It has been known for nearly 100 years that there are some forms of macular degeneration that are inherited. These inherited forms may strike young children, teenagers, young adults or persons in their 30's and 40's depending on the type of macular dystrophy. In fact, Best's disease can affect children as young as 1 year of age and has been referred to as juvenile macular degeneration. Stargardt macular dystrophy is the most frequently encountered juvenile onset form of macular dystrophy and can affect children as young as 6 years of age, teenagers and persons in their 20's, 30's and 40's. Other conditions known as "dominant drusen," "cuticular drusen," and "pattern dystrophy," are also inherited and can cause visual problems very similar to age related macular degeneration. Because inherited conditions can be studied with powerful molecular techniques more easily than non-inherited ones, researchers have been applying such methods to the study of inherited forms of macular degeneration in the hope that a better understanding of these conditions will lead to a better treatment for these and the more common age related disorders. Using a technique known as chromosome linkage analysis to look for genes that cause macular degeneration, researchers study families with inherited macular degeneration. By taking blood samples and analyzing the DNA, a computer program looks for a relationship between certain markers in the DNA and the presence of the macular disease. A study which began in 1987 with over 2000 patients made 2 major discoveries in families with juvenile macular degeneration. First, the gene that causes Best's disease was mapped to the long arm of chromosome 11. Mutations in the peripherian gene were discovered on chromosome 6, which cause a type of macular disease known as pattern dystrophy. This finding was particularly surprising since mutations elsewhere in the same gene can cause a completely different disease- retinitis pigmentosa. 

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