Cytochrome b₅ deficiency

Cytochrome b₅ deficiency is a rare condition and form of isolated 17,20-lyase deficiency caused by deficiency in cytochrome b₅, a small hemoprotein that acts as an allosteric factor to facilitate the interaction of CYP17A1 (17α-hydroxylase/17,20-lyase) with P450 oxidoreductase (POR), thereby allowing for the 17,20-lyase activity of CYP17A1.[1][2][3] The condition affects both adrenal and gonadal androgen biosynthesis and results in male pseudohermaphroditism.[1] The principal biological role of cytochrome b₅ is reduction of methemoglobin, so cytochrome b₅ deficiency can also result in elevated methemoglobin levels and/or methemoglobinemia, similarly to deficiency of cytochrome b₅ reductase (methemoglobin reductase).[1]

Cytochrome b5 deficiency
Specialty	Endocrinology

References

1. Mark A. Sperling (10 April 2014). Pediatric Endocrinology E-Book. Elsevier Health Sciences. pp. 498–. ISBN 978-1-4557-5973-6.
2. Mansouri A, Lurie AA (January 1993). "Concise review: methemoglobinemia". Am. J. Hematol. 42 (1): 7–12. doi:10.1002/ajh.2830420104. PMID 8416301. S2CID 221426714.
3. "Congenital methemoglobinemia with cytochrome b5 deficiency". N. Engl. J. Med. 315 (14): 893–4. October 1986. doi:10.1056/NEJM198610023151415. PMID 3748110.

External links

• Online Mendelian Inheritance in Man (OMIM): 250790 – Methemoglobinemia due to deficiency of cytochrome b₅