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Different missense, nonsense and frameshift mutations in the GAN gene encoding gigaxonin have been described to cause giant axonal neuropathy, a severe early-onset progressive neurological disease with autosomal recessive inheritance. By oligonucleotide array CGH analysis, we identified a 57-131 kb microdeletion affecting this gene in a patient with developmental delay, ataxia, areflexia, macrocephaly, and strikingly frizzy hair. The microdeletion was inherited from the mother and mutation analysis revealed a paternally inherited missense mutation c.1456G>A in exon 9 on the other allele. Our findings illustrate the power of higher resolution array CGH studies and highlight the importance of considering copy number variations in autosomal recessive diseases., (© 2010 Wiley-Liss, Inc.)

Ciliopathies are an expanding group of rare conditions characterized by multiorgan involvement, that are caused by mutations in genes encoding for proteins of the primary cilium or its apparatus. Among these genes, CEP290 bears an intriguing allelic spectrum, being commonly mutated in Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS), Senior-Loken syndrome and isolated Leber congenital amaurosis (LCA). Although these conditions are recessively inherited, in a subset of patients only one CEP290 mutation could be detected. To assess whether genomic rearrangements involving the CEP290 gene could represent a possible mutational mechanism in these cases, exon dosage analysis on genomic DNA was performed in two groups of CEP290 heterozygous patients, including five JSRD/MKS cases and four LCA, respectively. In one JSRD patient, we identified a large heterozygous deletion encompassing CEP290 C-terminus that resulted in marked reduction of mRNA expression. No copy number alterations were identified in the remaining probands. The present work expands the CEP290 genotypic spectrum to include multiexon deletions. Although this mechanism does not appear to be frequent, screening for genomic rearrangements should be considered in patients in whom a single CEP290 mutated allele was identified.

Several mutations in mitochondrial transfer RNA (tRNA) genes can cause mitochondrial myopathy. We describe a young girl who presented with pronounced exercise intolerance. The anaerobic threshold and the maximal oxygen consumption were decreased. She had decreased complex I and IV enzyme activity and ragged red fibers on muscle biopsy. An A to G transition at nucleotide position 7526 in tRNA Aspartate (tRNA(Asp)) gene was heteroplasmic in several of the patient's tissues. We were unable to detect the mutation in muscle tissue from the patient's mother. This case adds a new genetic etiology for mitochondrial myopathy. It also illustrates for patients with combined deficiency of the complex I and IV enzyme activity the value of sequencing in the affected tissue muscle, and not only in blood, all mitochondrial tRNA genes including those not commonly affected, such as in this case mt tRNA(Asp)., ((c) 2005 Wiley-Liss, Inc.)

We investigated two siblings of a Spanish family presenting with congenital lactic acidosis. They had severe failure to thrive, liver dysfunction, and renal tubulopathy. An isolated biochemical complex III deficiency was detected in liver. A search for mutations in the human bc1 synthesis like (BCS1L) gene was undertaken. Direct sequencing revealed a missense mutation R45C and a nonsense mutation R56X, both located in exon 1 of BCS1L. The missense mutation in combination with a loss of function of the second allele is responsible for the isolated complex III deficiency in this family., (Copyright 2003 Wiley-Liss, Inc.)

A homozygous mutation in the flavoprotein (Fp) gene associated with complex II deficiency was demonstrated in a patient with consanguineous parents. She succumbed at 5(1/2) months of age following a respiratory infection. The c1664G-->A transition detected, predicted the substitution of the small uncharged glycine at position 555 by glutamic acid. Her clinical course was at variance with the Leigh syndrome in three previously reported patients due to Fp gene mutations. In this proband, CRM for flavoprotein as well as iron-containing protein (Ip) was decreased, CRM for the entire complex II (130 kDa) being reduced even more. This observation prompts speculation of a labile interaction between Ip and Fp polypeptides and of a key role of the amino acid at position 555 in the interacting domain., (Copyright 2003 Wiley-Liss, Inc.)