FLT4 and lymphedema: For example, autosomal-dominant loss-of-function FLT4 gene mutations underlie Nonne-Milroy lymphedema of the lower limbs, while homozygous and compound heterozygous mutations in the mechanically activated ion channel PIEZO1 result in an autosomal recessive form of dysplasia with a high incidence of non-immune hydrops fetalis and childhood facial and limb lymphoedema [76, 77].