Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s) ( aneuploidy)
Autosomes:-
Down’s Syndrome: The cause is the presence of an additional copy of the chromosome number 21 (trisomy of 21)
The affected individual is
• short statured with small round head,
• furrowed tongue and partially open mouth
• Palm is broad with characteristic palm crease.
• Physical, psychomotor and mental development is retarded
Sex chromosomes:-
Klinefelter’s Syndrome : This is caused due to the presence of an additional copy of Xchromosome resulting into a karyotype of 47, XXY.
Such an individual has overall masculine development
• has overall masculine development
• feminine development is also expressed by the development of breast/ Gynaecomastia). Such individuals are sterile.
