Prevalence rate of different genetic forms of OCA among the various world populations has determined OCA1 as the most widespread type of loci mapped among the Caucasian patients followed by OCA2 OCA4 and OCA3 respectively3.
Genetic analysis of families with inherited OCA so far has identified seven loci and six genes including; OCA1 (TYR) OCA2 (OCA2) OCA3 (TYRP1) OCA4 (SLC45A2) OCA5 OCA6 (SLC24A5) and OCA7 (C10orf11).
Pathogenic sequence change in SLC45A2 (MIM# 606202) gene is the cause of OCA4 condition.
There are four major forms: (i) OCA1 (mutated tyrosinase (TYR) gene);  (ii) OCA2 (mutated OCA2 gene);  (iii) OCA3 (mutated tyrosinase-related protein 1 (TYRP1) gene);  and (iv) OCA4 (mutated solute carrier family 45, member 2 (SLC45A2) gene).
Mutations in the human orthologue of the mouse underwhite gene (uw) underlie a new form of oculocutaneous albinism, OCA4. Am J Hum Genet 2001;69(5):981-988.
Condition Name Gene Location Inheritance Oculocutaneous OCA1 TYR 11q14.3 AR albinism OCA2 15q12--q13 AR OCA3 TYRP1 9p23 AR OCA4
MATP 5p13.2 AR Ocular albinism OA1 GPR143 Xp22.2 XL Aniridia AN2 PAX6 11p13 AD CSNB CSNB1 NYX Xp11.4 XL CSNB CSNB2 CACNA1F Xp11.23 XL Rod monochromacy ACHM2 CNGA3 2q11.2 AR Cone dystrophy 4 COD4 PDE6C 10q23.33 AR Blue cone monochromacy COD5 OPN1L/MW Xq28 XL Optic nerve hypoplasia PAX6 11p13 AD (septo-optic dysplasia) HESX1 3p14.3 AR Corneal opacity PAX6 11p13 AD PITX2 4q25 AD FOXC1 6p25.3 AD Congenital cataract PAX6 11p13 AD Leber's congenital LCA1- Various Various AD/R amaurosis 15 Idiopathic NYS1 FRMD7 Xq26.2 XL NYS5 Xp11.4 XL NYS2 6p12 AD NYS3 7p11.2 AD 18q23 AD Figure 3 Some associations of infantile nystagmus, from Lorenz and Gampe.
9p23 lokusundaki TYRP1 (tyrosinase-related protein 1) genindeki mutasyon sonucu gorulen OCA3 (tip 3) ve 5p'deki SLC45A2 (eski adiyla MATP) geninde resesif ozellikte mutasyon sonucu gorulen OCA4
nadir okulokutanoz albinizm tipleridir.