A novel homozygous RTEL1 variant in a consanguineous Lebanese family: phenotypic heterogeneity and disease anticipation

AbstractPhenotypic heterogeneity is often observed in patients with telomeropathies caused by pathogenic variants in telomere biology genes. However, the roles of recessive variants in these different phenotypes are not fully characterized. Our goal is to describe the biological roles of a novel homozygousRTEL1 variant identified in a consanguineous Lebanese family with unusual presentation of telomeropathies. A proband was screened for germline variants in telomere biology genes by whole exome sequencing. Leukocytes ’ telomere length was measured in the proband and eight relatives. We identified a novel homozygous p.E665KRTEL1 variant in the proband, his mother, and seven siblings that associated with telomere shortening and a broad spectrum of clinical manifestations, ranging from mild unspecific findings to severe phenotypes. Consanguinity in at least three family generations led to increased frequency of the homozygous p.E665K variant in the youngest generation and progressive telomere shortening. The increased frequency of the homozygousRTEL1 variant due to consanguinity in this Lebanese family allowed us to infer novel behaviors of recessiveRTEL1 variants, as the expressivity and penetrance of this gene are very heterogenous between inter- and intra-generations. Progressive telomere shortening was associated with disease anticipation, first reported in recessive autosomal telomeropathies. Both genetic testing and telomere length measurement were critical for the clini...
Source: Human Genetics - Category: Genetics & Stem Cells Source Type: research