Alpha vs. gamma sarcoglycanopathy: DNA tests solve a case from Argentina.

Immunohistochemical and DNA results are described in a patient with sarcoglycanopathy. Immunostaining was comparatively normal for alpha-, attenuated for beta- and delta-, and markedly attenuated for gamma-sarcoglycan, thus sarcoglycanopathy was diagnosed, presumably a gamma-sarcoglycanopathy. Unexpectedly, two alpha-SGP-related pathogenic mutations were identified in compound heterozygosity in the SGCA gene: c.229C > T (p.Arg77Cys) in exon 3 and c.850C > T (p.Arg284Cys) in exon 7. These are discussed together with six additional changes detected in SGCB, SGCG and SGCD.

Human cytochrome c oxidase subunit VIb: characterization and mapping of a multigene family.

We report the isolation and sequence of a human heart cDNA coding for cytochrome c oxidase (COX) subunit VIb (COX VIb). This cDNA extends 50 bp upstream from the region coding for the mature peptide. By Northern analysis, a single transcript of approx. 550 nucleotides (nt) has been identified in six human tissues. Southern analysis of human genomic DNA demonstrates the presence of multiple loci that show high homology to the cDNA. These loci cosegregate with either five or six different human chromosomes in human-rodent somatic cell hybrids. Using the COX6b cDNA, genomic sequences representing two of these loci have been isolated and characterized. The nt sequence analysis suggests that both loci represent COX6b pseudogenes.

Sorsby fundus dystrophy. A family with the Ser181Cys mutation of the tissue inhibitor of metalloproteinases 3.

Sorbsy fundus dystrophy (SFD) is an autosomal dominant disorder that is characterized by bilateral loss of central vision secondary to choroidal neovascularization and/or pigment epithelial atrophy in the macula, with onset of visual symptoms usually in the fourth or fifth decade. Drusenlike changes may occur, with impaired dark adaptation and abnormal electroretinographic results.

Costello syndrome: report of a new case with choanal atresia and fatal outcome.

We describe a girl with motor and mental retardation, macrocephaly, a "coarse" face, choanal atresia, postnatal feeding difficulty, redundant skin with deep palmar and plantar creases, and histopathological evidence of altered elastic fibers, who died at the age of 11 months. We believe this represents another case of Costello syndrome. Lacking papillomata, she had choanal atresia and underwent a fatal outcome at an early age. The differential diagnosis of cutis laxa in association with postnatal growth retardation and developmental delay and with cardio-facio-cutaneous and Noonan syndromes is discussed.

A second gene for cerulean cataracts maps to the beta crystallin region on chromosome 22.

Congenital cataracts are one of the most common major eye abnormalities and often lead to blindness in infants. At least a third of all cases are familial. Within this group, highly penetrant, autosomal dominant forms of congenital cataracts (ADCC) are most common. ADCC is a genetically heterogeneous group of disorders, in which at least eight different loci have been identified for nine clinically distinct forms. Among these, Armitage et al. (Nature Genet. 9: 37-40, 1995) mapped a gene for cerulean blue cataracts to chromosome 17q24. Bodker et al. (Am. J. Med. Genet. 37: 54-59, 1990) described a large family with cerulean blue cataracts, in which the affected daughter of affected first cousins was presumed to be homozygous for the purported gene. We report linkage in this family to the region on chromosome 22q that includes two beta crystallin genes (CRYBB2, CRYBB3) and one pseudogene (CRYBB2P1). The affected female in question is homozygous at all markers.

A mosaic pattern of alopecia in the oral-facial-digital syndrome type I (Papillon-Léage and psaume syndrome).

We present an infant girl with oral-facial-digital syndrome type I, who had alopecia following the scalp lines of Blaschko, and we discuss the characteristics of alopecia in this syndrome.

Autosomal dominant cerulean cataract is associated with a chain termination mutation in the human beta-crystallin gene CRYBB2.

Congenital cataracts are a common major abnormality of the eye that frequently cause blindness in infants. At least a third of all cases are familial; autosomal dominant congenital cataract (ADCC) appears to be the most common familial form in the Western world. Cerulean cataracts have peripheral bluish and white opacifications in concentric layers with occasional central lesions arranged radially. Although the opacities may be observed during fetal development and childhood, usually visual acuity is only mildly reduced until adulthood, when lens extraction is generally necessary. We have been studying a family (ADCC-1) with cerulean blue ADCC, in which the affected daughter of a first cousin mating was presumed to be homozygous for the cataract gene. Recently, we mapped an ADCC gene in this family to a region of chromosome 22 containing three beta-crystallin genes. Here we report that a chain-termination mutation in CRYBB2 is associated with ADCC in this family.

Isoforms of mammalian cytochrome c oxidase: correlation with human cytochrome c oxidase deficiency.

We have reviewed the structure, function, and biogenesis of mammalian cytochrome c oxidase, examined the tissue-specific expression of isoforms of cytochrome c oxidase subunits in different mammals, and attempted to correlate the data with our knowledge of cytochrome c oxidase deficiency, illustrated by one particular patient. Cytochrome c oxidase was isolated from bovine tissues, and individual subunits examined by SDS-PAGE, N-terminal peptide sequencing, and antibody binding. Isoforms of subunits VIa, VIIa, and VIII were identified, manifesting one pattern of expression in heart and skeletal muscle, and another in liver, kidney, and brain. In rat heart and liver, only one form of subunit VIIa was identified. Northern analysis of bovine and rat tissues suggested that the tissue-specific expression of subunits VIa and VIII is regulated transcriptionally in liver, kidney, and brain, and posttranscriptionally in heart and skeletal muscle. In humans, antibody binding documented isoforms of subunits VIa and VIIa, with the pattern of expression in heart and skeletal muscle differing from that in liver, kidney, and brain; our data suggested that both isoforms of subunit VIa may be expressed in human heart. In a patient with cytochrome c oxidase deficiency, the clinical, morphologic, and biochemical manifestations were much more severe in heart than in skeletal muscle. Antibody binding suggested partial assembly of the enzyme in heart. These and other data suggest considerably more variability in the tissue-specific expression of isoforms of cytochrome c oxidase subunits than previously recognized.