DPY-30 is a 99 amino acid nuclear protein that is a component of MLL-containing complexes, including the ASCOM, MLL, MLL2/MLL3 and MLL3/MLL4 complexes. The gene that encodes DPY-30 maps to human chromosome 2, which is the second largest human chromosome, consisting of 237 million bases encoding over 1,400 genes. A number of genetic diseases are linked to genes on chromosome 2. Harlequin icthyosis, a rare and morbid skin deformity, is associated with mutations in the ABCA12 gene. The lipid metabolic disorder sitosterolemia is associated with ABCG5 and ABCG8. An extremely rare recessive genetic disorder, Alstr syndrome is due to mutations in the ALMS1 gene.