Age-related macular degeneration. Clinical features in a large family and linkage to chromosome 1q.

OBJECTIVES

To identify the chromosomal location of a disease-causing gene and to describe the clinical characteristics of a large family with age-related macular degeneration (ARMD).

METHODS

An ARMD pedigree was identified, and the disease state of family members was documented by stereoscopic fundus photography and was classified using a modified version of the Wisconsin Age-Related Maculopathy Grading System. A genome-wide screen at approximately 6-centimorgan spacing using a DNA-pooling strategy combined with shared-segment analysis was used to identify likely chromosomal regions. The entire family was then screened at each likely locus, and 1 positive locus was refined by screening with markers at an average density of 0.5 centimorgan and subjected to parametric linkage analysis.

RESULTS

In the 10 affected family members, ARMD was manifest by the presence of large, soft, confluent drusen accompanied by varying degrees of retinal pigment epithelial degeneration and/or geographic atrophy. Age-related macular degeneration segregated as an autosomal-dominant trait, with the disease locus mapping to chromosome 1q25-q31 between markers D1S466 and D1S413, with a multipoint lod score of 3.00.

CONCLUSION

Age-related macular degeneration localized to chromosome 1q25-q31 (gene symbol, ARMD1) as a dominant trait in a large family with a predominantly dry phenotype.

CLINICAL RELEVANCE

Identification of ARMD genes will facilitate early diagnosis and aid in understanding the molecular pathophysiological mechanisms of ARMD. This knowledge will contribute to the development of preventive and improved treatment strategies.