Mutational analysis of oculocutaneous albinism: a compact review

Abstract

Oculocutaneous albinism (OCA) is an autosomal recessive disorder caused by either complete lack of or a reduction of melanin biosynthesis in the melanocytes. The OCA1A is the most severe type with a complete lack of melanin production throughout life, while the milder forms OCA1B, OCA2, OCA3, and OCA4 show some pigment accumulation over time. Mutations in TYR, OCA2, TYRP1, and SLC45A2 are mainly responsible for causing oculocutaneous albinism. Recently, two new genes SLC24A5 and C10orf11 are identified that are responsible to cause OCA6 and OCA7, respectively. Also a locus has been mapped to the human chromosome 4q24 region which is responsible for genetic cause of OCA5. In this paper, we summarized the clinical and molecular features of OCA genes. Further, we reviewed the screening of pathological mutations of OCA genes and its molecular mechanism of the protein upon mutation by in silico approach. We also reviewed TYR (T373K, N371Y, M370T, and P313R), OCA2 (R305W), TYRP1 (R326H and R356Q) mutations and their structural consequences at molecular level. It is observed that the pathological genetic mutations and their structural and functional significance of OCA genes will aid in development of personalized medicine for albinism patients.

Figure 1

Flow chart of OCA 1–4 gene analysis.

Figure 2

The superimposed structure of native and mutant TYR proteins and mutant residues in stick model: (a) T373K, (b) N371Y, (c) M370T, and (d) P313R.

Figure 3

(a) Snapshots of native and mutant P protein conformation at different simulation time steps [74]. (b) The superimposed structure of native and mutant (R305W) P proteins and mutant residues in a stick model.

Figure 4

Snapshots of native and mutant (R326H and R356Q) TYRP1 protein conformation at different simulation time steps [75].

Figure 5

(a) The superimposed structure of native and mutant structures (R326H and R356Q) TYRP1 proteins and mutant residues in a stick model. (b) The superimposed structure of native and mutant (Y317C) SLC45A2 proteins and mutant residue as a stick model.