A new biallelic polymorphism in intron 1 of the CHRNA4 gene may cause erroneous genotyping of a closely linked CA repeat marker

A new polymorphism in intron 1 of the neuronal nicotinic acetylcholine rece ptor alpha4 subunit gene (CHRNA4) was identified. It consists of a G to T s ubstitution located in the downstream flanking region of a previously repor ted CA repeat marker. This polymorphism whose frequency is about six percen t in a control population occurs near the 3' end of the reverse primer gene rally used to type the CA repeat marker. Data are presented showing that th e newly identified polymorphism causes erroneous genotyping of the CA repea t marker which can alter the results of linkage analysis for CHRNA4. The us e of a different reverse primer located 34 nt downstream of the published s equence overcame errors in genotyping and identified two novel alleles of t he CA repeat marker. Re-typing of the marker with the new proposed primer p air in a Caucasian control population of 107 unrelated individuals was also performed. (C) 2000 Academic Press.