NUR 4125 PrepU Chapter 5

The criteria for fetal alcohol syndrome diagnosis require the documented presence of all of the following except which one?

An absence of all or part of the X chromosome Explanation: An absence of all or part of the X chromosome is seen in Turner syndrome. The other options are criteria for fetal alcohol syndrome diagnosis.

A nurse notes that a client with neurofibromatosis has eight flat, cutaneous, light brown spots (2 cm in diameter each) over the trunk area. The nurse documents these as being:

Cafe au lait spots Explanation: The nurse should document the light brown, flat, cutaneous spots as being cafe au lait spots.

Which disease is caused by a genetic defect of chloride transport?

Cystic fibrosis Explanation: Cystic fibrosis is a single-gene inheritance disorder of membrane transport of chloride ions in exocrine glands, causing lung and pancreatic disease. The other options are also single-gene inheritance disorders but do not involve chloride transport.

Mendelian inheritance characteristics are most closely associated with which one of the following?

Marfan syndrome Explanation: Marfan syndrome is an autosomal dominant disorder caused by a mutant allele at a single gene locus and follows Mendelian patterns of inheritance. Congenital heart disease and diabetes mellitus are multifactorial inheritance disorders. Turner syndrome is a chromosomal disorder.

A pregnant client is concerned about her baby having abnormal thyroid function since it "runs in the family." The nurse advises the client to avoid exposure to which teratogenic agent?

Radioactive iodine Explanation: Administration of therapeutic doses of radioactive iodine (131I) during the 13th week of gestation, the time when the fetal thyroid is beginning to concentrate iodine, has been shown to interfere with thyroid development.

The parents of an infant boy ask the nurse why their son was born with a cleft lip and palate. The nurse responds that cleft lip and palate are defects that are caused by many factors. The defect may also be caused by teratogens. Which teratogens can cause cleft lip and palate?

Rubella Explanation: This defect may be caused by the teratogen rubella and is often encountered in children with chromosomal abnormalities.

After attending a preconception workshop, a young woman asks the educator to explain neural tube defects (NTD). Which conditions are examples of neural tube defects? Select all that apply. Encephalocele Cleft palate Anencephaly Heart defects Spina bifida

Spina bifida Anencephaly Encephalocele Explanation: Folic acid deficiency has been implicated in the development of neural tube defects (e.g., anencephaly, spina bifida, encephalocele). Cleft palate and heart defects are not associated with neural tube defects.

Which condition follows a Mendelian pattern of recessive inheritance?

Tay-Sachs disease Explanation: Tay-Sachs disease is an autosomal recessive disorder of Mendelian or single-gene inheritance. Coronary artery disease is a multifactorial inheritance disorder. Down syndrome is a numeric disorder involving autosomes. Marfan syndrome follows Mendelian inheritance but is autosomal dominant.

The health care provider informs the client that she is at risk for developing an autosomal recessive disorder. For which disorder may the client be at risk?

Tay-Sachs disease Explanation: Tay-Sachs disease is the only one of these diseases that is an autosomal recessive disorder. All the others are autosomal dominant disorders.

The nurse explains to prospective parents that AA or aa in a Punnett square represent two alleles of a given pair that are the same, or:

homozygotes. Explanation: When two alleles of a given pair are the same as in AA or aa, they are considered homozygotes.

Is it true or false that prenatal screening can be used to rule out all possible fetal abnormalities?

False Explanation: Prenatal screening cannot be used to rule out all possible fetal abnormalities. It is limited to determining whether the fetus has (or possibly has) designated conditions indicated by late maternal age, family history, or well-defined risk factors.

A mother who has one mutant allele on the X chromosome and one normal allele asks the nurse what the percentage is of passing it on to a daughter to be a carrier. The best response would be:

50% Explanation: The common pattern of inheritance is one in which an unaffected mother carries one normal and one mutant allele on the X chromosome. This means that she has a 50% chance of transmitting the defective gene to her sons, and her daughters have a 50% chance of being carrier of the mutant gene.

A newborn has been diagnosed with phenylketonuria (PKU). The nurse teaches the mother about a special diet to restrict phenylalanine intake. When does this diet need to be initiated?

7 to 10 days of age Explanation: Dietary treatment of PKU must be started early in neonatal life to prevent brain damage. Infants with elevated phenylalanine levels should begin treatment by 7-10 days of age.

