ELSEVIER Clinica Chimica Acta 225 (1994) 85-88 Polymorphism Letter to the editor at the glutathion~ S-transferase GSTMl locus: a study of the frequencies of the GSTMl A, B, A/B and null phenotypes in Nigerians Lei Zhao”, Julie Allderseaa, Anthony Frye?, Anthony Tighe”, Bill Ollierb, Wendy Thomsonb, Peter Jones’, Richard Strange*a zyxwvutsrqpon ‘Clinical Biochemistry Research Laboratory, Centre for Pathology and Molecular Medicine, School of Postgraduate Medicine, Keele University. North StaffordFhire Hospital, Stoke-on-Trent, ST4 7QB. Staffordshire, UK bARC Epidem~oIogy Research Unit, University of Manchester, ~~ehesfer, MZ3 9PT, UK ‘~e~rtrnen~ of Ma~hemat~es, Keele Vniversity, Stoke-on-Trent, Slaffor~hire, UK (Received 14 December 1993; accepted 15 January 1994) Key words: Glutathione S-transferase GSTMl; Phenotypes; Nigerians Dear Editor, GSTMI, a mu class gene of the human glutathione S-transferase supergene family, demonstrates pol~o~hism that arises from homo- and heterozygotic com- binations of the GSTM *o, GSTMl *A and GSTMI 23 alleles [l]. GSTMI*O is deleted and homozygotes (null phenotype) express no protein, while GSTMI *A and GSTMI*B differ by a single base in exon 7 [2]. They encode monomers that form homo- and heterodimeric enzymes. Polymorphism at GSTMI has been noted in many populations. GSTMl*O homozygosity is common, with frequencies in Chinese, Japanese, French and English ~pulations of between 43 and 58% [ 1,3-71. Reports of a lower incidence in Indians contrast with 100% penetrance in some Micronesians and suggest population differences [ 11. Other alleles also demonstrate differences; the frequency of GSTMI *A is higher and of GSTA41 *B is lower in Indians, French, English and Malays than in Japanese and Chinese [1,3-71. Interest in GSTMI has been stimulated by studies indicating that GST~l W * Corresponding author. 0009-8981/94/$07.00 0 1994 Elsevier Science B.V. All rights reserved. SSDI 0009-898 I (94)05796-U