Biology

Human Genetics and Disorders

844 Questions

Human Genetics and Disorders covers the inheritance patterns, genetic mutations, and molecular basis of hereditary diseases. Topics include sex-linked traits, cancer genetics, and metabolic disorders. This section tests knowledge critical for biology exams and general science papers.

Genetic mutationsInherited disordersCancer geneticsGenetic testingMendelian inheritance

Human Genetics and Disorders Questions

Multiple choice

The mutation in SERPINA1 gene causes

  1. hemochromatosis

  2. Wilson disease

  3. Cystic fibrosis

  4. α1-antitrypsin deficiency
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It is an autosomal recessive disease. It results from the mutation in SERPINA1 gene, which encodes α1-antitrypsin, a protease inhibitor. Lack of α1-antitrypsin in the lung leads to pulmonary damage due to inflammation.

Multiple choice

The autosomal dominant disorder resulting from the mutation in NF1 gene on chromosome 17 is

  1. neurofibromatosis

  2. tuberous sclerosis complex

  3. multiple endocrine neoplasia

  4. retinoblastoma
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is an autosomal dominant disease. It results from the mutation in NF1 gene on chromosome 17. It is associated with development of tumors of the nerve sheath. Other features of NF1 include café-au-lait spots, optic glioma, learning disability, and increased risk of malignancy or vascular disease.

Multiple choice

In which of the following phenotypic females does a pair of testis originate?

  1. 46, XY with X-linked androgen receptor inadequacy

  2. 45, X

  3. 46, XY with a point mutation in the HMG arena of the SRY gene.

  4. 46, XY with an interstitial deletion of Yp including the SRY gene.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The presence of a Y-chromosome predicts that testes will develop. Differentiation of external genitalia is controlled by the androgen derivative (5-alpha-dihydrotestosterone) and a defect in the androgen receptor which results in androgen insensitivity means that external male genitalia will not be stimulated to differentiate. Thus, this individual will look phenotypically female but will have undescended testes.

Multiple choice

A 30-year-old lady whose father is a suffer of Huntington disease requests genetic testing to determine if he has inherited the mutation. He is so far asymptomatic. She should be counseled

  1. At 30 years of age, she would already have shown symptoms if she had inherited the mutation.

  2. She faces a 50-50 risk of developing symptoms of Huntington disease.

  3. She remains at risk at age 30, though his risk is less than 50% being asymptomatic at this age.

  4. The fact that her father was the affected individual, which indicates that he must not have inherited the gene, since paternally-transmitted Huntington disease has onset in childhood.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Huntington disease displays age-dependent penetrance. Her risk is now less than 50%, though it is still possible that she will develop the disorder. 

Multiple choice

Among the following human diseases which is feeblest caused by aneuploidy?

  1. Turner syndrome

  2. Fragile X syndrome

  3. Down syndrome

  4. Klinefelter syndrome

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Fragile X syndrome is characterized by expansion of a CGG triplet repeat in the first exon of the FMR-1 gene on the long arm of the X chromosome, with the total chromosome number not being affected i.e. still euploid.

Multiple choice

Prader-Willi syndrome (PWS) can result from either an interstitial deletion involving the paternal copy of chromosome subregion 15q1-q13 or from maternal uniparental disomy of chromosome 15. The reason for this is

  1. the maternal copy of the gene(s) credited for PWS applies a dominant negative effect of the paternal allele

  2. PWS is a consequence of an anomaly of X-chromosome inactivation

  3. the paternal copy of the gene(s) responsible for PWS is imprinted and is not signified

  4. the maternal copy of the gene(s) responsible for PWS is imprinted and is not signified
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Prader-Willi Syndrome (PWS) is caused by genomic imprinting, defined as the differential expression of maternal and paternal alleles. When the information in region 15q11-q13 is derived only from a mother (either via uniparental disomy (both chromosomes from a single parent) or deletion on the paternal chromosome), the maternally imprinted chromosome is unable to express its genetic information and the result is PWS.

Multiple choice

Which of the following face the considerable danger for Rh +ve mother and her developing embryo incompatibility problems like erythroblastosis fetalis?

  1. Europeans

  2. Africans

  3. Native Americans

  4. All the peoples of the world are at equal risk
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Europeans have the highest frequency of Rh negative people (40%), which puts them at the highest risk for this problem. About 13% of newborn Europeans are at risk, but we can now prevent the life threatening complications in most cases.

Multiple choice

Deletions of HBA1 and HBA2 genes pretend to govern most cases of

  1. sickle cell anemia

  2. hemophilia A

  3. thalassemia

  4. porphyria

  5. chronic myeloid leukemia
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Thalassemia is an inherited disease of faulty synthesis of hemoglobin. It is a barely detectable abnormality of blood, to severe or fatal anemia deletions of HBA1 and  HBA2 genes pretend to  govern  most cases of the thalassemia.

Multiple choice

Mutation in the RET oncogene is associated with increased risk of

  1. PNET cancers

  2. Endometrial cancer

  3. Prostate cancer

  4. Adenocarcinoma

  5. Medullary thyroid cancer
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Adenocarcinoma is a cancer arising from the mucosa of the rectum. Cancer cells can also spread from the rectum to the lymph nodes on their way to other parts of the body. RET mutation is responsible for adenocarcinoma RET mutation is responsible for increased risk of medullary thyroid cancer, as well as multiple endocrine neoplasia 2, in which pheochromocytoma and parathyroid adenoma also occur.