Sex Chromosomal disorders constitute 50% of the chromosomal disorders seen at birth. Klinefelter syndrome is more common (1 per 1000 births) as compared to Turner’s syndrome (1 per 3000 births).

Klinefelter’s syndrome
It accounts for 1-3% of infertile males. It is characterized by tall stature and small atrophic testes (less than 2cm in length or 6 ml in volume), scanty facial, pubic and axillary hair, X-chromatin positive buccal smear and XXY chromosomal constitution. The span (the distance between finger tips of out-stretched hands) is greater than the height, and lower segment greater than upper segment, (lower segment is the distance from heels to the upper end of pubic bone, and upper segment from the top of the skull to the upper end of pubic bone). The testosterone level ins the blood, is low or low normal and FSH and LH levels are increased. Almost half the patients have gynecomastia. The testes show atrophic and hyalinized seminiferous tubules and hypertrophic Leydig cells on biopsy.

Some patients with the above features may have more than two X-chromosomes. Further increase in the number of X-chromosomes increase the chance of mental retardation, as well as skeletal and somatic defects. Treatment consists of the administration of long acting testosterone to induce male characteristics during puberty. The dose has to be varied from 25 to 250 mg given intramuscularly once in three weeks. Azoospermia does not improve, though the physical features of the patient may change.

Turner’s syndrome
In Turner’s syndrome, the sex chromosome pattern is XO. such patients are X-chromatin negative. Mosaic patterns such as XO/XX and others are sometimes seen. Structural abnormalities such as deletion of parts of the X-chromosome may occur. Turner’s syndrome is characterized by short stature from birth (Adult height is about 141 cm), webbed and short neck, undeveloped breasts, scanty pubic hairs, hypoplastic uterus and the presence of fibrous streaks instead of ovaries. Often there is edema of the dorsum of the hands and feet at birth due to bypoplasia of lymphatic vessels. The face is triangular with depressed nose, large mouth, small chin and loose folds of skin below the eyelids. Epicanthic folds and high arched palate may be seen. The chest is shield-shaped with widely separated nipples and pectus excavatum. Large pigmented naevi, hyperconves or hypoplastic nails, cubitus valgus, clinodactyly, short metacarpals and increased dermatoglyphic ridges on fingers may occur. Other stigmata include coarctation of Aorta, ventricular septal defect and renal anomalies such as horse-shoe Kidney. there is no mental retardation. Verbal IQ is lower than the performance IQ.

Most patients are amenorrhoeic though some may show scanty periods. replacement therapy with Oestrogens and progesterone secondary sexual characters, Height does not improve with this form of therapy.

XYY syndrome
Presence of an extra Y chromosome confers mental subnormality and a violent or a criminal behavior. The majority have the karyptype XYY. they are generally from normal individuals, Radio-ulnar synostosis and cubitus valgus may be seen in some.

Sex Chromosomal Disorders – Klinefelter’s Syndrome, Turner’s Syndrome and XXY Syndrome

Tags: births, buccal smear, pubic, testes

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