A pregnant client's α-fetoprotein (AFP) returns elevated. The couple ask the health care worker to explain what this means. Which is the best response? "This is normal. The problem is if it is low, that means your baby will be born with trisomy 18 and will be intellectually disabled." "Elevated AFP means your baby is at risk of having a neural tube defect like spina bifida (an opening in the spine)." "This means your baby has Down syndrome. We won't know how severe until after you give birth." "This means you need to decrease your protein intake to prevent renal problems in your baby."

"Elevated AFP means your baby is at risk of having a neural tube defect like spina bifida (an opening in the spine)." Explanation: Maternal and amniotic fluid levels of AFP are elevated in pregnancies where the fetus has a neural tube defect (i.e., anencephaly and open spina bifida) or certain other malformations such as an anterior abdominal wall defect in which the fetal integument is not intact. Screening of maternal blood samples usually is done between weeks 16 and 18 of gestation. Although neural tube defects have been associated with elevated levels of AFP, decreased levels have been associated with Down syndrome.

The nurse is evaluating teaching provided to a parent of a male newborn with a karyotype of 47, XXY. Which statement indicates more teaching is needed?

"My child will have normal fertility when he matures." Explanation: Males with an extra X chromosome have Klinefelter syndrome. Klinefelter syndrome is characterized by a tall stature, and most males have some degree of language impairment. Infertility is common in men with Klinefelter syndrome because of a decreased sperm count. Androgen therapy can be initiated if there is evidence of a testosterone deficit.

Both members of a couple are carriers of an autosomal recessive trait. What will the nurse teach the couple about the risk of their child being affected?

"There is a 25% chance the child will be affected with the disease trait." Explanation: Autosomal recessive disorders include almost all inborn errors of metabolism, with deficiencies of enzymes rather than abnormal protein structure. Age of onset tends to be early in life. There is a two-in-four chance of having a child who is a carrier, but only a 25% risk for having an affected child. Phenylketonuria (PKU) is a rare autosomal recessive metabolic disorder that affects approximately 1 in every 10,000 to 15,000 infants in the United States. Infants with the disorder are treated with a special diet that restricts phenylalanine intake. If untreated, the disorder results in intellectual disability, microcephaly, delayed speech, and other signs of impaired neurologic development. Tay-Sachs disease is inherited as an autosomal recessive. Infants with Tay-Sachs disease appear normal at birth but begin to manifest progressive weakness, muscle flaccidity, and decreased responsiveness at approximately 6 to 10 months of age. The occurrence risks in each pregnancy (with both parents being carriers) are one in four (25%) for an affected child and two in four (50%) for a carrier child.

The parents of a newborn are relieved that their baby was born healthy, with the exception of a cleft lip that will be surgically corrected in 10 to 12 weeks. Which statement by the nurse to the parent's best conveys the probable cause of the newborn's cleft lip? "Though you are both healthy, you likely both carry the gene for a cleft lip." "A cleft lip can sometimes result from taking prescription drugs, even when they are taken as prescribed." "Provided one of you had the gene for a cleft lip, your baby likely faced a 50/50 chance of having one." "Your newborn's cleft lip likely results from the interplay between environment and genes."

"Your newborn's cleft lip likely results from the interplay between environment and genes." Explanation: A cleft lip is considered to be a multifactorial disorder, in which both environment and genes contribute to the condition. It does not depend solely on Mendelian patterns of inheritance. A cleft lip is not known to result from teratogenic drugs.

A woman gave birth to a small infant with a malformed skull. The infant grows slowly and shows signs of substantial cognitive and intellectual deficits. The child also has facial abnormalities that become more striking as it develops. What might the nurse expect to find in the mother's pregnancy history?

Chronic alcohol use Explanation: The infant's signs and symptoms are characteristic of fetal alcohol syndrome. Folic acid deficiency is associated with neural tube defects, such as anencephaly and spina bifida. Cocaine use is associated with some of the same signs and symptoms as alcohol use but does not produce the characteristic facial abnormalities of fetal alcohol syndrome. Herpes simplex infection, although it is associated with microcephaly, hydrocephalus, defects of the eye, and hearing problems, also does not produce characteristic facial abnormalities.

The nurse teaches a client about the medication classification system used to identify risk for teratogenicity. In which order will the nurse teach the client the categories are placed, from least risk to greatest for teratogenicity? Click an option, hold and drag it to the desired position, or click an option to highlight it and move it up or down in the order using the arrows to the left.

