Evaluation of Lipin 2 as a candidate gene for autosomal dominant 1 high-grade myopia

The first autosomal dominant high-grade myopia locus has been mapped to chromosome 18p11.31 between markers D18S59 and D18S1138 by haplotype analysis. Refinement of the region by transmission disequilibrium testing suggests that a candidate gene (or genes) for this locus named myopia 2 (MYP2) is likely in an interval between markers D18S63 and D18S52. Lipin 2 (LPIN2), a candidate gene for lipodystrophy, maps in proximity to this locus. Our purpose in this study was to identify mutations and polymorphisms in the LPIN2 gene in myopic patients and control subjects. Expression studies of this gene by reverse transcription-polymerase chain reaction (RT-PCR) showed that LPIN2 was ubiquitously expressed in various tissues, such as brain, kidney, lung, heart, and skeletal muscles. It was also expressed in cornea, lens, retina, optic nerve, and sclera. Direct sequencing of the LPIN2 gene revealed 11 single nucleotide polymorphisms (SNPs) in myopia and unaffected individuals. Eight of them were novel. Among the 11 SNPs detected in this study, 2 exonic variants (G2950692A and C2924436T) were synonymous and do not lead to changes in amino acid of the translated protein product. Two transversions in intron 1 (T2951033A homozygote and heterozygote, C2951049A) and one transversions in intron 7 (G2924536C homozygote and heterozygote), 5 nucleotide variants (A 2909606T, del2909343T, G2907798C, T2907425G, T2907152C) in the 3'-untranslated region (3'-UTR), and TATTAA nucleotide deletions (homozygote and heterozygote) at 2950970-5 in intron 1 were also detected. Although LPIN2 gene was excluded as a candidate for MYP2, the SNPs detected in this study will aid in future mapping and association studies involving this gene.