RESUMO
Recent studies suggest that transcript isoforms significantly overlap (approximately 60%) between brain tissue and Epstein-Barr virus-transformed lymphoblastoid cell lines (LCLs). Interestingly, 14 cohesion-related genes with variants that cause Cornelia de Lange Syndrome (CdLS) are highly expressed in the brain and LCLs. In this context, we first performed RNA sequencing of LCLs from 22 solved (with pathogenic variants) and 19 unsolved (with no confirmed variants) CdLS cases. Next, an RNA sequencing pipeline was developed using solved cases with two different methods: short variant analysis (for single-nucleotide and indel variants) and aberrant splicing detection analysis. Then, 19 unsolved cases were subsequently applied to our pipeline, and four pathogenic variants in NIPBL (one inframe deletion and three intronic variants) were newly identified. Two of three intronic variants were located at Alu elements in deep-intronic regions, creating cryptic exons. RNA sequencing with LCLs was useful for identifying hidden variants in exome-negative cases.
Assuntos
Síndrome de Cornélia de Lange , Infecções por Vírus Epstein-Barr , Proteínas de Ciclo Celular/genética , Síndrome de Cornélia de Lange/diagnóstico , Síndrome de Cornélia de Lange/genética , Síndrome de Cornélia de Lange/patologia , Herpesvirus Humano 4/genética , Humanos , Nucleotídeos , Fenótipo , Isoformas de Proteínas/genética , Análise de Sequência de RNARESUMO
Cornelia de Lange syndrome (CdLS) is a rare multisystem disorder with specific dysmorphic features. Pathogenic genetic variants encoding cohesion complex subunits and interacting proteins (e.g., NIPBL, SMC1A, SMC3, HDAC8, and RAD21) are the major causes of CdLS. However, there are many clinically diagnosed cases of CdLS without pathogenic variants in these genes. To identify further genetic causes of CdLS, we performed whole-exome sequencing in 57 CdLS families, systematically evaluating both single nucleotides variants (SNVs) and copy number variations (CNVs). We identified pathogenic genetic changes in 36 out of 57 (63.2 %) families, including 32 SNVs and four CNVs. Two known CdLS genes, NIPBL and SMC1A, were mutated in 23 and two cases, respectively. Among the remaining 32 individuals, four genes (ANKRD11, EP300, KMT2A, and SETD5) each harbored a pathogenic variant in a single individual. These variants are known to be involved in CdLS-like. Furthermore, pathogenic CNVs were detected in NIPBL, MED13L, and EHMT1, along with pathogenic SNVs in ZMYND11, MED13L, and PHIP. These three latter genes were involved in diseases other than CdLS and CdLS-like. Systematic clinical evaluation of all patients using a recently proposed clinical scoring system showed that ZMYND11, MED13L, and PHIP abnormality may cause CdLS or CdLS-like.
