Pathogenicity of the MYH7 H1904L mutation most likely results from disruption of myosin heavy chain assembly or stability of the sarcomeric protein. The MYH7 tail domain mutation results in an inclusion body myopathy with an apparent absence of hypertrophic cardiomyopathy usually associated with mutations of this gene.

Maternal uniparental disomy of chromosome 7 (mUPD7) has been reported in around 10% of cases of Silver-Russell syndrome (SRS). This suggests that at least one gene on chromosome 7 is imprinted and involved in the pathogenesis of this condition. One candidate is epidermal growth factor receptor (EGFR) which maps to chromosome 7p12, a region homologous to an imprinted region on mouse chromosome 11. Using a restriction fragment length polymorphism, biallelic expression of EGFR was found in a range of normal human fetal tissues. Expression was also demonstrated in fibroblasts and lymphoblasts from SRS patients with mUPD7. Thus no evidence that EGFR is imprinted was found, making its involvement in SRS unlikely. However, EGFR was shown to be widely expressed in the human fetus, evidence that this gene plays an important role in early development.

The HSP that this family had represents a novel genetic form of pure ARHSP as no other form of HSP (autosomal dominant or recessive) has been linked to chromosome 13.

The nucleotide sequence of a mitochondrial plasmid (2234 bp) in a diseased isolate of Ophiostoma novo-ulmi, and sequences of the mitochondrial DNA that overlap and flank the plasmid end-points, have been determined. The plasmid was shown to be derived from the O. novo-ulmi mitochondrial large subunit ribosomal RNA gene and contained most of intron 1, the whole of exon 2, and probably the first part of intron 2. Within intron 1 there is an open reading frame with the potential to encode a 323 amino-acid polypeptide which contained dodecapeptide sequences typical of RNA maturases and DNA endonucleases. The endpoints of the plasmid in the mtDNA were located within two 90-bp direct imperfect repeat sequences, one of which comprised the last 7 bp of exon 1 and the first 83 bp of intron 1 whilst the other comprised the last 7 bp of exon 2 and the first 83 bp of intron 2. It is proposed that the Ld plasmid was generated by intramolecular recombination between these two repeats with the crossover point probably within the last 15 bp.

By subtractive hybridization we have isolated a cDNA clone designated G90 from the small intestine. Expression analysis of G90 revealed high expression in small intestine, testis, kidney and lung. Lower expression was observed in heart, brain, liver, spleen and skeletal muscle. A transcript size of 1n5 kb is seen in all tissues ; however, in testis a second transcript of 1n3 kb was observed. Further analysis provided evidence that in the intestine and testis G90 is expressed only in non-dividing cells. In post-midgestation mouse embryos, G90 is expressed in the cochlea, in the nasal epithelium and in restricted areas of the brain. As assessed by mRNA in situ hybridization, G90 is not expressed in proliferating cells of the intestinal epithelium and in intestinal adenomas. Sequencing of G90 cDNA gave no open reading frame, indicating that G90 may be a functional mRNA. Mapping of G90 showed that it is located on mouse chromosome 6, close to the imprinted gene Mest. Subsequent analysis of the imprinting status revealed a strainspecific silencing of one allele in interspecific hybrids, but influence of parental sex could not be found.