RESUMEN
Acheiropodia, congenital limb truncation, is associated with homozygous deletions in the LMBR1 gene around ZRS, an enhancer regulating SHH during limb development. How these deletions lead to this phenotype is unknown. Using whole-genome sequencing, we fine-mapped the acheiropodia-associated region to 12 kb and show that it does not function as an enhancer. CTCF and RAD21 ChIP-seq together with 4C-seq and DNA FISH identify three CTCF sites within the acheiropodia-deleted region that mediate the interaction between the ZRS and the SHH promoter. This interaction is substituted with other CTCF sites centromeric to the ZRS in the disease state. Mouse knockouts of the orthologous 12 kb sequence have no apparent abnormalities, showcasing the challenges in modelling CTCF alterations in animal models due to inherent motif differences between species. Our results show that alterations in CTCF motifs can lead to a Mendelian condition due to altered enhancer-promoter interactions.
Asunto(s)
Factor de Unión a CCCTC/genética , Extremidades/embriología , Deformidades Congénitas del Pie/genética , Regulación del Desarrollo de la Expresión Génica , Deformidades Congénitas de la Mano/genética , Animales , Sitios de Unión/genética , Secuenciación de Inmunoprecipitación de Cromatina , Modelos Animales de Enfermedad , Embrión de Mamíferos , Elementos de Facilitación Genéticos/genética , Exones/genética , Femenino , Sitios Genéticos , Pruebas Genéticas , Proteínas Hedgehog/genética , Humanos , Intrones/genética , Masculino , Proteínas de la Membrana/genética , Ratones , Ratones Noqueados , Regiones Promotoras Genéticas/genética , Eliminación de Secuencia , Especificidad de la Especie , Secuenciación Completa del GenomaRESUMEN
We aimed to assess the current genetics practice to manage patients with Lynch syndrome (LS) across Latin America. A Latin American LS survey was sent out to 52 centres/registries, comprising a total of 12 countries from the region. Overall, 33 centres completed the survey, of which the oldest LS registry was established in 1992 in Sao Paulo (Brazil), and the youngest this year in San Jose (Costa Rica). In total, 87% (26/30) of the participating centres/registries belonging to the nine countries are performing genetic testing. Overall, 1352 suspected families were sequenced. Pathogenic variants were identified in 34% of the families, with slightly differing distribution of variants between females and males. Path_MLH1 variants were identified in 39% of females and 50% of males (p = 0.023), while path_MSH2 were identified in 37% of females and males, followed by path_PMS2 in 11% of females and 8% of males, path_MSH6 in 13% of females and 3% of males (p < 0.001) and path_EPCAM in 0.3% of females and 2% of males. In Latin America, 9 of 12 (75%) participating countries had implemented healthcare for LS. LS screening is inconsistently applied within Latin America healthcare systems because of structural differences in the healthcare systems between the countries.