Once again high tech meets low tech on chromosome 6.

1 are to be congratulated on their research of the autosomal dominant Stargardt disease gene (STGD3). This study contains some extremely complex issues that require some clarification , as well as some basic and simple findings that should be emphasized. The basic issues center on gene-alogy, phenotype classification (lumping vs splitting), genotype and haplotype analysis, and statistics. Since the submission and acceptance of this article by Donoso et al, a gene defect responsible for STGD3 was identified. 2 This recent finding helps to clarify several issues relevant to Donoso et al's article and the STGD3 gene locus in general. Their study used " high tech " as well as " low tech " molecular genetic methods, but nonetheless labor-intensive genealogical methods. As was the case with my own studies of North Carolina macular dystrophy, it was the genea-logical work that eventually lead the authors to study in more detail the molecular genetics of these different families. 3-5 It was the genealogical work that made it apparent that these different autosomal dominant Stargardt families likely originated from a common founder. Indeed, the base pair (bp) (position) deletion in the ELOVL4 gene 5 also shows a common founder in 4 small families with STGD3 1. Although genealogical methods are considered low tech, these methods are critically important and are the basic underpinnings of most, if not all, molecular genetics studies. The more accurate and complete these low tech data are, the greater the likelihood that the high tech molecular genetic parts of the study will be fruitful. Obtaining an extended family history in the United States is often difficult. Unlike isolated populations such as Finland and Iceland, there is no centralized genea-logical or medical database in the United States. Most Americans are not knowledgeable about their own family history going back more than 3 generations, and Ameri-can society is highly mobile. These factors make performing genealogical studies more difficult in America. Agrarian societies, where large stable families are typical , make genealogical studies fruitful, as demonstrated in this study. Developing family cooperation and trust are critical in these studies. This study begs the question, " what happened to the STGD2 locus on chromosome 13 reported by Zhang et al 6 ? " It now seems that the chromosome 13 locus (STGD2) might be an error, and that these families actually belong to the STGD3 locus on chromosome 6. 7 In light of …