Candidate high myopia loci on chromosomes 18p and 12q do not play a major role in susceptibility to common myopia.
BACKGROUND
To determine whether previously reported loci predisposing to nonsyndromic high myopia show linkage to common myopia in pedigrees from two ethnic groups: Ashkenazi Jewish and Amish. We hypothesized that these high myopia loci might exhibit allelic heterogeneity and be responsible for moderate /mild or common myopia.


METHODS
Cycloplegic and manifest refraction were performed on 38 Jewish and 40 Amish families. Individuals with at least -1.00 D in each meridian of both eyes were classified as myopic. Genomic DNA was genotyped with 12 markers on chromosomes 12q21-23 and 18p11.3. Parametric and nonparametric linkage analyses were conducted to determine whether susceptibility alleles at these loci are important in families with less severe, clinical forms of myopia.


RESULTS
There was no strong evidence of linkage of common myopia to these candidate regions: all two-point and multipoint heterogeneity LOD scores were < 1.0 and non-parametric linkage p-values were > 0.01. However, one Amish family showed slight evidence of linkage (LOD>1.0) on 12q; another 3 Amish families each gave LOD >1.0 on 18p; and 3 Jewish families each gave LOD >1.0 on 12q.


CONCLUSIONS
Significant evidence of linkage (LOD> 3) of myopia was not found on chromosome 18p or 12q loci in these families. These results suggest that these loci do not play a major role in the causation of common myopia in our families studied.
Inherited Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, 333 Cassell Dr., Suite 2000, Baltimore, MD 21224, USA. ibayg@mail.nih.gov
Grace
G
Ibay
Betty
B
Doan
Lauren
L
Reider
Debra
D
Dana
Melissa
M
Schlifka
Heping
H
Hu
Taura
T
Holmes
Jennifer
J
O'Neill
Robert
R
Owens
Elise
E
Ciner
Joan E
JE
Bailey-Wilson
Dwight
D
Stambolian
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002881:Chromosomes, Human, Pair 12; D002887:Chromosomes, Human, Pair 18; D003198:Computer Simulation; D008040:Genetic Linkage; D020022:Genetic Predisposition to Disease; D006801:Humans; D007585:Jews / Q000235:genetics; D015233:Models, Statistical; D009216:Myopia / Q000208:ethnology / Q000235:genetics*; D010414:Pennsylvania; D018709:Statistics, Nonparametric