Intrafamilial phenotypic variation in limb-girdle muscular dystrophy type 2C with compound heterozygous mutations.

Two Japanese-Brazilian siblings with type 2C limb girdle muscular dystrophy showed a maternal 521-T deletion in exon 6 and a larger paternal deletion of exon 6 in the gamma-sarcoglycan gene. One sib was ambulant at 29 years of age, whereas the other sib was confined to a wheelchair at the age of 12. Sarcoglycan staining of the muscle was reduced in both siblings but it did not correlate with the observed variability of the clinical severity.

Developmental expression of P0 mRNA and P0 protein in the sciatic nerve and the spinal nerve roots of the rat.

Expression of myelin P0 protein by myelinating Schwann cells in vivo is dependent on axonal influences. This report describes P0 gene expression during development of rat sciatic nerve and spinal nerve roots using Northern blotting, in situ hybridization and immunohistochemistry. We demonstrate that: (1) the appearance of P0 mRNA and P0 protein in Schwann cells during nerve development in the rat begins prenatally, at day 18 post-fertilization (E18); (2) P0 mRNA and P0 protein have essentially identical developmental profiles, and are expressed in Schwann cells that are many days prior to myelin formation; (3) initial P0 gene expression is greatest in Schwann cells at the periphery of nerve bundles and in Schwann cells in contact with motor axons; (4) the decline in P0 expression with nerve maturation is accompanied by a sharp decline in P0 message levels in most Schwann cells, but a small subpopulation of these cells continue to synthesize very high levels of P0 mRNA. This study provides data on myelin P0 protein gene expression and distribution during PNS development and adds further insights into the axonal influences controlling Schwann cell behaviour during myelination of the rat PNS.