Class A Class B Class C Class D Class X Explanation: In 1983 the U.S. Food and Drug Administration established a system for classifying drugs according to probable risks to the fetus. According to this system, drugs are put into five categories: A, B, C, D, and X. Drugs in category A are the least dangerous, and categories B, C, and D are increasingly more dangerous. Those in category X are contraindicated during pregnancy because of proven teratogenicity.

A pregnant woman's ultrasound reveals intrauterine growth retardation (IUGR) and a TORCH agent is thought to be the cause. Which nursing action is appropriate?

Determine whether the client has been immunized against rubella. Explanation: TORCH stands for toxoplasmosis, other, rubella (i.e., German measles), cytomegalovirus, and herpes. Hepatitis, tetanus, and cholera are not included among lists of TORCH agents.

Maternal serum alpha-fetoprotein (AFP) is a screening test for which condition?

Down syndrome Explanation: There are several prenatal screening tests that can be done to determine the risk of having a child with Down syndrome. The most commonly used are blood tests that measure maternal serum levels of alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), unconjugated estriol, inhibin A and pregnancy-associated plasma protein A (PAPP-A). AFP is not a screening test for the other conditions.

Following routine newborn testing, an infant has been diagnosed with an elevated phenylalanine level. The nurse teaches the parents to follow a strict low-protein diet to prevent which major complication for the infant?

Impaired brain development Explanation: Infants and children with classic and mild PKU require dietary protein restrictions to prevent intellectual disability, microcephaly, and other signs of impaired neurologic development. Affected infants are normal at birth but within a few weeks begin to develop a rising phenylalanine level and signs of impaired brain development. Seizures, other neurologic abnormalities, decreased pigmentation of the hair and skin, and eczema often accompany the intellectual disability in untreated infants.

Which characteristic of genetic disorders involves a single-gene trait?

Mendelian patterns of inheritance Explanation: Single-gene disorders are characterized by patterns of transmission that follow the Mendelian patterns of inheritance. Multifactorial inheritance involves more than one gene mutation, rearrangement of groups of genes, and uneven numbers of some chromosomes in each cell.

A couple is scheduled to obtain familial lineage studies. The nurse is providing education. To which aspect of the DNA analysis should the woman pay particular attention regarding inherited disorders?

Mitochondrial DNA Explanation: Mitochondrial DNA is inherited maternally (i.e., from the mother) and provides a basis for familial lineage studies. Extrachromosomal DNA is used in the synthesis of mitochondrial RNAs and proteins used in oxidative metabolism. G-protein-linked receptors mediate cellular responses for numerous types of first messengers, including proteins, small peptides, amino acids, and fatty acid derivatives such as the prostaglandins.

A nurse confers with the attending physician about a client with encephalopathy who has been attributed to mitochondrial gene mutation. Why do mutations of the mitochondria affect the brain?

Mitochondrial mutations affect the ability of tissues to synthesize ATP, and tissues with high demands malfunction without enough ATP. Explanation: Tissues that have a high demand for the energy provided by ATP malfunction very quickly when ATP cannot be produced fast enough. This includes the brain, the muscular system, the auditory system, and the retina. Mitochondria cannot be silenced by the cell. Mitochondrial proteins and mutations can affect the cell where they reside but not the entire organ.

A 16-year-old male presents to the clinic complaining of headaches, trouble hearing the teacher in the front of the classroom, and ringing in the ears. He also revealed that every time he goes swimming underwater, he gets disorientated (which never happened when he was younger). Given these manifestations, the health care provider is going to start testing for:

Neurofibromas Explanation: NF-2, which is characterized by tumors of the acoustic nerve and multiple meningiomas, is much less common than NF-1. The disorder is often asymptomatic through the first 15 years of life. The most frequent symptoms are headaches, hearing loss, and tinnitus. Infants with Tay-Sachs disease appear normal at birth but begin to manifest progressive weakness, muscle flaccidity, and decreased attentiveness at approximately 6 to 10 months of age. Fragile X syndrome, an abnormality in the X chromosome, is the common cause of inherited intellectual disability.

An adolescent presents at the clinic with reports of pedunculated lesions projecting from the skin on the trunk area. The nurse knows that this is a sign of:

Neurofibromatosis type 1 Explanation: In more than 90% of persons with neurofibromatosis type 1, cutaneous and subcutaneous neurofibromas develop in late childhood or adolescence. The cutaneous neurofibromas, which vary in number from a few to many hundreds, manifest as soft, pedunculated lesions that project from the skin. Marfan syndrome affects several organ systems, including the ocular system (eyes), the cardiovascular system (heart and blood vessels), and the skeletal system (bones and joints). Down syndrome is a congenital condition characterized by varying degrees of intellectual disability and multiple defects. Klinefelter syndrome is a condition that occurs in men who have an extra X chromosome in most of their cells. The syndrome can affect different stages of physical, language, and social development. The most common symptom is infertility.

