Question

List any four symptoms shown by a Down’s syndrome/Turner’s syndrome/Klinefelter’s syndrome affected child. Explain the cause of the disorder.

Answer 1

Down’s syndrome is caused by the presence of an extra (third) chromosome 21, resulting in a total of 47 chromosomes instead of the normal 46. This is due to non-disjunction during gamete formation. Affected children show characteristic symptoms such as mental retardation, prominent foreheads, flattened nasal bridge, habitually open mouth with a large protruding tongue, and a characteristic skin fold at the corner of the eye. They also often have a short, stocky body and may suffer from congenital heart defects.

Turner’s syndrome is caused by monosomy of the X chromosome (XO type), where a female has only one X chromosome instead of two. This chromosomal abnormality results in sterile immature females with poorly developed ovaries. Symptoms include a webbed neck, broad chest with underdeveloped breasts, short stature, and below average intelligence. These individuals also show the presence of short fourth metacarpal and metatarsal bones.

Klinefelter’s syndrome is caused by the presence of an extra X chromosome in males (XXY), resulting in a total of 47 chromosomes. These individuals are phenotypically male but have underdeveloped testes, sparse body hair, some degree of breast development, and long limbs. They often exhibit mental deficiency and are sterile.