Question

Triple-X syndrome (XXX) resulting from Paternal (male) inheritance occurs due to

A Primary Non-disjunction

B Haploid gametes from both parents

C Secondary Non-disjunction

D Either A or C

E All of the Above

Answer 1

correct answer: A. Primary non disjunction

Explaination:XXX syndrome is also called as 47,XXX trisomy because an extra chromosome is present in the cell resulting in 47 chromosomes instead of 46. The individual is a female

it is result of non disjunction during gametes formation in either male or female parent.

one of the gamete from any one of the parent is normal with only one X chromosome. that is 23+X

while another gamete contains two X chromosomes . That is 23+XX

Primary non disjunction occurs in a normal diploid cell during meiosis

while secondary non disjunction occurs in the abnormal cell that already has one extra X chromosome, in females.

therefore here parental male inherits only through Primary non disjunction.