Mention any two autosomal genetic disorders with their symptoms.Write short notes on: (1) Down's Syndrome (II) Phenylketonuria (III) Klinefelter's Syndrome.

Ans. The autosomal genetic disorders are:

(i) Down's Syndrome:-  This genetic 

disorder is caused due to the presence

 of an additional copy of the chromosome number 21, a trisomy (2n + 1) type aneuploidy. 

This was first described by Langdon 

Down (1866). The affected child is short statured with small round head, habitually open mouth, protruding furrowed tongue.

 Palm is broad with characteristic palm crease, short neck, Mangolian eyelid fold and retarded mental development.

(ii) Phenylketonuria:-  It is a type of autosomal recessive trait arise due

 to mutation. This causes inborn error

of metabolism. The affected individual

lacks an enzyme that converts the 

amino acid phenylalanine into tyrosine. 

As a result of this phenylalanine is accumulated and converted into phenylpyruvic acid and other derivatives. Accumulation of these in brain causes in mental retardation. These are also excreted through urine due to their poor absorption by kidney.

(iii) Klinefelter's Syndrome:- This genetic disorder is caused due to the presence

 of an additional copy of X-chromosome resulting into 47 chromosomes i.e., 44 Autosomes + XXY. 

While Turner's Syndrome is caused due to the absence of one of the X-chromosome resulting into 45 chromosomes i.e., 44 Autosomes + XO. 

Klinefelter's Syndrome individual has tall stature with masculine development. However, well-developed feminine breast i.e., Gynaecomastia is also present.

इन्हे भी पढ़िए :-

Explain the term incomplete dominance.