Down syndrome in two siblings with 47,XY,+21 and 46,XY/46,XY,-21,+t(21q;21q).

This is the first report in the literature of siblings affected with Down syndrome; one sibling had a nondisjunction of chromosome 21 and the other a (21q;21q) translocation.

Heterozygosity for phosphodiester glycosidase deficiency: a novel human mutation of lysosomal enzyme processing.

We have carried out studies on the fibroblasts of III-3, a clinically normal Lebanese individual previously reported to have abnormally high plasma lysosomal enzyme levels. Mannose-6-phosphate (man-6-P) receptors in III-3 fibroblasts were found to be functioning normally, but the cells had only half normal levels of phosphodiester glycosidase activity. Pinocytosis of III-3 fibroblast secreted beta-hexosaminidase B (hex B) into Sandhoff disease fibroblasts was 18% of control, and the apparent KD for binding of III-3 hex B to man-6-P receptors was 3.

Five related Lebanese individuals with high plasma lysosomal hydrolases: a new defect in mannose-6-phosphate receptor recognition?

Five healthy related individuals in 3 generations of a Lebanese family have been found to have highly elevated plasma lysosomal enzyme levels inherited as a dominant Mendelian trait. The same enzymes in other extracellular fluids were within normal limits. While the pattern and extent of plasma enzyme elevation was similar to that found in mucolipidoses II and III, the physicochemical properties of the elevated enzymes were different from those of both control and I-cell disease plasma.

Interstitial deletion of band q12 of chromosome 5.

A six-months-old girl is presented with psychomotor retardation and multiple congenital malformations. The karyotype done on peripheral blood lymphocytes and skin fibroblasts was found to be 46,XX del(5)( q11q13 ). The parents are consanguineous.