgoing personality 22q11 deletion syndrome Cri du Chat syndrome Klinefelter syndrome Trisomy 13 Trisomy 18 Trisomy 21 Turner Syndrome Williams syndrome
Williams syndrome
Which one of the following cis-acting elements would you expect to find in the promoter of a gene that is transcribed at a much higher level in males after puberty than before puberty? androgen response element cyclic AMP response element estrogen response element glucocorticoid response element iron response element
androgen response element
A specialized DNA polymerase called Rev1 inserts a dCMP residue across from a missing base in the template strand. What type of DNA damage does Rev1 bypass? deamination thymine dimers DNA polymerase errors double strand breaks depurination
depurination
The ratio of male to female children with pyloric stenosis is 5:1. If a couple has a daughter with pyloric stenosis, the chance that their second child will also have pyloric stenosis is: greater if the second child is a daughter rather than a son greater than it would be if the first child had been an affected son the same regardless of the sex of the first child the same regardless of the sex of the second child
greater than it would be if the first child had been an affected son
Some missense mutations in human glycyl-tRNA synthetase result in autosomal dominant peripheral neuropathies, characterized by impaired motor function and sensory loss in the extremities. Which of the following biochemical defects is most likely to be a direct result of such mutations? increased misincorporation of amino acids during protein synthesis increased mutation rate of genomic DNA inaccurate codon-anticodon pairing in the small ribosomal subunit decrease in nonsense-mediated decay of mRNAs failure to terminate translation properly, resulting in extended proteins
increased misincorporation of amino acids during protein synthesis
5-fluorouracil (5-FU) is used to treat certain cancers. It must be converted to its active form, 5-fluoro-dUMP, in the body. Which one of the following enzymes uses 5-FU as a substrate in the first step of this conversion? dUTPase nucleotide kinase pyrimidine phosphoribosyl transferase (PyPRT) ribonucleotide reductase thymidylate synthase
ribonucleotide reductase
For which enzyme is 5-fluoro-dUMP an irreversible inhibitor? dUTPase nucleotide kinase pyrimidine phosphoribosyl transferase (PyPRT) ribonucleotide reductase thymidylate synthase
thymidylate synthase
What type of DNA damage is most often induced by UV light? adenine dimer abasic site thymine dimer double strand breaks deamination
thymine dimer
A large pedigree in which only males are affected with an inherited disease, and in which affected individuals don't have affected parents, is most consistent with which type of inheritance? autosomal recessive autosomal dominant x-linked recessive x-linked dominant x-inactivation
x-linked recessive
Activity of which one of the following enzymes typically prevents purine base salvage? adenosine deaminase nuceloside phosphorylase xanthine oxidase HGPRT nucleotide phosphatase
xanthine oxidase
Allopurinol's efficacy in treating gout is thought to be due to its inhibition of which one of the following enzymes? adenosine deaminase xanthine oxidase hypoxanthine-guanine phosphoribosyl transferase (HGPRT) inosine monophosphate dehydrogenase (IMPDH) guanase
xanthine oxidase
