Pathophysiology Chapter 21
How many autosomes do humans have?
22 pairs
How many pairs of chromosomes are in humans?
23 pairs, 46 total
What is Klinefelter syndrome?
47, XXY
what causes a translocation mutation?
A piece of one chromosome breaks off and attached to another chromosome
What is gene therapy?
A possible way to fix a genetic problem
What is genetic testing?
A test to diagnose a condition in an individual based on family history and symptoms
What are some autosomal-dominant disorders?
Adult polycystic kidney disease Huntington chorea Familial hypercholesterolemia Marfan syndrome
What is a teratogenic agent?
Agent that causes damage during fetal development
Name drug and chemical teratogens?
Alcohol Androgen hormones Coumadin anticoagulants lead tetracyclines mercury
What are some blood tests of pregnant women?
Alpha-fetoprotein HCG Unconjugated estriol
What screening procedure is used to confirm down syndrome?
Amniocentesis
What are the in-utero diagnostic tools for testing?
Amniocentesis and chorionic villi assay
What is Hemophilia A?
An X-linked recessive disorder that causes patients to bleed due to a defect in blood clotting
What is TORCH?
An acronym for maternal infections that can cause anomalies
Characteristic of X-linked recessive disorders
An allele carried on the X chromosome but not the Y
What is Phenylketonuria (PKU)?
An autosomal disorder that the amino acid phenylalanine is unconverted, causing neurological damage
What is Tay-Sachs disease?
An autosomal recessive disorder that is caused by a build-up of lipids in the brain that impede nervous function
What is Marfan syndrome?
An autosomal-dominant disorder that affects the body's connective tissues
What is adult polycystic kidney disease?
An autosomal-dominant disorder that causes cysts in your kidneys, and your kidney enlarges and loses function
What is Huntington chorea?
An autosomal-dominant disorder that causes the degeneration of nerve cells in the brain
what is cystic fibrosis?
An autosomal-recessive disorder of the cell membranes. Causes thick, sticky mucus to build up in air passages and pancreas.
What are some multifactorial disorders?
Anencephaly Cleft lip and palate clubfoot congenital heart disease Myelomeningocele schizophrenia
Inheritance of one allele causes these disorders
Autosomal dominant disorders
What inheritance patterns are single-gene disorders classified by?
Autosomal-recessive Autosomal-dominant X-linked recessive X-linked dominant
What is a multifactorial disorder?
Caused by a combination of environmental factors and mutations in multiple genes
A type of duplication mutation
Charcot-Marie-Tooth, part of chr 17 duplicated
What are some X-linked recessive disorders?
Color blindness Duchenne muscular dystrophy Hemophilia A
Name some physical agent teratogens
Hyperthermia high-dose ionizing radiation
A type of deletion mutation
Cri-du-chat
What are some autosomal-recessive disorders?
Cystic fibrosis Phenylketonuria sickle cell anemia tay-sachs disease
Name some teratogens that are infectious agents.
Cytomegalovirus Rubella Toxoplasma gondii Varicella
What are the 4 main type of structural chromosomal disorders
Deletion Duplication Inversion Translocation
How is chromosomal defect caused?
Error during meiosis deletion, duplication, inversion and translocation
What are some neonatal tests?
Excreted metabolites (PKU) Blood testing
Females and males are affected the same with fragile X syndrome.
False. Girls get it less often
What is an example of an X-linked dominant disorder?
Fragile X syndrome
All cells have the same genotype except for what cells?
Gametes or sex chromosomes
What is the ultimate goal for genetic engineering?
Insert normally functioning allele to prevent disease
What medications and vaccines are products of genetic engineering?
Insulin HGH Hep B vaccine
What is Genetic engineering?
Isolating, copying, transplanting genes
Classifications of chromosomal disorders
Numerical or structural
What is Turner syndrome?
Occurs in females when they only have one X chromosome. Monosomy X
What is genetic screening?
Offered to populations at an increased risk but have no symptoms
Monosomies
Only one side of the pair of the chromosome is present.
Who is testing recommended for?
Patients with a family history Previous birth to a child with an abnormality Certain ethnic groups Pregnant women >35
what is an incomplete dominant?
People who are heterozygous for an autosomal recessive disorder but show some clinical signs
What does down syndrome affect?
Physical and mental development
When can you do diagnostic testing?
Prior to conception During first trimester In a newborn
How may inherited disorders be caused?
Single-gene expression chromosomal defect multifactorial disorders
Characteristics of down syndrome
Small head, round face slanted eyes large tongue small hands short stature loose joints (hypotonic) Delayed developmental stages cognitive impairment delayed or incomplete sexual development
What does TORCH stand for?
T: *toxoplasmosis* O: *other parvo- b 19, varicella zoster* R: *rubella* C: *cytomegalovirus* H: *herpes*
Trisomies
The copies of the chromosome
What is single-gene expression?
Trait controlled by one set of alleles and given to subsequent generations
What is used to screen for down syndrome?
Triple or quad screening tests (ultrasound and blood tests?
Edwards syndrome
Trisomy 18
Women can have x linked recessive disorders
True. However they are usually just carriers
If a parent is homozygous for an autosomal recessive disorder, they are
affected
What is a delayed lethal genotype?
allele for disorder may have been passed on to next generation before diagnosis of disease in parent
What is sickle cell anemia?
an autosomal-recessive disorder that causes a problem making the hemoglobin of the red blood cells., A genetic disorder causing red blood cells to be rod/sickle shaped. This causes them to get stuck in capillaries and the bodies cells become deprived of oxygen
Term for heterozygous and unaffected
carrier
What chromosome is usually affected with an inversion mutation
chromosome 2, typically asymptomatic
Characteristics of fragile x syndrome
cognitive deficit learning disorders prominent lower jaw macroorchidism large ears
What is a congenital disorder?
disorder present at birth
Most common cause of mental retardation in the US
fragile x syndrome
What is a genotype?
genetic makeup of an organism
What is a karyotype used for?
identify chromosomal abnormalities
Risk of down syndrome increases with what?
maternal age
What is an autosome?
non-sex chromosome
define phenotype
physical appearance, the expression of your genes
Define karyotype
picture of all the chromosomes of an organism
Another way that congenital disorders may occur
premature birth or difficulties during labor and delivery
Characteristics of Turner syndrome
short stature, webbed neck, lack of ovarian development
What is myelomeningocele?
the most common and serious form of spina bifida in which the bones of the spine do not completely form, resulting in an incomplete spinal canal, causing the spinal cord and meninges to stick out of the childs back
Down syndrome is also known as
trisomy 21; 3 copies of chromosome 21
