Genetic Disorders

Question 1

What are the 3 chromosomal disorders?

Answer 1

Trisomy 21: Down Syndrome
Trisomy 18: Edwards Syndrome
Trisomy 13: Patau Syndrome

Question 2

What is non-disjunction?

Answer 2

During cell division and mitosis, two chromosomes go to one cell. They staged together and now the cells have an extra 21 chromosomes.

Question 3

What is translocation?

Answer 3

Early on after fertilization and the most common reason why we end up with a trisomy. The chromosome can break off and stick on another chromosome.

Question 4

What is mosaicism?

Answer 4

Happens later in cell division. Same error as non-disjunction, but it is occurring later. We see a less severe presentation.

Question 5

Is there an increased risk of Down Syndrome with maternal age?

Answer 5

Yes

Question 6

Clinical picture of Down Syndrome.

Answer 6

Small stature, upward slant of eyes, wide gap between toes 1 and 2, micrognathia, small oral cavity resulting in protruding tongue, speckling of iris, epicanthal fold at eyes, saddle nose, small ears, and short broad hands with palmar crease.

Question 7

Neuropathophysiology of Down Syndrome.

Answer 7

Simplicity in convolutional pattern, reduced synaptogenesis, lack/delay of myelination, decreased number of small neurons, structural abnormalities of neurons, and increased number of neurofibrillary tangles and senile plaques.

Question 8

What is microbrachycephaly, and what genetic disorder is it associated with?

Answer 8

Flattening of the skull from A-P, so it is wider M-L. This is associated with Down Syndrome.

Question 9

MSK picture of Down Syndrome.

Answer 9

Hypotonia, muscular variations, foot deformities, hip subluxation/dislocation, patellar instability, scoliosis, and A/A instability.

Question 10

Sensory deficits of Down Syndrome.

Answer 10

Hearing loss, strabismus, cataracts, chronic otitis media, nystagmus, and myopia.

Question 11

What are the 3 ways to diagnose Down Syndrome?

Answer 11

Karyotype pre/postnatal: amniocentesis
Alpha-fetoprotein
Observation at birth

Question 12

What does AFP stand for? What genetic disorder is it associated with and what does it mean?

Answer 12

Alpha-fetoprotein: blood test from the mother, typically during the second-trimester. They could identify the amount of AFP. In Down Syndrome, the levels of AFP are abnormally low.

Question 13

What is amniocentesis?

Answer 13

Large needle through the abdomen, through the uterus, and withdraw amniotic fluid surrounding the baby. The increased risk could cause the mother to go into labor. Analyzing the cells of the baby that would be floating in the fluid and seeing if the trisomy is present.

Question 14

Is Edwards Syndrome correlated with advanced maternal age?

Answer 14

Yes

Question 15

Clinical Picture of Edwards Syndrome.

Answer 15

LBW, small stature; CV/GI/urogenital/skeletal malformations; long/narrow skull, low set/misshapen ears, tone abnormalities, profound MR; neuropathy.

Question 16

What genetic disorder is associated with a long A-P and narrow M-L shaped head?

Answer 16

Edwards Syndrome

Question 17

Clinical Picture of Patau Syndrome.

Answer 17

CNS/CV/MS/urogenital malformations, severe/profound MR, anophthalmia/microphthalmia.

Question 18

What are sex chromosome disorders?

Answer 18

Turner syndrome, Klinefelter syndrome, and Fragile X syndrome.

Question 19

What is Turner Syndrome? Is it correlated to maternal age?

Answer 19

Extra or missing sex chromosome. There is NO correlation to maternal age.

Question 20

What are some physical features of Turner Syndrome?

Answer 20

Webbed neck, cubital valgus, dorsal edema of hands and feet, hypertelorism, epicanthal folds, ptosis, elongated ears, and growth retardation.

Question 21

What are some systemic features of Turner Syndrome?

Answer 21

Congenital heart disease, kidney malfunctions, hearing loss, decreased gustatory and olfactory, deficits in spatial perception and orientation, average intellect in most, and sexual infantilism.

Question 22

What are some skeletal abnormalities of Turner Syndrome?

Answer 22

Hip dislocation, foot deformities, osteoporosis, and idiopathic scoliosis.

Question 23

What is Klinefelter Syndrome? What is the clinical picture?

Answer 23

Two x chromosomes and one y, male. Testes fail to enlarge, gynecomastia, normal IQ, and sterility.

Question 24

What is Fragile X Syndrome? What are some clinical features?

Answer 24

Structural abnormality of X chromosome; large head/ears/jaw, myopic, v-shaped palate, large testes, and active/autistic.

Question 24

What is Fragile X Syndrome? What are some clinical features?

Answer 24

Structural abnormality of X chromosome; large head/ears/jaw, myopic, v-shaped palate, large testes, and active/autistic.