Acromesomelic dysplasia Grebe type (AMDG, MIM: 200700) 112 and Demirhan type (AMDD, MIM: 609441) 113 are associated with biallelic loss of activity mutations in BMPR1B (encoding the BMP type I receptor ALK6). The gene discussed is BMPR1B; the disease is Acromesomelic dysplasia, Grebe type.