Fragile site at 12q13 associated with phenotypic abnormalities.

A dysmorphic 3 year old boy with severe psychomotor retardation is described. His karyotype was 45,XY,t(13q;14q)rob, fra (12q13). The relationship between fra(12q13) and the clinical picture is discussed.

Regional mapping of hexokinase-1 within the short arm of chromosome 10.

Hexokinase-1 (HK1) activity was determined in red cells of 5 patients with partial duplications of chromosome 10, all of which involved the 10p region. In 4 patients the levels of HK1 activity were higher than the mean activity of controls, strongly indicating a triplex dosage effect. The most likely regional assignment for HK1 would appear to be 10p11.

Isodicentric X chromosome in a woman with characteristics of gonadal dysgenesis.

This paper presents a female patient with primary amenorrhea in whose karyotype an aberrant X chromosome was present. The chromosome resulted from the fusion of two X chromosomes at distal parts of the long arm and from the loss of the segment q24 leads to qter. The clinical and cytogenetic picture is compared with that of patients with the same aberration reported by other authors.