Karyotyping of at risk fetuses by cordocentesis in advanced gestation.

Fetal blood obtained by cordocentesis was cultured to obtain rapid karyotypes of fetuses at risk during the late second trimester. Ninety nine fetal blood samples were studied for chromosomal abnormalities. The commonest indications for the procedure were abnormalities detected on ultrasonography (47.7%), and previous child with Down syndrome. Analysis of the 67 successful cultures showed four (5.9%) karyotypic abnormalities. The technique proved helpful in the obstetrical management of at risk fetuses.

A clinical and cytogenetic study of Turner syndrome.

Forty five case of Turner syndrome diagnosed in the Genetics Clinic, between January 1986 and December 1993, were analyzed. The most commonly observed karyotype was 45, X (44.4%), followed by 45, X/46, XX mosaicism (24.4%). Less frequently demonstrated karyotypes were 45, X/46, X, i (Xq) mosaicism and 46, X, i (Xq) (13.3%). Mosaicism for chromosome was seen in 6.7% of patients. Patients with 45, X karyotype had short stature (85%), dysmorphic facies (60%), delayed appearance of secondary sexual characters (100%) and primary amennorhea (100%). Those with 45, X/46, XX mosaicism were less often dysmorphic and presented with either primary or secondary amenorrhea. Patients with 45, X karyotype were younger at diagnosis and had a significantly shorter mean adult height than those with 45, X/46, XX mosaicism. The phenotype in patients with other karyotypic abnormalities was similar to the 45, X group. Short stature and primary or secondary amenorrhea occurring together in a female strongly suggests the possibility of Turner syndrome, which should be confirmed by chromosomal analysis.