Ch. 1 Genetic & Congenital Alt.

Question 0

Marfan Syndrome: define & symptoms

Answer 0

Autosomial dominant disorder; rare, degenerative , generalized disorder of the CT; mutation on chromosome 15 that leads to elastin & collagen defects.

SYMPTOMS:
Increased height, long extremities, arachnodactyly, sternum defects, chest asymmetry, scoliosis, kyphosis, nearsighted, lens displacement, valvular defects, coarctation of the aorta

COMPLICATIONS:
Weak joints/ligaments, cataracts, retinal detachment, severe mitral regurgitation, spontaneous pneumothorax, inguinal hernia

Question 1

Autosomal dominant disorders

Answer 1

Single-gene mutations that are passed from an affected parent to an offspring regardless of sex

Question 2

Neurofibromatosis: define & symptoms

Answer 2

Autosomial dominant disorder; condition that involves neurogenic tumors that arise from Schwann cells

TYPE 1: involves cutaneous lesions such as raised bumps, “cafe au lait” spots, freckling–> mutation on chromosome 17

TYPE 2: bilateral acoustic tumors that cause heating loss–> mutation on chromosome 22

Question 3

Autosomal recessive disorders

Answer 3

Single gene mutations that are passed from an effective parent to an offspring regardless of sex, but occur only in homozygous allele pairs.

Question 4

Phenylketonuria (PKU): define & symptoms

Answer 4

A deficiency of phenylalanine hydroxylase (enzyme necessary for the conversion of Phenylaline to tyrosine
–>mutation on chromosome 12

Question 5

Tay-Sachs Disease

Answer 5

Deficiency/ absence of hexosaminidase A (which is necessary to metabolize certain lipids, these lipids accumulate and progressively destroy and demyelinate nerve cells).

SYMPTOMS:
Often causes death by five years of age, leads to a progressive mental and motor deterioration, affects almost exclusively individuals of Jewish descent;
Exaggerated startle reflex @ birth, apathy to loud sounds by age 3 to 6 months, inability to sit lift head or grasp objects, progressive vision loss, deafness and blindness, seizures, paralysis, spasticity, pneumonia

Question 6

Sex-Linked Disorders

Answer 6

Mutated genes on the X chromosome

Question 7

Fragile X Syndrome

Answer 7

X-linked, dominant disorder in which a single trinucleotide gene sequence on the X chromosome leads to failure to express a protein necessary for neural tube development.
CLINICAL MANIFESTATIONS:
Mental retardation, behavioral and learning disabilities, prominent jaw/ forehead, long narrow face with long or large ears, CT abnormalities, large testes, hyperactivity, seizures, speech difficulties, language delays, autistic-like behaviors