What is XXY — Klinefelter syndrome ?

Kline­fel­ter syn­drome is also called XXY syn­drome or 47, XXY. This con­di­tion is char­ac­terised by the pres­ence of an extra X Chro­mo­somes in males instead of usu­al male geno­type XY, and is asso­ci­at­ed with sev­er­al phys­i­cal and devel­op­men­tal abnormalities. 

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Defect­ed males have small testes and pro­duce less restau­rant due to which phys­i­cal devel­op­ment is high­ly affect­ed and the devel­oped sev­er­al fem­i­nine characteristics.The grew taller than aver­age and Devel­op enlarge breast(gynaecomastia ) broad­er hips Less­er body hair Oligosper­mia and infer­til­i­ty­Gen­i­tal defect may also include unde­scend­ed testes and under­de­vel­oped penis (micrope­nis).

Chil­dren with kline­fel­ter syn­drome show delay in cog­ni­tive devel­op­ment learn­ing dis­abil­i­ties and dif­fi­cul­ties in speech and lan­guage development.

The fre­quen­cy of occur­rence of clsyn­drome in a pop­u­la­tion is about 1000 Male birth.

Kline­fel­ter syn­drome was iden­ti­fied symp­to­mati­cal­ly by Har­ry Kline­fel­ter in 1940, how­ev­er it wad in 1956 when it cause was attrib­uted to the pres­ence of an extra copy of X chromosomes. 

The inten­si­ty of symp­tom of kline­fel­ter syn­drome was among indi­vid­u­als. oth­er vari­ance of kline­fel­ter syn­drome also exist the very rare which may be char­ac­ter­ized by 48 , XXXY or 49 , XXXXY.

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In such cas­es the symp­toms are more severe caus­ing devel­op­men­tal delays Intel­lec­tu­al dis­abil­i­ties, Phys­i­cal abnor­mal­i­ties and Increased risk of disease.

The appear­ance of extra X chro­mo­some is due to mei­ot­ic abnor­mal­i­ty is occur­ring dur­ing male gamete formation.

A gamete with extra X chro­mo­somes may con­tribute to the addi­tion­al copy of X in zygote and fer­til­iza­tion with nor­mal gamete.

All the cells of an embryo will then receive this extra Copy And the male child will devel­op kline­fel­ter syndrome.

Mosaicism is also seen in this syn­drome in which the extra X chro­mo­somes come into exis­tence due to abnor­mal cell divi­sion dur­ing embry­on­ic development.

This results into 47,XXY con­di­tion only in some cells oth­er body cells being nor­mal (46, XY).