Genetic and Congenital Disorders

Question 1

what is a congenital disorder?

Answer 1

defect present at birth; it can be from genetic vs non genetic factors such as infections, drugs, etc
also called “birth defects”

Question 2

What is a genetic disorder?

Answer 2

a disorder which involves a permanent change in the genome; may be apparent at birth or later in life; example is CVD

Question 3

What do genetic disorders effect? What are most caused by?

Answer 3

Gene expression; alteration of DNA that affects the synthesis of a single gene product

Question 4

What are two types of problems that can lead to a genetic disorder? Give examples

Answer 4

Gene problem: single gene traits; multifactorial inheritance
Chromosome problem: nondisjunction (Downs syndrome), Rearrangement of genes (translocation), deletion or duplication of genes (most common type we pass down), or abnormal # of chromosomes

Question 5

What are single gene disorders caused by? Where are they found in DNA? What pattern of inheritance do they follow? What do these disorders lead to?

Answer 5

a single mutant or defective gene
autosomes or X chromosome
Mendelian pattern of inheritance
abnormal protein or decreased production of a product

Question 6

What is multifactorial inheritance?

Answer 6

Many factors (genetic and environmental) are involved when this birth defect presents; combo of genes from both parents plus the environment

Question 7

What are Mendel’s 3 laws of inheritance?

Answer 7

Laws of dominance
Law of segregation
Law of independent assortment

Question 8

What is Mendel’s law of dominance?

Answer 8

when there are alternate forms of a gene, the gene that will be expressed is the dominant form
TT x tt = 100% Tt

Question 9

What is Mendel’s law of segregation?

Answer 9

inherited traits are defined by gene pairs and sex cells contain only one gene of the pair
Tt x Tt = 75% Tall and 25% short

Question 10

What is Mendel’s law of independent assortment?

Answer 10

inheritance of one trait is not dependent on the inheritance of the other bc traits are arranged separately from each other (gene pods)

Question 11

What is a carrier?

Answer 11

a person who is heterozygous for a recessive trait and DOES NOT manifest the trait

Question 12

What are four basic inheritance patterns?

Answer 12

Autosomal dominant, autosomal recessive, X-linked, Mitochondrial inheritance

Question 13

What is autosomal dominant pattern? What is the mutation affecting? What % of parents pass this to their offspring?

Answer 13

a single mutant allele from an affected parent is transmitted to an offspring regardless of sex; its affecting structural proteins (fibrous/collagen) or regulatory proteins of rate limiting steps; affected parent has 50% chance of transmitting disorder to each offspring (ex Marfans)

Question 14

What is an autosomal recessive pattern of inheritance? What is % that offspring will have disorder? How about being a carrier?

Answer 14

manifested ONLY when both autosomes of the gene pair are affected; parents are carriers and doesn’t affect sex; 25% of offspring will have disease, 25% won’t, and 50% will be carrier; Mutations involving enzymes (ex: cystic fibrous, sickle cell); can happen with INCEST

Question 15

What is an X linked pattern of inheritance?

Answer 15

Mutations on the X chromosome; most often affect males since they only have one X (ex; hemophilia A)

Question 16

What is mitochondrial inheritance?

Answer 16

mutations in mitochondrial DNA or in nuclear DNA encoding mitochondrial proteins (passed down from mother)

Question 17

What does wide variation in gene penetrance and expression mean in terms of Autosomal dominant inheritance?

Answer 17

It means that there is variation in severity for every person with the disease (gene expressivity varies)

Question 18

What is Marfan’s syndrome? What type of inheritance pattern is this? What’s the gene affected? What is average age of death?

Answer 18

connective tissue disorder with changes in the skeleton, eyes and CV system (long thin body, extremities, fingers; Cardio- MVP, aortic valve probs, aneurysms); Autosomal dominant inheritance; gene that codes for fibrillin-1; age is 30-40 usually due to cardiac

Question 19

What is neurofibromatosis? what type of inheritance is this. What does it result from?

Answer 19

Autosomal dominant; condition involves neurogenic tumors that arise from schwaan cells; results from genetic defect in tumor-suppressor genes (regulate cell differentiation and growth); 50% are autosomal dominant and 50% are new mutation (grow back)

Question 20

What is phenylketonuria? What type of inheritance is it? How often does it occur? What are symptoms? What type of screening tool is associated with this disease? What is the treatment for it

Answer 20

deficiency of the liver enzyme that converts the AA phenylalanine to tyrosine; high levels of phenylalanine; autosomal recessive; 1 in every 15,000 infants
symptoms: strong musty odor in infants, retardation, impaired neurologic development, microcephaly; Newborns are screened at birth to prevent irreversible mental retardation; tx is special diet restricting phenylalanine (low protein)

Question 21

What is Tay-Sachs disease? What is its pattern of inheritance? What population is it present in? What are symptoms? Is there a cure?

Answer 21

Disease where there is no lysosomal degradation and additional protein deposit in the nervous system/neurons destroyed; autosomal recessive; prevalent in Eastern European jews; north at birth but then progressive weakness, decreased attentiveness by 6-10 months, seizures and blindness; death by age 4-5; no cure but can test for deficiency of enzyme (lysosomal hex a enzyme) which can identify carriers