DIAGNOSIS OF MEROSIN (LAMININ-2) DEFICIENT CONGENITAL MUSCULAR-DYSTROPHY BY SKIN BIOPSY

Background The alpha 2 chain of laminin-2 (merosin), encoded by a gene on chromosome 6q22, is deficient in about half the cases of congenita l muscular dystrophy. Diagnosis of this condition has relied on immuno cytochemical analysis of the alpha 2 chain in muscle biopsy specimens. We have observed that normal skin also expresses laminin alpha 2 in t he basement membrane at the junction of the dermis and epidermis. Here we have investigated laminin alpha 2 deficiency in skin biopsy specim ens from two patients with congenital muscular dystrophy. Participants Two patients with severe congenital muscular dystrophy gave informed consent to a shin biopsy. The girl was aged 10 and the boy was aged 7. The specimens were labelled with a commercially available mouse monoc lonal antibody and a rat monoclonal antibody (4H8-2), which recognise an 80 and a 380 kDa fragment of the alpha 2 chain, respectively. The a ntibodies were visualised by standard methods. A muscle biopsy specime n was available for each case, and was processed with the skin biopsy samples (from the girl a few months previously, from the boy at age 14 days). Skin biopsies were done on four controls with normal expressio n of laminin alpha 2 on their skeletal muscle fibres. Findings We did not detect laminin alpha 2 in skin specimens from either case, althoug h the controls were positive. The muscle biopsy specimens from the gir l showed a few fibres, with traces of laminin alpha 2; those from the boy showed no laminin alpha 2. Interpretation Skin biopsy specimens wi ll provide a useful alternative to muscle biopsy samples for the asses sment of laminin-2 (merosin) status in congenital muscular dystrophy.