The diagnosis is often made when the boy is 15 or 16 years ofage. At that point, the finding of the progressive developmentof pubic and axillary hair in the presence of testes that remaininfantile in volume should alert the clinician to the disorder. Adolescents and young adults with KS tend to be tall, with longlimbs. During adolescence or adulthood, gynecomastia occurs.
Because of failure of growth and maturation of the testes, males with KS have testosterone deficiency and failure to produce viable sperm. Low production of testicular testosterone results in failure to develop later secondary sexual characteristics, such as facial hair, deepening of the voice, and libido. In adulthood, osteopenia and osteoporosis develop. Because of these findings, testosterone supplementation is indicated.
Most men with KS are infertile because they produce few viable sperm. Through the use of isolation of viable sperm through testicular biopsy, coupled with in vitro fertilization and intracytoplasmic sperm injection, it is possible for men with KS to father children; all children born to these men using this technology have had a normal chromosome complement.
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TS is the only condition in which a monosomic conceptus survives to term; however, 99% of embryos with 45,X are spontaneously aborted. The most common aneuploidy found in conceptuses (accounting for 1.4%,), 45,X is seen in 13% of first-trimester pregnancy losses. Occurring in 1 in 3200 live-born females, TS is notable for its spectrum of relatively mild physical and developmental findings. Affected women tend to have normal intelligence and life expectancy.
Females with TS typically have a characteristic facial appearance with low-set, mildly malformed ears, triangular face, flattened nasal bridge, and epicanthal folds. There is webbing of the neck, with or without cystic hygroma, a shield-like chestwith widened internipple distance, and puffiness of the hands
Extremities Overlapping of fingers and toes (clinodactyly) Polydactyly Hypoplastic nails, hyperconvex nails
General Severe developmental delays and prenatal and postnatal growth retardation Renal abnormalities Nuclear projections in neutrophils Only 5% live >6 mo Limited hip abduction Clinodactyly and overlapping fingers; index over third, fifth over fourth Rocker-bottom feet Hypoplastic nails
Severe developmental delays and prenatal and postnatal growth retardation Premature birth, polyhydramnios Inguinal or abdominal hernias Only 5% live >1yr
ASD, Atrial septal defect; PDA, patent ductus arteriosus; VSD, ventricular septal defect.
sternum, rocker-bottom feet, hypoplastic nails, and characteristic clenching of fists—the second and fifth digits overlap the third and fourth digits (Table 49-1).
The third of the common trisomies, trisomy 13 (47,XX,+13 or 47,XY,+13) occurs in 1 in 12,000 live births. It is usually fatal in the first year of life; only 8.6% of infants survive beyond their first birthday.