Any hereditary lymphedema in which the cause of the disease is a mutation in the FLT4 gene. The disease is MONDO_0007919 (lymphatic malformation 1). Also known as: FLT4 hereditary lymphedema, LMPH1A, Milroy disease, Nonne-Milroy disease, Nonne-Milroy lymphedema, Nonne-Milroy syndrome, Nonne’s syndrome, congenital hereditary lymphedema.