Biology

Human Genetics and Disorders

882 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

Which of the following defines a sequence in dysmorphology?

  1. Multiple anomalies attributed to mutation in a specific gene.

  2. Non-random happening of multiple anomalies is more frequent than expected by chance.

  3. Set of anomalies that can be attributed to consequences of a single aberrant developmental event.

  4. Set of anomalies resulting from damage to a fetal structure.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A sequence is a set of anomalies that result as a consequence of a single primary malformation.

Multiple choice

A major limitation of DNA-based carrier screening in cystic fibrosis is

  1. germline mosaicism

  2. laboratory errors in mutation analysis

  3. negative carrier testing

  4. incomplete ascertainment of mutations
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The current approach to carrier detection involves testing of a limited panel of mutations, which results in failure to detect some of the rarer CFTR mutations.

Multiple choice

The most significant limitation of molecular analysis of the HFE gene for screening for hemochromatosis in individuals of northern European descent is

  1. non-penetrance

  2. allelic heterogeneity

  3. genetic heterogeneity

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

A significant proportion of individuals who are homozygous for HFE mutation will not develop signs or symptoms of iron overload. There are only two HFE mutations that account for most affected individuals, and HFE mutation accounts for the majority of cases of hemochromatosis in individuals of northern European descent.

Multiple choice

A couple has a daughter suffering with Tay Sachs disease, and 4 normal children. Neither parent nor any of the four biological grandparents of the affected daughter had this disease. The most likely genetic condition leading to Tay Sachs disease is

  1. sex-linked recessive

  2. autosomal recessive

  3. autosomal dominant

  4. sex-linked dominant
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It must be recessive because both parents are normal, but one or both parents must have passed the disease allele to their daughter. Since one or both parents are heterozygous and are not affected by the Tay-Sachs allele, the disease must be recessive.

Multiple choice

In Maharashtra, in a small nuclear family, red nose proved to be an inherited trait due to a single genetic locus. The man's mother and one sister also had red nose but his father, his brother and two other sisters had normal nose. The man and his normal-nosed wife had seven children, including four boys and three girls. Two girls and two boys had red nose. The red nose trait is most probably

  1. autosomal dominant

  2. autosomal recessive

  3. sex-linked dominant

  4. sex-linked recessive
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since this genetic trait has been passed from generation to generation from both fathers to daughters and mothers to daughters, therefore it is typically autosomal dominant trait.

Multiple choice

Which of the following explains a particular type of polymorphism taking place within the gene that causes Huntington's disease in humans?

  1. Sequence-tagged sites (STSs)

  2. Short tandem repeat polymorphisms (STRPs)

  3. Expressed sequence tag (EST)

  4. Restriction fragment length polymorphism (RFLP)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The autosomal dominant gene leading to Huntington's disease has a mutation due to the extension of a triplet sequence of (CAG) within the coding region of the gene. Since the arrangement of the entire gene is now known, primers on either side of the tandem repeat arrangement of (CAG)n can be used to modify the region using the polymerase chain reaction and determine the size, i.e. number of times CAG is repeated. The triplet repeat arrangement is known as a STRPs, or short tandem repeat polymorphisms.

Multiple choice

Which of the following syndromes arises due to mutation in the TP53 tumor suppressor gene?

  1. Cowden syndrome

  2. Li-Fraumeni syndrome

  3. Hereditary breast and ovarian cancer

  4. Hereditary non-polyposis colon cancer (HNPCC)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is an autosomal dominant disease. It arises due to the mutation in the TP53 tumor suppressor gene. Its symptom includes cancers involving multiple sites including soft tissue sarcoma, osteosarcoma, etc.

Multiple choice

Which among the following is a X-linked dominant disorder?

  1. Incontinentia pigmenti

  2. Ectodermal dysplasia

  3. Albinism

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

It is a X-linked dominant disease. It results from the loss of function mutation of IKBKG gene. Primarily affects females and is lethal to hemizygous males in utero.

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.