RESUMO
Inherited retinal diseases (IRDs), defined by dysfunction or progressive loss of photoreceptors, are disorders characterized by elevated heterogeneity, both at the clinical and genetic levels. Our main goal was to address the genetic landscape of IRD in the largest cohort of Spanish patients reported to date. A retrospective hospital-based cross-sectional study was carried out on 6089 IRD affected individuals (from 4403 unrelated families), referred for genetic testing from all the Spanish autonomous communities. Clinical, demographic and familiar data were collected from each patient, including family pedigree, age of appearance of visual symptoms, presence of any systemic findings and geographical origin. Genetic studies were performed to the 3951 families with available DNA using different molecular techniques. Overall, 53.2% (2100/3951) of the studied families were genetically characterized, and 1549 different likely causative variants in 142 genes were identified. The most common phenotype encountered is retinitis pigmentosa (RP) (55.6% of families, 2447/4403). The most recurrently mutated genes were PRPH2, ABCA4 and RS1 in autosomal dominant (AD), autosomal recessive (AR) and X-linked (XL) NON-RP cases, respectively; RHO, USH2A and RPGR in AD, AR and XL for non-syndromic RP; and USH2A and MYO7A in syndromic IRD. Pathogenic variants c.3386G > T (p.Arg1129Leu) in ABCA4 and c.2276G > T (p.Cys759Phe) in USH2A were the most frequent variants identified. Our study provides the general landscape for IRD in Spain, reporting the largest cohort ever presented. Our results have important implications for genetic diagnosis, counselling and new therapeutic strategies to both the Spanish population and other related populations.
Assuntos
Distrofias Retinianas/epidemiologia , Distrofias Retinianas/genética , Transportadores de Cassetes de Ligação de ATP/genética , Adulto , Idoso , Estudos de Coortes , Estudos Transversais , DNA/genética , Proteínas da Matriz Extracelular/genética , Proteínas do Olho/genética , Feminino , Testes Genéticos/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Mutação/genética , Miosina VIIa/genética , Linhagem , Periferinas/genética , Prevalência , Retinose Pigmentar/genética , Estudos Retrospectivos , Espanha/epidemiologiaRESUMO
Paramyotonia congenita (OMIM 168300) is a non-dystrophic myopathy caused by mutations in the SCN4A gene that sometimes can be confused with myotonia congenita. Another disease also caused by mutations in the gene SCN4A is called myotonia aggravated by potassium (OMIM 170500, 613345). It is estimated that more than 20% of patients with suspected myotonia congenita suffer paramyotonia congenita. The two related SCN4A phenotypes exhibit an autosomal dominant inheritance and are the result of mutations that cause an increase in the function of the protein coded by this gene. In this study we present a case of paramyotonia congenita in a family with several affected members and in which a mutation in the SCN4A gene was identified. Evolutionary conservation data and predictive algorithms of pathogenicity allow us to conclude that this DNA variant is the cause of the disease in this family.
Assuntos
Transtornos Miotônicos/genética , Canal de Sódio Disparado por Voltagem NAV1.4/genética , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Linhagem , Adulto JovemRESUMO
8-oxo-7,8-dihydro-2'-deoxyguanosine (8oxodG) is a major lesion resulting from oxidative stress and found in both DNA and dNTP pools. Such a lesion is usually removed from DNA by the Base Excision Repair (BER), a universally conserved DNA repair pathway. 8oxodG usually adopts the favored and promutagenic syn-conformation at the active site of DNA polymerases, allowing the base to hydrogen bonding with adenine during DNA synthesis. Here, we study the structural determinants that affect the glycosidic torsion-angle of 8oxodGTP at the catalytic active site of the family X DNA polymerase from Bacillus subtilis (PolXBs). We show that, unlike most DNA polymerases, PolXBs exhibits a similar efficiency to stabilize the anti and syn conformation of 8oxodGTP at the catalytic site. Kinetic analyses indicate that at least two conserved residues of the nucleotide binding pocket play opposite roles in the anti/syn conformation selectivity, Asn263 and His255 that favor incorporation of 8oxodGMP opposite dA and dC, respectively. In addition, the presence in PolXBs of Mn2+-dependent 3'-phosphatase and 3'-phosphodiesterase activities is also shown. Those activities rely on the catalytic center of the C-terminal Polymerase and Histidinol Phosphatase (PHP) domain of PolXBs and, together with its 3'-5' exonuclease activity allows the enzyme to resume gap-filling after processing of damaged 3' termini.
