Final Final Study - Jes

Question 1

6 yo old presents with multiple brown freckles on cheeks, nose and upper lip, forearms, and thighs. Physical exam and mental all normal. Past medical reveals severe photosensitivity at 6 mo. Most likely diagnosis?

Answer 1

Xeroderma pigmentosum

Question 2

Study of 600 families previously diagnosed with hereditary nonpolyposis colon cancer found 100 individuals with no evidence of mutation in the MLH1 gene as expected. Further analysis revealed 25 had mutations on both alleles of the gene encoding adenine glycosylase. Which of the following is most likely affected in these pts?

Answer 2

Base excision repair

-proteins are mismatched

Question 3

A newborn female is the 2nd child born to a 36 yo female and 47 yo male. The infant has round face, low hairline, hypertelorism, epicanthal folds…… There is no family history of a similar presentation. Which of the following procedures is recommended to establish a diagnosis?

Answer 3

Karyotype

Question 4

A karyotype of a 1 week old child revealed 49,XXXXX in all cells and the child was diagnosed with penta-X syndrome with multiple congenital anomalies. Which of the following is the most likely etiology of this disease?

Answer 4

Nondisjunction

Question 5

The laboratory performed analysis of blood chemistries and enzyme levels on an infant with penta-X syndrome. What is the theoretical expectation for these results compared to normal newborn levels?

Answer 5

Same

-X-activation inactivation

Question 6

Among gametes produced by an individual carrying a chromosome 14/21 translocation, fewer infants are actually born with translocation Down Syndrome than expected. Which of the following best explains this discrepancy between observed and expected finding?

Answer 6

In utero loss of fetuses with Down Syndrome

Question 7

The pedigree shows a large extended family that demonstrated mild symptoms similar to incontinentia pigmenti. Which of the following mechanisms of inheritance is demonstrated for this family

Answer 7

X-linked Dominant

• affected sons pass trait to all daughters, but no sons
• affected daughters pass trait to 50% of sons and daughters

Question 8

At a 6-mo well baby check, the mother mentions the infant’s diaper turn dark before washing. Normal mental/physical exam. Urine normal, homgentisic acid were positive. Best diagnosis?

Answer 8

Alkaptonuria

-urine darkens when exposed to air

Question 9

An 11 yo male diagnosed 5 yrs after having osteosarcoma removed. Mother died from breast cancer and 5 other family members had cancer. Which gene most likely candidate for the cancer in this family?

Answer 9

TP53

-has Li Fraumeni syndrome - multiple cancers due to mutation in p53

Question 10

Lab testing reveals H antigens on the surface of RBCs. Which blood type most likely?

Answer 10

Type O, Rh(D) positive

Question 11

2 day old infant admitted to neonatal intensive care unit with mild jaundice and mild edema. Parents have one other child and no significant medical history. Laboratory tests reveal anemia and a positive direct Coombs test. Which of the following best explains the diagnosis?

Answer 11

Rhd (negative) mother
RhD (positive) father
RhD (positive) baby
-Rh incompatibility aka erythroblastosis fetalis

Question 12

15 yo female evaluated for delayed puberty. Physical exam is normal female genitalia. Imaging studies reveal undeveloped streak gonads. Chromosomal studies reveal 46,XY karyotype. Which best explains this?

Answer 12

SRY mutation

Question 13

A study of the long QT syndrome in a Utah community demonstrated a founder affect with an incidence of 1 in 5000. What is freq of unaffected individuals in population?

Answer 13

0.998

Question 14

5 yo hospitalized with anemia, jaundice and cholelithiasis. Lab reveals hemolysis and sickle cell anemia, which occurs with freq of 1 in 500. Which of the following represents the freq of sickle cell carriers in population?

Answer 14

Ans = 0.086

-want 2pq

Question 15

A couple has 2 children with rare disorder and is concerned unborn child might develop. What is probability 3rd will get it?
Pedigree shows mother as having disease and father doesn’t

Answer 15

25%
-autosomal recessive presentation
I think this one is fucking wrong….but what do I know? ;)

Question 16

In a community, type O blood does not exist even though it is most common in most populations. What describes this force best?

Answer 16

Decreased immigration

Question 17

21 year old female has sickle cell. Recently wants kids, sought genetic counseling with normal husband. Genetic analysis revealed G to A DNA nucleotide change in her B-hemoglobin alleles. Her husband doesn’t have mutation. Best description of this mutation?

Answer 17

Transition

-single nucleotide change is a pt mutation

Question 18

A study of unrelated individuals diagnosed with xeroderma pigmentosum identified mutations in different genes common among the individuals presenting with the same clinical symptoms. Which term best describes?

Answer 18

Locus heterogeneity

Question 19

Karyotypic analysis is performed with leukocytes from a stillborn infant to identify possible chromosome disorder. All homologous pairs of chromosomes were present and no abnormality was found. Which describes these homologs best?

Answer 19

They carry the same genes but not necessarily the same alleles

Question 20

An infant has flat profile, upward slant to eyes, short neck, Brushfield spots on iris and deep crease on palm. Karyotypic analysis shows a translocation rather than a trisomy and unaffected mother carries same translocation. Most likely karyotype for mother?

Answer 20

46,XX/45,XX,t(14;21)

• Holy fuck
• pt presents with translocation Down syndrome. Mother is an unaffected carrier. Mother also is a mosaic carrier.

Question 21

Best lab marker for chronic myelogenous leukemia?

Answer 21

Philadelphia chromosome