A very rare congenital distal limb malformation characterized by complete bilateral syndactyly (involving all digits 1 to 5). The disease is syndactyly type 4 (Monarch Disease Ontology identifier MONDO_0008515). Also known as: LMBR1 non-syndromic syndactyly, non-syndromic syndactyly caused by mutation in LMBR1, polysyndactyly, Haas type.