A nurse caring for a client with a genetic disorder of mitochondrial DNA assesses for abnormalities in which body system?

Neuromuscular Explanation: Mitochondrial DNA disorders, although rare, affect the tissues of the neuromuscular system.

Which condition is characterized by a deficiency of the liver enzyme phenylalanine hydroxylase?

Phenylketonuria Explanation: Phenylketonuria (PKU) is a rare metabolic disorder that affects approximately 1 in every 15,000 infants in the United States. The disorder, which is inherited as a recessive trait, is caused by a deficiency of the liver enzyme phenylalanine hydroxylase. As a result of this deficiency, toxic levels of the amino acid phenylalanine accumulate in the blood and other tissues. Tay-Sachs disease is a variant of a class of lysosomal storage diseases, known as the gangliosidoses, in which there is failure of lysosomes to break down the GM2 ganglioside of cell membranes. Cystic fibrosis is the production of abnormally thick mucus, leading to the blockage of respiratory and glandular ducts. Cri du chat is a syndrome involving chromosome 5.

Which microorganism can cross the placenta and enter the fetal circulation causing the most frequent fetal anomalies?

Rubella Explanation: TORCH stands for toxoplasmosis, other, rubella (German measles), cytomegalovirus, and herpes. This acronym can be used to remember the agents most frequently implicated in fetal anomalies. Strep throat, common colds, and the flu can cause concern for the mother but rarely result in fetal anomalies.

Select the screening procedure performed on newborns to decrease the risk of intellectual disability and compromised neurological development. Serum glucose test Erythromycin eye ointment application Vitamin K injection Serum phenylalanine test

Serum phenylalanine test Explanation: Newborn infants are routinely screened within 12 hours of birth for abnormal levels of serum phenylalanine to detect high levels that could cause irreversible intellectual disability. The other procedures that may be performed after birth would not be used as a screening tool for intellectual disability.

To prevent the pathophysiologic effects of spina bifida, which teachings will the nurse provide to the expectant mother?

Supplement your diet with at least 0.4 mg of folic acid daily Explanation: The major morphogenic defects of the spinal cord and brain are due to the abnormal formation or closure of the neural tube and surrounding tissues, problems that often result in spina bifida. Studies show when folic acid is taken by women of reproductive age, there is a significant decrease in neural tub defects like spina bifida. The recommended daily about is 400 μg (0.4 mg) of folic acid daily.

When the mother of an adolescent with Turner syndrome asks the nurse why the physician is prescribing estrogen therapy, the nurse provides which explanation?

To promote secondary sex characteristics Explanation: Estrogen therapy is initiated in adolescents to girls with Turner syndrome to promote the development of secondary sex characteristics.

The provider is doing genetic counseling with a client. He explains that which condition affects only females?

Turner syndrome Explanation: Turner syndrome describes an absence of all (45, X/0) or part of the X chromosome and, as such, is seen only in females. Klinefelter syndrome is a condition of testicular dysgenesis accompanied by the presence of one or more extra X chromosomes in excess of the normal XY complement. Most males with Klinefelter syndrome have one extra X chromosome (47, XXY). Down syndrome, trisomy 21, can be seen in either sex. Fragile X syndrome, as with other X-linked disorders, affects boys more often than girls.

The provider receives fetal karyotype results on one of his clients. The karyotype describes an absence of all or part of the X chromosome. Which condition does the fetus exhibit?

Turner syndrome Explanation: Turner syndrome is caused by an absence of all or part of the X chromosome. Down syndrome is a trisomy 21. Klinefelter syndrome is a condition of testicular dysgenesis accompanied by the presence of one or more extra X chromosomes in excess of the normal XY complement. Achondroplasia is a single-gene inheritance disorder.

In one family, a son was born with polydactyly toes while his sister had polydactyly fingers. In explaining this phenomenon in genetic terms to the parents, which concept should be addressed?

Variable expressivity of a gene Explanation: Autosomal dominant disorders are characterized by variable gene penetrance (degree to which the trait is displayed) and expression (differences in how the trait is displayed). Aneuploidy is not a single-gene disorder and does not follow the Mendelian pattern of inheritance. Deficiencies of enzyme synthesis are common in autosomal recessive disorders.X-linked inheritance can be dominant or recessive, but it is not autosomal.

