Deck 13: Molecular Detection of Inherited Diseases

Question 1

Missense mutations in cell growth regulator proteins can result in which of the following diseases?

A) Familial hypercholesteremia
B) Muscular dystrophy
C) Neurofibromatosis
D) Phenylketonuria

Answer 1

Neurofibromatosis

Question 2

What defines a congenital disease?

A) Always heritable
B) Present at birth
C) Limited to blood disorders
D) Symptoms delayed until puberty

Answer 2

Present at birth

Question 3

In a pedigree, an affected female will be indicated by which of the following symbols?

A) Open circle
B) Shaded circle
C) Open square
D) Shaded square

Answer 3

Shaded circle

Question 4

Li-Fraumeni syndrome, in which affected patients have an increased predisposition to cancer, is caused by a mutation in which of the following genes?

A) Hemoglobin beta
B) Dystrophin
C) Phenylalanine hydroxylase
D) p53 tumor suppressor gene

Question 5

A patient is tested to determine the number of CGG repeats in the FMR1 gene by Southern blot. The patient is found to have a band that runs above the normal control band. Which of the following is the correct interpretation of these results?

A) The patient is normal.
B) The patient has Huntington's disease.
C) The patient has Tay-Sachs disease.
D) The patient has full fragile X mutation.

Question 6

Which of the following syndromes is caused by deletions in mitochondrial genes as detected by Southern blot?

A) Pearson's
B) NARP
C) Leber's
D) Mitochondrial DNA depletion

Question 7

One of the rarest genome mutations, in which the affected infant has a cleft palate, abnormal heart, and developmental delays and usually does not survive beyond 6 months because of trisomy 13, is which of the following syndromes?

A) Down's
B) Turner's
C) Patau's
D) Edward's

Question 8

Mitochondrial mutations primarily affect which of the following tissues?

A) Skin
B) Bone
C) Muscle
D) Lung

Question 9

How are transmission patterns determined?

A) Family history
B) Karyotyping
C) Environmental studies
D) Comparing unrelated individuals

Question 10

All members of a family carry the same gene polymorphism associated with a certain phenotype. There is a range of phenotypes among the family members. What is the term for this observation?

A) Variable expressivity
B) Complete penetrance
C) X-linked
D) Y-linked

Question 11

A patient with abnormally high iron levels is tested to determine if hemochromatosis, specifically the C282Y mutation in the HFE gene, is the cause. The patient's DNA is isolated from whole blood and amplified. Amplicons are then cut with RsaI, and the resulting fragments are separated by gel electrophoresis. There are no RsaI sites in the normal 250 bp PCR product, while the C282Y mutation generates one RsaI site. The lane containing the patient's sample has three bands at 250 bp, 140 bp, and 110 bp. Controls were acceptable. Which of the following is the correct interpretation of these results?

A) Normal
B) Heterozygous mutation
C) Homozygous mutation
D) Wrong target and method performed for this disease

Question 12

Which of the following is a genetic storage disease in which sulfatides accumulate inside the lysosomes?

A) Tay-Sachs
B) Niemann-Pick
C) Gaucher's
D) Pseudo-Hurler polydystrophy

Question 13

A deceased family member is indicated in a pedigree by which of the following?

A) Triangle
B) Shaded symbol
C) Slash through the symbol
D) X across the symbol

Question 14

Genetic analysis of four generations of a family reveals that about 50% of the males in the family are affected by a mutation and about 50% of the females are unaffected carriers of the mutation that affects the males. What type of inheritance pattern is seen in this family?

A) Autosomal-dominant
B) Autosomal-recessive
C) X-linked recessive
D) Y-linked recessive

Question 15

Seventeen members of an extended family have a gene mutation. Only two of them have the associated phenotype. What is the term for this observation?

A) Complete penetrance
B) Mosaicism
C) Autosomal dominant inheritance
D) Incomplete penetrance

Question 16

Almost all sex-linked disorders involve which of the following chromosomes?

A) X
B) Y
C) 1
D) 22

Question 17

A patient presented complaining of slurred speech and difficulty swallowing. The patient's DNA was tested to determine the number of CAG repeats in the Huntington gene by PCR. The patient had 10-29 repeats. This result is interpreted as which of the following?

A) Normal
B) Abnormal expansion consistent with Huntington's disease seen
C) Patient is at risk of Huntington's disease
D) Inconsistent results that should be repeated

Question 18

Fertilization where one gamete contains an extra copy of one chromosome will result in what chromosomal abnormality?

A) Monosomy
B) Disomy
C) Trisomy
D) Tetraploidy

Question 19

A patient is tested for the presence of the factor V Leiden mutation by PCR-RFLP. The mutation forms a recognition site for the MnlI restriction enzyme. Isolated DNA is amplified by PCR, and the resulting amplicons are cut with MnlI and separated by gel electrophoresis. Two bands are seen in the lane loaded with the patient's sample, one at 153 bp and the other at 67 bp. One band (220 bp) is seen in the normal control. Which of the following is the correct interpretation of these results?

A) Normal
B) Heterozygous mutation
C) Homozygous mutation
D) Wrong target and method performed for this disease

Question 20

The mutation del(15)(q11q13) on the paternal chromosome results in a disease that is different from when the same mutation occurs on the maternal chromosome. This difference results from which of the following?

A) Multifactorial inheritance
B) Imprinting
C) Hormonal differences
D) Sex linkage

Question 21

What is indicated by the term CYP2A6?

A) Cytochrome P-450, subfamily IIA, polypeptide 6
B) Cytochrome P-450, subfamily IIA 6
C) Cytochrome P-450, subfamily 6, polypeptide 2A
D) Cytochrome P-450, polypeptide A6, subfamily II

Question 22

The detection of mitochondrial mutations is complicated by which of the following?

A) Methods available for analyzing mitochondrial genes
B) Small number of mitochondria in a cell
C) Lack of information about the mitochondrial genome
D) Presence of mutated and normal mitochondria in the same cell

Question 23

A (F508del) mutation in the CFTRgene is responsible for causing which of the following diseases?

A) Idiopathic congenital central hypoventilation syndrome
B) Friedreich's ataxia
C) Cystic fibrosis
D) Leber's hereditary optic neuropathy

Question 24

Mutation in this gene product that catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate can lead to cardiovascular disease and complications in pregnancy.

A) TP53
B) MTHFR
C) F5
D) HLA-H

Question 25

A pedigree was examined over four generations of a family with an abnormal rate of genetic disease. Scientists observed that males and females alike were affected by the disease but only when their mother was also affected. The children of affected males were all normal. All the children of affected females were affected. Which of the following describes this inheritance pattern?

A) Mitochondrial related
B) Autosomal dominant
C) Autosomal recessive
D) Sex linked