Carpenter syndrome-1 (CRPT1) is an autosomal recessive disease, caused by homozygous mutation in the RAB23 gene on chromosome 6p11 Carpenter syndrome-2 (CRPT2) is an autosomal recessive disease, caused by mutation in the MEGF8 gene and is characterized by the association between features of CRPT2 and defective lateralization. The gene discussed is RAB23; the disease is Down syndrome.