Anomalies in sex chromosomes
- Due to monosomy (2n-1)
- The individual has 2n=45 chromosomes (44+X), instead of 46.
- One in every 3000 females birth is a victim
|Turner's syndrome Karyotype|
- Such persons are sterile females who have rudimentary ovaries, undeveloped breasts, small uterus, puffy fingers, short stature (less than 5 feet), webbed neck, abnormal intelligence, cardiovascular abnormalities and hearing impairment.
- Is due to trisomy of sex X chromosome
- Individual has47 chromosome (44+XXY).Such persons are sterile males with undeveloped testes, mental retardation, long limbs and with some female characteristics such as feminine pitched voice and enlarged breasts (Gynaecomastia)
- One in every 500 male births is the victim of this syndrome.
- Such individuals have 47 (44+XYY) chromosomes. Characterized by abnormal height, mental retardation and criminal bent of mind (Jacob’s syndrome or Criminal syndrome)
- Due to the over production of male sex hormones
- Frequency is 1 in 1000.
- Such individual have 47(44+XXX), 48(44+XXXX), or 49(44+XXXXX), chromosomes.
- These females are characterised by abnormal sexual development and mental retardation.
- The number of barr bodies is less than total number of X-chromosomes.
- The frequency at birth of 44+XXX is 1 in 1500