Dichotomizing on the basis of a refractive error of −6.00 D of myopia in the most minus meridian of the right eye (RE MMM), Young et al.
8 identified a locus for fully penetrant high myopia in a large family of Chinese descent (two-point LOD score 3.90 for marker
D18S1138 at 18p11.31). Six of the other seven families described in this report were also consistent with linkage to this locus, which has since been named
MYP2. A follow-up study in Hong Kong
10 reported evidence of linkage to this locus in 5 of the 15 participating families, and an association study
11 showed that the
MYP2 locus was an important contributor to the inheritance of high myopia in an isolated community in Sardinia. A second locus
9 for fully penetrant nonsyndromic high myopia,
MYP3 on 12q, was found in a single, large, German-Italian family (two-point LOD score 3.85 for markers
D12S1706 and
D12S327 at 12q21-23). More recently, a third locus has been identified on 17q in a single large family of English-Canadian descent (two-point LOD score 3.17 for marker
D17S1604 on 17q21-22, dichotomization criterion −5.00 D RE MMM)
7 and there has been suggestive evidence for a fourth locus on 7q in a study of 23 small families in France.
6 Linkage analysis in 53 nuclear families of juvenile-onset myopes by Mutti et al.
12 found no evidence of involvement of the
MYP2 or
MYP3 loci (dichotomization criterion −0.75 D RE least minus meridian with onset before 17 years of age).