Question

How many of the following genetic disorder is/are not related to non disjunction?

• A. Edward syndrome
• B. Down syndrome
• C. Pataus syndrome
• D. Car cry syndore

Answer 1

The correct option is D Car cry syndore

Non disjunction is the failure of the paired chromosomes to separate during the cell division, so that both the chromosomes goes only to one daughter cell and none of the chromosomes go to the other. Nondisjunction causes errors in chromosome number.

Trisomy 18 or Edward syndrome is caused by a meiotic nondisjunction event where a gamete is produced with an extra copy of chromosome 18 leading to 24 chromosomes in an individual.

Trisomy 21 or down syndrome is caused due to an error called nondisjunction in the cell division. It results in an embryo with three copies of chromosome 21 instead of having two.

Patau syndrome is caused by a chromosomal abnormality in the chromosome 13 due to nondisjunction of chromosomes during meiosis. It causes a full extra copy of chromosome 13 in the cell or a partial chromosome copy.

Cat cry syndrome is a rare genetic disorder which is caused due to the deletion of chromosome 5. It is not caused due to the nondisjunction of the chromosomes.