Editor—Juvenile retinoschisis (RS, OMIM 312700) is an X linked recessive vitreoretinal disorder that variably affects visual acuity because of microcystic degeneration of the central retina.1 2 In approximately 50% of affected males, peripheral schisis may also occur. Major sight threatening complications include vitreal haemorrhages, retinal detachment, and neovascular glaucoma.3

Recently, the gene underlying RS, designatedRS1 (also calledXLRS1), was positionally cloned4 and more than 80 different mutations covering a wide mutational spectrum, including intragenic deletions, splice site, frameshift, nonsense, and missense mutations, were identified.4-7 Interestingly, missense mutations mainly cluster in exons 4 to 6 of the RS1 gene known to encode a highly conserved discoidin domain thought to be involved in cell-cell interactions on membrane surfaces.8

The high recurrence rate of some of the RS1mutations (for example, Glu72Lys in more than 34 patients from different ethnic backgrounds) suggests a significant de novo mutation rate in RS.8 In this report, we provide the first molecular evidence of a de novo RS1 mutation (Pro203Leu) in a Greek family. The Pro203Leu mutation is present in two brothers diagnosed with severe features of RS at the ages of 9 and 5 years, respectively. We show that the mother is a heterozygous carrier while neither of the maternal grandparents carry the Pro203Leu mutation. Haplotyping data from several polymorphic DNA loci flanking the RS1 gene confirm paternity and strongly suggest that the Pro203Leu mutation originated on the X chromosome of the maternal grandfather.

Two brothers were referred to one of the authors (BL) presenting with unclassified vitreoretinal degeneration in both eyes. By history, retinal detachment had been diagnosed in the right eye in the older (III.1) at the age of 9 months. At the age of 9 years, best corrected visual acuity was 20/200 in the …