Polymerase ε1 mutation in a human syndrome with facial dysmorphism, immunodeficiency, livedo, and short stature (“FILS syndrome”)

Abstract

Homozygous missense mutations in POLE1 caused an inherited disorder characterized by facial dysmorphism, immunodeficiency, livedo, and short stature.

Abstract

DNA polymerase ε (Polε) is a large, four-subunit polymerase that is conserved throughout the eukaryotes. Its primary function is to synthesize DNA at the leading strand during replication. It is also involved in a wide variety of fundamental cellular processes, including cell cycle progression and DNA repair/recombination. Here, we report that a homozygous single base pair substitution in POLE1 ( polymerase ε 1), encoding the catalytic subunit of Polε, caused facial dysmorphism, immunodeficiency, livedo, and short stature (“FILS syndrome”) in a large, consanguineous family. The mutation resulted in alternative splicing in the conserved region of intron 34, which strongly decreased protein expression of Polε1 and also to a lesser extent the Polε2 subunit. We observed impairment in proliferation and G1- to S-phase progression in patients’ T lymphocytes. Polε1 depletion also impaired G1- to S-phase progression in B lymphocytes, chondrocytes, and osteoblasts. Our results evidence the developmental impact of a Polε catalytic subunit deficiency in humans and its causal relationship with a newly recognized, inherited disorder.