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We have previously reported a dystrophin-related locus (DMDL for Duchenne muscular dystrophy-like) on human chromosome 6 that maps close to the dy mutation on mouse chromosome 10. Here we show that this gene is expressed in a wide range of tissues at varying levels. The transcript is particularly abundant in several human fetal tissues, including heart, placenta, and intestine. Studies with antisera raised against a DMDL fusion protein identify a 400,000 Mr protein in all mouse tissues tested, including those of mdx and dy mice. Unlike the dystrophin gene, the DMDL gene transcript is not differentially spliced at the 3' end in either fetal muscle or brain.

The campomelic syndrome is a skeletal dysplasia of unknown aetiology which is apparent at birth and is characterized by bilateral bowing of the tibiae, clubfoot and other multiple congenital abnormalities. Up to 50% of cases are either stillborn or die within 24 hours of birth in respiratory distress. With a few exceptions, the remainder die within 10 months. The patient in this report demonstrated characteristic features of the syndrome which were detected antenatally by ultrasound and confirmed after delivery. The apparently female infant died 2 hours postpartum in respiratory distress, but was subsequently found to have a 46,XY chromosome constitution. Autopsy and postmortem radiographs revealed multiple congenital abnormalities consistent with the campomelic syndrome. The findings in this case are discussed and the possibility of antenatal diagnosis is raised.

Nine markers from the pericentromeric region of chromosome 17 were typed in 16 British and five South African families with neurofibromatosis type 1 (NF1). The markers--p17H8, pHHH202, and EW204--were linked to NF1 at recombination fractions less than 1%. No evidence of locus heterogeneity was detected. Inspection of recombinant events in families informative for several markers suggests that the NF1 gene is located between the markers EW301 (cen-p11.2) and EW206 (cen-q12) and possibly distal to pHHH202 (q11.2-q12).

Ninety-five members of three South African Indian families were examined for neurofibromatosis (NF) and 45 were deemed to be affected in terms of accepted diagnostic criteria. Analysis of the pedigrees revealed autosomal dominant inheritance with full penetrance. The absence of macromelanosomes in skin biopsies of café-au-lait macules and the failure to detect Lisch nodules (hamartomas of the iris) in this population group raises further evidence that NF might be a heterogeneous condition. The potential importance of heterogeneity in molecular linkage studies is emphasised.