Mutational Analysis of the TYR and OCA2 Genes in Four Chinese Families with Oculocutaneous Albinism.
BACKGROUND
Oculocutaneous albinism (OCA) is an autosomal recessive disorder. The most common type OCA1 and OCA2 are caused by homozygous or compound heterozygous mutations in the tyrosinase gene (TYR) and OCA2 gene, respectively.


OBJECTIVE
The purpose of this study was to evaluate the molecular basis of oculocutaneous albinism in four Chinese families.


METHODS
Four non-consanguineous OCA families were included in the study. The TYR and OCA2 genes of all individuals were amplified by polymerase chain reaction (PCR), sequenced and compared with a reference database.


RESULTS
Four patients with a diagnosis of oculocutaneous albinism, presented with milky skin, white or light brown hair and nystagmus. Genetic analyses demonstrated that patient A was compound heterozygous for c.1037-7T.A, c.1037-10_11delTT and c.1114delG mutations in the TYR gene; patient B was heterozygous for c.593C>T and c.1426A>G mutations in the OCA2 gene, patients C and D were compound heterozygous mutations in the TYR gene (c.549_550delGT and c.896G>A, c.832C>T and c.985T>C, respectively). The heterozygous c.549_550delGT and c.1114delG alleles in the TYR gene were two novel mutations. Interestingly, heterozygous members in these pedigrees who carried c.1114delG mutations in the TYR gene or c.1426A>G mutations in the OCA2 gene presented with blond or brown hair and pale skin, but no ocular disorders when they were born; the skin of these patients accumulated pigment over time and with sun exposure.


CONCLUSIONS
This study expands the mutation spectrum of oculocutaneous albinism. It is the first time, to the best of our knowledge, to report that c.549_550delGT and c.1114delG mutations in the TYR gene were associated with OCA. The two mutations (c.1114delG in the TYR gene and c.1426A>G in the OCA2 gene) may be responsible for partial clinical manifestations of OCA.
Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Jinan University, Shenzhen, P. R. China.
Yun
Y
Wang
Institutes of Translational Medicine, Nanchang University, Nanchang, P. R. China.
Zhi
Z
Wang
Department of Ophthalmology, the Second People's Hospital of Zhengzhou, Zhengzhou, P. R. China.
Mengping
M
Chen
Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Jinan University, Shenzhen, P. R. China.
Ning
N
Fan
Institutes of Translational Medicine, Nanchang University, Nanchang, P. R. China.
Jie
J
Yang
Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Jinan University, Shenzhen, P. R. China.
Lu
L
Liu
Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Jinan University, Shenzhen, P. R. China.
Ying
Y
Wang
Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Jinan University, Shenzhen, P. R. China.
Xuyang
X
Liu
D016115:Albinism, Oculocutaneous / Q000201:enzymology* / Q000235:genetics*; D044466:Asian People / Q000235:genetics*; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D005190:Family; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000235:genetics*; D009154:Mutation; D010375:Pedigree; D010641:Phenotype
D026901:Membrane Transport Proteins; C489600:OCA2 protein, human; D014442:Monophenol Monooxygenase