<prompt> A young patient present with significant loss of central vision and a normal ERG. There is no obvious family history of similar presentation. The most likely diagnosis -Bests diseaseStargardts diseaseRetinitis PigmentosaCone Rod Dystrophy  <response>: Loss of central vision along with a normal ERG is consistant with a diagnosis of Bests disease and stargardts disease. Absence of a positive family history favours a diagnosis of stargardts disease.Stargardts disease being an autosomal recessive disorder may not reveal a positive family history. Bests disease, being an autosomal dominant disorder should have a positive family history. 