The cause of<unk>  is unclear, however it is believed to be partly related to genetic factors. Genetics Genetics, based on twin studies, appear to play only a small role in<unk>  as of 2007. Genome-wide association studies (GWAS) have been used to investigate the genetic foundation of<unk> . Although no conclusive result has been shown, various candidates have been identified. In a study conducted in 2011 on various Asian populations, variants in the PDGFRA gene on chromosome 4q12 were identified to be associated with corneal<unk> . A follow-up study in 2013 on the European population, however, found no variant significantly associated with corneal<unk>  at the genome-wide level (single-nucleotide polymorphism rs7677751 at PDGFRA). Facing the inconsistency, a study by Shah and colleagues in 2018 included both populations with Asian and Northern European ancestry. They successfully replicated the previously identified genome-wide significant locus for corneal<unk>  near the PDGFRA gene, with a further success of identifying three novel candidate genes: CLDN7, ACP2, and TNFAIP8L3. Other GWAS studies also provided inconclusive results: Lopes and colleagues identified a susceptibility locus with lead single nucleotide polymorphism rs3771395 on chromosome 2p13.3 in the VAX2 gene (VAX2 plays an important role in the development of the dorsoventral axis of the eye); Li and associates, however, found no consistent or strong genetic signals for refractive<unk>  while suggesting a possibility of widespread genetic co-susceptibility for spherical and<unk> igmatic refractive errors. They also found that the TOX gene region previously identified for spherical equivalent refractive error was the second most strongly associated region. Another recent follow-up study again had identified four novel loci for corneal<unk> , with two also being novel loci for<unk> : ZC3H11B (associated with axial length), NPLOC4 (associated with myopia), LINC00340 (associated with spherical equivalent refractive error) and HERC2 (associated with eye color).
Astigmatism
Paragrammatism
Apophlegmatism
Agrammatism
Social-emotional agnosia
Boanthropy
Integrative agnosia
Visuospatial dysgnosia