@article {467, title = {Re-evaluation casts doubt on the pathogenicity of homozygous USH2A p.C759F.}, journal = {Am J Med Genet A}, volume = {167}, year = {2015}, month = {2015 Jul}, pages = {1597-600}, abstract = {

Mutations in USH2A are a common cause of Retinitis Pigmentosa (RP). Among the most frequently reported USH2A variants, c.2276G>T (p.C759F) has been found in both affected and healthy individuals. The pathogenicity of this variant remains controversial since it was detected in homozygosity in two healthy siblings of a Spanish family (S23), eleven years ago. The fact that these individuals remain asymptomatic today, prompted us to study the presence of other pathogenic variants in this family using targeted resequencing of 26 retinal genes in one of the affected individuals. This approach allowed us to identify one novel pathogenic homozygous mutation in exon 13 of PDE6B (c.1678C>T; p.R560C). This variant cosegregated with the disease and was absent in 200 control individuals. Remarkably, the identified variant in PDE6B corresponds to the mutation responsible of the retinal degeneration in the naturally occurring rd10 mutant mice. To our knowledge, this is the first report of the identification of the rd10 mice mutation in a RP family. These findings, together with a review of the literature, support the hypothesis that homozygous p.C759F mutations are not pathogenic and led us to exclude the implication of p.C759F in the RP of family S23. Our results indicate the need of re-evaluating all families genetically diagnosed with this mutation.

}, keywords = {Base Sequence, Cyclic Nucleotide Phosphodiesterases, Type 6, Extracellular Matrix Proteins, Gene Library, Humans, Molecular Sequence Data, Mutation, Missense, Pedigree, Retinitis pigmentosa, Sequence Analysis, DNA, Spain}, issn = {1552-4833}, doi = {10.1002/ajmg.a.37003}, author = {Pozo, Mar{\'\i}a Gonz{\'a}lez-Del and Bravo-Gil, Nereida and M{\'e}ndez-Vidal, Cristina and Montero-de-Espinosa, Ignacio and Mill{\'a}n, Jos{\'e} M and Dopazo, Joaquin and Borrego, Salud and Anti{\v n}olo, Guillermo} } @article {490, title = {Novel RP1 mutations and a recurrent BBS1 variant explain the co-existence of two distinct retinal phenotypes in the same pedigree.}, journal = {BMC Genet}, volume = {15}, year = {2014}, month = {2014 Dec 14}, pages = {143}, abstract = {

BACKGROUND: Molecular diagnosis of Inherited Retinal Dystrophies (IRD) has long been challenging due to the extensive clinical and genetic heterogeneity present in this group of disorders. Here, we describe the clinical application of an integrated next-generation sequencing approach to determine the underlying genetic defects in a Spanish family with a provisional clinical diagnosis of autosomal recessive Retinitis Pigmentosa (arRP).

RESULTS: Exome sequencing of the index patient resulted in the identification of the homozygous BBS1 p.M390R mutation. Sanger sequencing of additional members of the family showed lack of co-segregation of the p.M390R variant in some individuals. Clinical reanalysis indicated co-ocurrence of two different phenotypes in the same family: Bardet-Biedl syndrome in the individual harboring the BBS1 mutation and non-syndromic arRP in extended family members. To identify possible causative mutations underlying arRP, we conducted disease-targeted gene sequencing using a panel of 26 IRD genes. The in-house custom panel was validated using 18 DNA samples known to harbor mutations in relevant genes. All variants were redetected, indicating a high mutation detection rate. This approach allowed the identification of two novel heterozygous null mutations in RP1 (c.4582_4585delATCA; p.I1528Vfs*10 and c.5962dupA; p.I1988Nfs*3) which co-segregated with the disease in arRP patients. Additionally, a mutational screening in 96 patients of our cohort with genetically unresolved IRD revealed the presence of the c.5962dupA mutation in one unrelated family.

CONCLUSIONS: The combination of molecular findings for RP1 and BBS1 genes through exome and gene panel sequencing enabled us to explain the co-existence of two different retinal phenotypes in a family. The identification of two novel variants in RP1 suggests that the use of panels containing the prevalent genes of a particular population, together with an optimized data analysis pipeline, is an efficient and cost-effective approach that can be reliably implemented into the routine diagnostic process of diverse inherited retinal disorders. Moreover, the identification of these novel variants in two unrelated families supports the relatively high prevalence of RP1 mutations in Spanish population and the role of private mutations for commonly mutated genes, while extending the mutational spectrum of RP1.

}, keywords = {Bardet-Biedl Syndrome, Base Sequence, Case-Control Studies, DNA Mutational Analysis, Eye Proteins, Genes, Recessive, Genetic Association Studies, Humans, Microsatellite Repeats, Microtubule-Associated Proteins, Mutation, Missense, Pedigree, Phenotype, Retina, Retinitis pigmentosa}, issn = {1471-2156}, doi = {10.1186/s12863-014-0143-2}, author = {M{\'e}ndez-Vidal, Cristina and Bravo-Gil, Nereida and Gonz{\'a}lez-del Pozo, Mar{\'\i}a and Vela-Boza, Alicia and Dopazo, Joaquin and Borrego, Salud and Anti{\v n}olo, Guillermo} } @article {536, title = {Mutation screening of multiple genes in Spanish patients with autosomal recessive retinitis pigmentosa by targeted resequencing.}, journal = {PLoS One}, volume = {6}, year = {2011}, month = {2011}, pages = {e27894}, abstract = {

Retinitis Pigmentosa (RP) is a heterogeneous group of inherited retinal dystrophies characterised ultimately by the loss of photoreceptor cells. RP is the leading cause of visual loss in individuals younger than 60 years, with a prevalence of about 1 in 4000. The molecular genetic diagnosis of autosomal recessive RP (arRP) is challenging due to the large genetic and clinical heterogeneity. Traditional methods for sequencing arRP genes are often laborious and not easily available and a screening technique that enables the rapid detection of the genetic cause would be very helpful in the clinical practice. The goal of this study was to develop and apply microarray-based resequencing technology capable of detecting both known and novel mutations on a single high-throughput platform. Hence, the coding regions and exon/intron boundaries of 16 arRP genes were resequenced using microarrays in 102 Spanish patients with clinical diagnosis of arRP. All the detected variations were confirmed by direct sequencing and potential pathogenicity was assessed by functional predictions and frequency in controls. For validation purposes 4 positive controls for variants consisting of previously identified changes were hybridized on the array. As a result of the screening, we detected 44 variants, of which 15 are very likely pathogenic detected in 14 arRP families (14\%). Finally, the design of this array can easily be transformed in an equivalent diagnostic system based on targeted enrichment followed by next generation sequencing.

}, keywords = {Alleles, DNA Mutational Analysis, Exons, Genetic Variation, Genome, Hispanic or Latino, Humans, Introns, Language, mutation, Mutation, Missense, Oligonucleotide Array Sequence Analysis, Polymerase Chain Reaction, Reproducibility of Results, Retinitis pigmentosa, United States}, issn = {1932-6203}, doi = {10.1371/journal.pone.0027894}, author = {Gonz{\'a}lez-del Pozo, Mar{\'\i}a and Borrego, Salud and Barrag{\'a}n, Isabel and Pieras, Juan I and Santoyo, Javier and Matamala, Nerea and Naranjo, Bel{\'e}n and Dopazo, Joaquin and Anti{\v n}olo, Guillermo} }