Sex Chromosomal Abnormalities
Human beings have 46 chromosomes of which 44 are autosomes and 2 are sex chromosomes. The two sex chromosomes determine if the baby is going to be a boy or a girl. These sex chromosomes are called X and Y. Females have 2 X chromosomes and males have one X chromosome and one Y chromosome. During fertilization the following takes place.
X (sperm) + X (ovum) = XX (Female)
Y (sperm) + X (ovum) = XY (Male)
There can be some defect in the number of sex chromosomes inherited from the parents, giving rise to sex chromosomal aneuploidy. The incidence of sex chromosomal aneuploidy is 1 in 400 in males and 1 in 650 in females
Sex Chromosomal Abnormalities are conditions that are compatible with survival unlike other chromosomal abnormalities. These disorders too can be detected through prenatal screening as in the case of Down syndrome. Diagnosis can be confirmed by a karyotype using a blood sample.
| Name | Incidence | Causes | Clinical features | Treatment |
| Turner syndrome | 1 in 2,500 to 5,000 | Presence of only one X chromosome instead of two | Lack of proper sexual development, proportionate short stature, improper ovarian development, broad-webbed neck, broad and shield like chest, structural defects of the heart and kidney, triangle-shaped face, posteriorly turned ears | No Treatment Available |
| Klinefelter Syndrome | 1 in 1,000 | Presence of an extra X chromosome in the male | Taller than average, small testis, sterility of the affected male, low I.Q, gynaecomastia, males with the condition are prone for breast cancer. | Removal of excess breast tissue can be carried out.Testosterone therapy is usually given. |
| Super females | 1 in 1,000 | Presence of an three X chromosomes in the female than the normal 2 | Tall and well built figure, mild mental retardation, the degree of mental retardation and physical abnormality increases with each X chromosome, sterility, and menstrual abnormalities. | Correction of symptoms or abnormalities associated with the condition |
| 47, XYY Karyotype | Normal population: 1 in 1,000 Tihar Jail: 1 in 30 | Presence of an extra Y chromosome in the normal male | Low level of I.Q, taller than average, violent behaviour, criminal tendency, behavioral problems such as attention deficit disorder, hyperactivity, aggressiveness. | No treatment |