While examining a client, the practitioner notices large, flat, cutaneous pigmentations. They are a uniform light brown with sharply demarcated edges. He uses a Wood lamp to better detect the lighter spots. The practitioner knows that the pigmentations may be a component of which disorder?

Von Recklinghausen disease Explanation: A second major component of type 1 neurofibromatosis, or von Recklinghausen disease, is the presence of large, flat cutaneous pigmentations known as café au lait spots. A Wood lamp, which uses ultraviolet light, can be used to detect lighter spots. The other options are chromosomal disorders and do not exhibit these pigmentations.

The nurse is explaining congenital defects to a newly pregnant client. She explains that one of the most common birth defects is:

cleft lip with or without cleft palate. Explanation: Cleft lip with or without cleft palate is one of the most common birth defects. Other congenital defects that are thought to arise through multifactorial inheritance are clubfoot, congenital dislocation of the hip, congenital heart disease, pyloric stenosis, and urinary tract malformation.

Unlike other teratogens, alcohol exposure during pregnancy (fetal alcohol spectrum disorders) can have what harmful effect on the fetus?

developmental abnormalities throughout the prenatal and postnatal period Explanation: Unlike other teratogenic exposures that cause abnormalities during a short period of time during fetal development (usually in the early weeks), fetal alcohol spectrum disorders (FASD) damage the chromosomes of the developing fetus as long as alcohol continues to circulate through the fetal bloodstream. FASD is diagnosed by the presence of three findings that do not include liver abnormalities and are not life threatening. Facial features characteristic of FASD are most noticeable during childhood. The facial features of FASD may not be as apparent in older people. Each defect can vary in severity, probably reflecting the timing of alcohol consumption in terms of the period of fetal development, amount of alcohol consumed, and hereditary and other environmental influences.

A young man has been diagnosed with Huntington disease following several months of progressive muscle weakness. The man has two young children: one boy and one girl. The nurse should teach the man that:

each child has 50% chance of developing Huntington disease. Explanation: In a single-gene autosomal dominant disease such as Huntington, the affected parent has a 50% chance of transmitting the disorder to each offspring. Sex-linked differences do not exist.

The most critical time for teratogenic influence in embryonic development is:

from day 15 to day 60 after conception. Explanation: The embryo's development is most easily disturbed during the period when differentiation and development of the organs are taking place. This time interval, which is often referred to as the period of organogenesis, extends from day 15 to day 60 after conception.

Which health care provider is the highest priority for immediate assistance in the first 24 hours following the birth of a newborn with a cleft lip?

lactation consultant Explanation: Newborns with a cleft lip typically have difficulty with feeding, and the assistance of a lactation consultant may be of help in establishing feeding patterns. Oxygenation is not a typical problem, while activities of daily living and assistive devices are not relevant considerations. Although social work is often of assistance when a child is born with a congenital condition, a cleft lip has fewer implications than most other inherited disorders.

The nurse is studying genetic disorders. She learns that an allele is:

one of two members of a gene pair, for a particular trait, in a chromosome pair. Explanation: The two members of a gene pair, one inherited from the mother and the other from the father, are called alleles. The presence of more than two chromosomes to a set is called polysomy. The physical trait associated with a particular gene is the phenotype.

Teratogenic substances cause abnormalities during embryonic and fetal development. These substances have been divided into three classes. These classes are called:

radiation; drugs and chemical substances; and infectious agents. Explanation: Teratogenic agents have been divided into three groups: radiation; drugs and chemical substances; and infectious agents. The period of organogenesis, the third trimester, and the second trimester are not teratogenic substances. They are time periods during the pregnancy. Teratogenic substances are not classified as outside, inside, or internal. Although drugs and chemical substances are a class of teratogenic agents, smoking is included in that class as a teratogenic agent. It is not a class unto itself. Bacteria and viruses are considered infectious agents and are therefore teratogenic agents.

The nurse teaches the client that ultrasonography will be used during prenatal testing to identify what type of abnormalities?

skeletal anomalies Explanation: Ultrasonography is the primary method for assessing fetal size and it screens for structural abnormalities that include the heart, skeleton, face, diaphragm, and gastrointestinal tract. Cytogenic studies and chromosomal analysis require amniocentesis, chorionic villus sampling, or umbilical cord blood. Alpha-fetoprotein (AFP) requires a maternal blood sample that is analyzed for serum markers associated with neural tube defects.