Q9 of 26 Page 1

What is Aneuploidy? Write the karyotypes of an autosomal and sex chromosomal disorders in humans.

Failure of segeregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy.


There are 23 pairs of chromosomes in humans, out of which 22 pairs are autosomes and 1 pair is sex chromosome.


Autosomal disorders in humans –


Down’s syndrome is caused due to the presence of an additional copy of chromosome number 21 (trisomy of 21) resulting into a karyotype of 47.


Sex chromosomal disorders in humans –


Klinefelter’s Syndrome is caused due to the presence of an additional copy of X-chromosome (XXY) resulting into a karyotype of 47.


Turner’s syndrome is caused due to the absence of one of the X-chromosome resulting into a karyotype of 45.


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