The chromosomal disorders are caused due to absence, excess or abnormal arrangement of one or more chromosomes. Failure of segregation of chromatids during cell division results in the gain or loss of chromosome(s), called aneuploidy.

Which of the following statements are correct with respect to the humans suffering from the disorder?

(A) One in every 800 live births shows this karyotype
(B) The affected individual has 45 chromosomes.
(C) Non-disjunction of chromosomes at the time of gamete formation causes this disorder.
(D) In this disorder, individual has 45 autosomes

Choose the correct answer from the options given below:

(A), (C) and (D) Only

The correct answer is Option (3) → (A), (C) and (D) Only

Statement (A): "One in every 800 live births shows this karyotype" — This statement is correct. The incidence of Down's syndrome is approximately 1 in every 800 to 1,000 live births.

Statement (B): "The affected individual has 45 chromosomes." — This statement is incorrect. Individuals with Down's syndrome have 47 chromosomes, not 45. They have an extra copy of chromosome 21.

Statement (C): "Non-disjunction of chromosomes at the time of gamete formation causes this disorder." — This statement is correct. The primary cause of Down's syndrome is nondisjunction, an error in cell division that leads to an extra chromosome 21.

Statement (D): "In this disorder, individual has 45 autosomes." — This statement is correct. In Down's syndrome, due to the presence of an extra copy of chromosome 21, there are 45 autosomes (44 + 1 extra chromosome 21), and 1 pair of sex chromosomes, which results in a total of 47 chromosomes.

Therefore, the correct answer is (A), (C) and (D) only.