Autosomal and Sex chromosome abnormalities

Sex chromosome anomalies Sex Chromosome Abnormalities Pattern / Name Characteristics Incidence Treatment XYY Male; tall stature; tendency to low IQ, especially verbal 1 in 1,000 male births No special treatment XXX (triple X) Female; normal appearance, menstrual irregularities, learning disorders, mental retardation 1 in 1,000 female births Special education XXY (Kleinfelter) Male, sterility, underdeveloped secondary sex characteristics, small testes, learning disorders Hormone therapy, special education XO (Turner) Female, short stature, webbed neck, impaired spatial abilities, no menstruation, sterility, underdeveloped sex organs, incomplete development of secondary sex characteristics 1 in 3,500 female births Fragile X Minor-to-severe mental retardation; symptoms, which are more severe in males, include delayed speech and motor development, speech impairments, and hyperactivity; the most common inherited form of mental retardation 1 in 1,200 male births; 1 in 2,000 female births Educational and behavioral therapies when needed

Sex chromosomes abnormalities KLINEFLETER SYNDROME A male with XXY chromosomes Exhibits some female characteristics Such as enlarged breasts and high pitched voice TURNERS SYNDROME A female with XO exhibits a short stature, short neck, and broad chest with immature sex organs

XYY If in meiosis II the Y chromosome does not separate and is passed on to a boy the sex chromosomes will be XYY. Boys with this are unusually tall but have normal fertility. Studies have also shown that these men tend to be more violent than a XY male.

How does it happen? Non-disjunction can result in abnormalities in the number of sex chromosome. Both Klinefelter and Turners result from nondisjunction of either the male or female gamete. The disjunction of the female gametes can result in a Triple X female

Down Syndrome Down syndrome is a chromosomal abnormality of the 21th chromosome. It is known as Trisomy 21 since nondisjunction of a faulty cell division results in an embryo with three number 21 chromosomes instead of  two. People with down syndrome are usually mentally retarded, shorter, have a larger head and a short life span (usually about 30 years).

Down syndrome- Prior to, or at, conception, a pair of number 21 chromosomes, in either the sperm or the egg, fail to separate Karyotype of down syndrome