Biallelic ANGPT2 loss-of-function causes severe early-onset non-immune hydrops fetalis.

Pathogenic heterozygous ANGPT2 missense variants were recently shown to cause autosomal dominant primary lymphoedema. ANGPT2 is a ligand of the TIE1-TIE2 (tyrosine kinase with immunoglobulin-like and epidermal growth factor-like domains 1 and 2) pathway. It is critical to the formation and remodelling of blood and lymphatic vessels and is involved in vessel maintenance. ANGPT2 knockout mice die from generalised lymphatic dysfunction. We show here that a homozygous pathogenic variant causes loss-of-function and results in severe early-onset hydrops fetalis. This is the first report of an autosomal recessive ANGPT2-related disorder in humans.