A clinical description is given of a syndrome present in three postnatally and two prenatal‐ly detected cases with partial trisomy 16p, caused by a familial translocation t(16;21) (pll;q22). The most consistent features of this syndrome are: low birth weight, small head circumference, low‐set ears, palato(gnatho)schisis, micrognathia, thumb‐agenesis or hypoplasia, hypertonia, overlapping fingers, single umbilical artery, and psychomotor retardation. The clinical picture was identical to that described by Roberts & Duckett (1978) for a single case.

A balanced maternal chromosome translocation (9p24;21q214) resulted in two offspring with unbalanced karyotypes. One of these, a girl trisomic for both segment 9pter to 9p24 and segment 21pter to 21q214, was found to have a SOD-A activity not significantly different from those found in a group of five cases with trisomy 21. However, clinical evaluation of this girl revealed no symptoms of the Down syndrome. These findings suggest that, providing the gene dosage theory is correct, the gene for SOD-A is probably localized on chromosome 21 proximal to, or in, band q21.

The three main features of Meckel syndrome are encephalocele, polycystic kidneys, and polydactyly. Prenatal diagnosis of a fetus with Meckel syndrome was made in the 16th week of gestation by means of amniotic fluid alpha1 fetoprotein estimation. The indication for amniocentesis was a previous child with an occipital meningocele and polycystic kidneys. Interpretation of the alpha1-fetoprotein value (240 microgram/ml) was difficult due to fetal blood contamination. Prenatal diagnosis is indicated in any pregnancy following the birth of a child with only two major symptoms of Meckel syndrome.