Question

Syndrome in which somatic cells contain three sex chromosomes XXY, is?
A) Turner’s syndrome.
B) Down’s syndrome.
C) Klinefelter’s syndrome.
D) Super female.

Answer 1

Hint: These are characterized by trisomy of sex chromosome. The individuals are sterile males having very low sperm count.

Complete answer:
> Trisomics (2n = 47) and monosomics (2n = 45) are well known aneuploids among human beings. They may involve a sex chromosome or an autosome. Turner’s syndrome, super female (triple X syndrome) and Klinefelter’s syndrome are the examples of aneuploidy involving sex chromosomes; however, Down’s syndrome is an example of autosomal aneuploidy.
> Turner's syndrome is characterized by monosomy of X-chromosome. It is represented as 44 +XO. The individuals with the syndrome are sterile females with webbed necks.
Down's syndrome is caused due to trisomy of an autosome i.e. chromosome 21. It is denoted as 45+XY or 45+XX. Patients with Down syndrome are short in physique. The individuals having this syndrome are less in mental ability but can be given training in routine mechanical skills. This syndrome does not affect the number of sex chromosomes in individuals.
> Klinefelter’s Syndrome is characterized by a trisomy of X-chromosome. It is marked by the presence of one extra X chromosome in the individual (44+XXY). The individuals having this syndrome are males as they possess one Y chromosome. The individuals are sterile with small poorly functioning testicles and gynecomastia (enlarged breasts).
> Triple X syndrome is characterized by a trisomy of the X-chromosome. It is 44 + XXX. In this syndrome the individual is a female having three X-chromosomes. Such individuals are also called Super females. Usually the females with triple X syndrome have normal sexual growth and they are fertile. Some of the symptoms of this syndrome are – delay in development of speech and language abilities, attention deficiency, learning disabilities such as dyslexia etc.

Therefore, the correct answer is C, i.e., Klinefelter’s Syndrome.

Note: In humans, the presence of Y-chromosome determines maleness and its absence determines femaleness. The female has two X-chromosomes (X X) and male has one X and one Y-chromosome (XY). Presence of one extra sex chromosome or absence of one sex chromosome results in several physical and behavioural changes.