ALAS2: There are 60 loss-of-function mutations in exons 1-11 causing X-linked sideroblastic anemia and 2 gain-of-function mutations causing XLP.

— indicates not applicable.

*Number of exons and those encoding separate housekeeping and erythroid-specific forms indicated in parentheses.

†M indicates mitochondria; and C, cytoplasm.

‡Number of known mutations from the Human Gene Mutation Database (www.hgmd.org) as of May 1, 2012.

§Crystallized from human (H), murine (M), Escherichia coli (E), Bacillus subtilis (B), Rhodobacter capsulatus (R), Pseudomonas aeruginosa (P), Shewanella amazonensis (S), Thermus thermophilus (T), Nicotiana tabacum (N), Aquifex aeolicus (A), Shigella flexneri (F), Leishmania donovani, naafi, and major (L), Desulfovibrio desulfuricans (D), Exiguobacterium sibiricum (ES), Myxococcus xanthus (X), or yeast (Y) purified enzyme; references in Protein Data Bank (www.rcsb.org).