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The autosomal dominant progressive bifocal chorioretinal atrophy (PBCRA) disease locus has been mapped to chromosome 6q14–16.2 which overlaps the North Carolina Macular Dystrophy (NCMD) locus MCDR1. NCMD is a non‐progressive developmental macular dystrophy, in which variants upstream of PRDM13 have been implicated. Whole genome sequencing was performed to interrogate structural variants (SVs) and single nucleotide variants (SNVs) in eight individuals, six affected individuals from two families with PBCRA and two individuals from an additional family with a related developmental macular dystrophy. A SNV (chr6:100,046,804 T > C), located 7.8 kb upstream of the PRDM13 gene, was shared by all PBCRA‐affected individuals in the disease locus. Haplotype analysis suggested that the variant arose independently in the two families. The two affected individuals from family 3, were screened for rare variants in the PBCRA and NCMD loci. This revealed a de novo variant in the proband, 21 bp from the first SNV (chr6:100,046,783 A > C). This study expands the non‐coding variant spectrum upstream of PRDM13 and suggests altered spatio‐temporal expression of PRDM13 as a candidate disease mechanism in the phenotypically distinct but related conditions, NCMD and PBCRA.

Although over 150 unique mutations affecting the coding sequence of CHM have been identified in patients with the X-linked chorioretinal disease choroideremia (CHM), no regulatory mutations have been reported, and indeed the promoter has not been defined. Here, we describe two independent families affected by CHM bearing a mutation outside the gene's coding region at position c.-98: C>A and C>T, which segregated with the disease. The male proband of family 1 was found to lack CHM mRNA and its gene product Rab escort protein 1, whereas whole-genome sequencing of an affected male in family 2 excluded the involvement of any other known retinal genes. Both mutations abrogated luciferase activity when inserted into a reporter construct, and by further employing the luciferase reporter system to assay sequences 5' to the gene, we identified the CHM promoter as the region encompassing nucleotides c.-119 to c.-76. These findings suggest that the CHM promoter region should be examined in patients with CHM who lack coding sequence mutations, and reveals, for the first time, features of the gene's regulation.

Retinal dystrophies are a heterogeneous group of disorders of visual function leading to partial or complete blindness. We report the genetic basis of an unusual retinal dystrophy in five families with affected females and no affected males. Heterozygous missense variants were identified in the X-linked PRPS1 gene: c.47C > T, p.(Ser16Phe); c.586C > T, p.(Arg196Trp); c.641G > C, p.(Arg214Pro) and c.640C > T, p.(Arg214Trp). Missense variants in PRPS1 are usually associated with disease in male patients, including Arts Syndrome, Charcot-Marie-Tooth and non-syndromic sensorineural deafness. In our study families, affected females manifested a retinal dystrophy with inter-ocular asymmetry. Three unrelated females from these families had hearing loss leading to a diagnosis of Usher Syndrome. Other neurological manifestations were also observed in three individuals. Our data highlight the unexpected X-linked inheritance of retinal degeneration in females caused by variants in PRPS1, and suggest that tissue specific skewed X-inactivation or variable levels of PRS-I deficiency are the underlying mechanism(s). We speculate that the absence of affected males in the study families suggests that some variants may be male embryonic lethal when inherited in the hemizygous state. The unbiased nature of next generation sequencing enables all possible modes of inheritance to be considered for association of gene variants with novel phenotypic presentation. This article is protected by copyright. All rights reserved

Although over 150 unique mutations affecting the coding sequence of CHM have been identified in patients with the X-linked chorioretinal disease choroideremia (CHM), no regulatory mutations have been reported, and indeed the promoter has not been defined. Here, we describe two independent families affected by CHM bearing a mutation outside the gene's coding region at position c.-98: CA and CT, which segregated with the disease. The male proband of family 1 was found to lack CHM mRNA and its gene product Rab escort protein 1, whereas whole-genome sequencing of an affected male in family 2 excluded the involvement of any other known retinal genes. Both mutations abrogated luciferase activity when inserted into a reporter construct, and by further employing the luciferase reporter system to assay sequences 5' to the gene, we identified the CHM promoter as the region encompassing nucleotides c.-119 to c.-76. These findings suggest that the CHM promoter region should be examined in patients with CHM who lack coding sequence mutations, and reveals, for the first time, features of the gene's regulation.

Ectopia lentis (EL) is genetically heterogeneous with both autosomal-dominant and -recessive forms. The dominant disorder can be caused by mutations in FBN1, at the milder end of the type-1 fibrillinopathies spectrum. Recently in a consanguineous Jordanian family, recessive EL was mapped to locus 1q21 containing the ADAMTSL4 gene and a nonsense mutation was found in exon 11 (c.1785T>G, p.Y595X). In this study, 36 consecutive probands with EL who did not fulfill the Ghent criteria for MFS were screened for mutations in FBN1 and ADAMTSL4. Causative FBN1 mutations were identified in 23/36 (64%) of probands while homozygous or compound heterozygous ADAMTSL4 mutations were identified in 6/12 (50%) of the remaining probands. Where available, familial screening of these families confirmed the mutation co-segregated with the EL phenotype. This study confirms that homozygous mutations in ADAMTSL4 are associated with autosomal-recessive EL in British families. Furthermore; the first compound heterozygous mutation is described resulting in a PTC and a missense mutation in the PLAC (protease and lacunin) domain. The identification of a causative mutation in ADAMTSL4 may allow the exclusion of Marfan syndrome in these families and guide the clinical management, of particular relevance in young children affected by EL. © 2010 Wiley-Liss, Inc.

Mutations in the FBN1 gene have been characterised in patients affected by Marfan syndrome and Marfan-related disorders. Starting with genomic DNA, we analysed the FBN1 gene using PCR, SSCP and/or dHPLC analysis, and automatic sequencing of abnormal bands/peaks, in a consecutive series of 508 patients, of which 22 were children less than 5 years old. Our results are comparable with those reported by other groups. In this study we observed 193 mutations, 126 of which previously unreported. A total of 331 relatives (including 51 infants) of 120 probands for whom a family mutation had been identified here or elsewhere, were tested for the presence of that particular mutation. In addition, 4 prenatal tests were carried out. The identification of a mutation allows for early diagnosis, prognosis, genetic counselling, preventive management of carriers and reassurance for unaffected relatives. The importance of knowing in advance the location of the putative family mutation is highlighted by its straightforward application to prenatal and postnatal screening. © 2007 Wiley-Liss, Inc.