Dept. of Mother-Child and Urologic Sciences, Sapienza University of Rome, Rome, Italy.
Dept. of Experimental Medicine, Sapienza University of Rome, Rome, Italy.
PLoS One. 2019 Oct 8;14(10):e0222838. doi: 10.1371/journal.pone.0222838. eCollection 2019.
Two novel and related pathogenic variants of the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene were structurally and functionally characterized. These alterations have not been previously described in literature. Two patients with diagnosis of Cystic Fibrosis (CF) based on the presence of one mutated allele, p.Phe508del, pathological sweat test and clinical symptoms were studied. To complete the genotypes of both patients, an extensive genetic and functional analysis of the CFTR gene was performed. Extensive genetic characterization confirmed the presence of p.Phe508del pathogenic variant and revealed, in both patients, the presence of an insertion of part of intron 10 in intron 9 of the CFTR gene, within the (TG)m repeat, with a variable poly-T stretch. The molecular lesions resulted to be very similar in both patients, with only a difference in the number of T in the poly-T stretch. The functional characterization at RNA level revealed a complete anomalous splicing, without exon 10, from the allele with the insertion of both patients. Consequently, the alleles with the insertions are expected not to contribute to the formation of a functional CFTR protein. Molecular and functional features of these alterations are compatible with the definition of novel CF-causing variants of the CFTR gene. This also allowed the completion of the genetic characterization of both patients.
两种新型且相关的囊性纤维化跨膜电导调节因子 (CFTR) 基因突变体的结构和功能特征进行了研究。这些改变以前在文献中没有描述过。对两个基于一个突变等位基因 p.Phe508del 的囊性纤维化 (CF) 诊断的患者进行了研究，该基因存在病理性汗试验和临床症状。为了完成两个患者的基因型，对 CFTR 基因进行了广泛的遗传和功能分析。广泛的遗传特征证实了 p.Phe508del 致病性变异体的存在，并在两个患者中均发现 CFTR 基因第 10 内含子内的部分插入第 9 内含子，插入点位于 (TG)m 重复序列内，带有可变的多 T 延伸。这两个患者的分子病变非常相似，只有多 T 延伸中的 T 数量不同。在 RNA 水平上的功能特征显示，两个患者的等位基因均存在完全异常的剪接，缺失了外显子 10。因此，插入的等位基因预计不会有助于功能性 CFTR 蛋白的形成。这些改变的分子和功能特征与 CFTR 基因的新型 CF 致病变体的定义相符。这也使得两个患者的遗传特征得以完成。
