A complex malformation syndrome caused by variation in the HMGB1 gene. This disorder is characterised by brachydactyly, brachyphalangy of fingers, tibia aplasia or hypoplasia, polydactyly, and contractures of large joints. Patients also present microcephaly, malformed ears, and blepharophimosis. Most patients present developmental delay, hearing impairment, and genitourinary anomalies.