The same symbol, 'iav¹', has been used for two independently isolated alleles of the 'iav, inactive' gene (CG4536), resulting in some confusion in the literature, Stock Centers and FlyBase. The two separate alleles are the EMS-induced allele of the 'hypoB' complementation group (subsequently shown to be allelic to the iav gene) described as hypoB¹ in Homyk and Sheppard, 1977, Genetics 87: 95--104 (FBrf0030192) and the allele isolated by W.D. Kaplan which was described as 'iav: inactive' in a 'New mutants report' in Kaplan, 1977, D. I. S. 52: 1 (FBrf0063568).

The Kyoto Stock Center has an iav stock (stock number 101174) which has been referred to as 'iav¹'. The notes associated with the Kyoto stock report for this allele indicate that it was originally from the Umea Stock Center (number 27741) and had the original comment 'Sierra Leone background, synonym hypoB¹', indicating that it corresponds to the Homyk and Sheppard hypoB¹ allele.

Correspondence with the Bloomington Stock Center established that they previously had a stock (number 6029) which was also referred to as 'iav¹' and which also originated from the Umea Stock Center (number 23755), with the comment 'Synonym hypoB¹'. Thus this stock also corresponded to the Homyk and Sheppard hypoB¹ allele.

Several papers describe using an 'iav¹' allele obtained from P. Salvaterra, Beckman Research Institute of the City of Hope. Correspondence with P. Salvaterra established that the iav line he had was the one isolated by W.D. Kaplan, indicating that papers using an 'iav¹' allele from P. Salvaterra have used the iav allele described in Kaplan, 1977, D. I. S. 52: 1 (FBrf0063568).

To try to minimise the potential for future confusion, 'iav¹' is no longer a valid symbol for either allele in FlyBase:

The 'hypoB¹' allele is named 'iav^hypoB-1', while the allele described in Kaplan, 1977, D. I. S. 52: 1 is named 'iav^K1'.