J Hum Genet (2007) 52:690–693
DOI 10.1007/s10038-007-0167-9

SHORT COMMUNICATIONOCA2*481Thr, a hypofunctional allele in pigmentation,is characteristic of northeastern Asian populations
Isao Yuasa Æ Kazuo Umetsu Æ Shinji Harihara Æ Aya Miyoshi Æ Naruya Saitou Æ
Kyung Sook Park Æ Bumbein Dashnyam Æ Feng Jin Æ Gérard Lucotte ÆPrasanta K. Chattopadhyay Æ Lotte Henke Æ Jürgen Henke

Received: 11 April 2007 / Accepted: 24 May 2007 / Published online: 14 June 2007
 The Japan Society of Human Genetics and Springer 2007

Abstract Asians as well as Europeans have light skin, forwhich no genes to date are known to be responsible. A
mutation, Ala481Thr (c.G1559A), in the oculocutaneousalbinism type II (OCA2) gene has approximately 70%
function of the wild type allele in melanogenesis. In thisstudy, the distribution of the mutation was investigated in a
total of 2,615 individuals in 20 populations from various
areas. OCA2*481Thr prevailed almost exclusively in anortheastern part of Asia. The allele frequency was highest
in Buryat (0.24) in Mongolia and showed a north–south
downward geographical gradient. These findings suggestthat OCA2*481Thr arose in a region of low ultraviolet
radiation and thereafter spread to neighboring populations.
Keywords OCA2  Pigmentation  Polymorphism 
Population study  Skin color

I. Yuasa (&)
Division of Legal Medicine, Faculty of Medicine,
Tottori University, Yonago 683-8503, Japane-mail: yuasai@grape.med.tottori-u.ac.jp
K. Umetsu
Department of Experimental and Forensic Pathology,
Faculty of Medicine, Yamagata University, Yamagata, Japan
S. Harihara
Department of Biological Sciences,
Graduate School of Science,
University of Tokyo, Tokyo, Japan
A. Miyoshi
Department of Forensic Medicine,
Fukuoka University School of Medicine, Fukuoka, Japan
N. Saitou
Division of Population Genetics,
National Institute of Genetics, Mishima, Japan

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Introduction
Skin color is a complex genetic trait that has long intrigued
biologists. Its variation among indigenous peoples isobvious and correlated with levels of ultraviolet radiation,
becoming lighter in more northerly latitudes (Jablonski andChaplin 2000). Asians as well as Europeans have lightskin, for which no genes to date are known to be responsible. Recent interest in signatures of positive selection incandidate pigmentation genes has been raised by a longrange haplotype test and an FST-based approach (Izagirre
et al. 2006; Lao et al. 2007; Myles et al. 2007). Somecandidate genes appear to have evolved independently after
the divergence of Europeans and East Asians. The OCA2
gene, showing relatively strong signatures for natural
selection, is included among the candidate genes affecting

K. S. Park
Department of Biology, Sungshin Women’s University,
Seoul, South Korea
B. Dashnyam
Institute of Biological Sciences, Mongolian Academyof Sciences, Ulaan Baator, Mongolia
F. JinInstitute of Genetics and Developmental Biology,
Chinese Academy of Sciences, Beijing, China
G. LucotteCenter of Molecular Neurogenetics, Paris, France
P. K. Chattopadhyay
Amity Institute of Forensic Sciences,
Defence Colony, New Delhi, India
L. Henke  J. Henke
Institut für Blutgruppenforschung, Cologne, Germany

J Hum Genet (2007) 52:690–693

skin lightening in East Asian populations (McEvoy et al.
2006; Norton et al. 2007).
The human OCA2 gene (GenBank GeneID: 4948;
accession numbers: NM_000275 and NT_000015), thehomologue of the murine pink-eyed dilution (p) gene,plays a role in regulating the pH of melanosomes. Somemutations in the OCA2 gene result in oculocutaneousalbinism type II (OCA2). The OCA2 gene spans 350 kb
on chromosome 15q11.2–q12 and consists of 24 exons,encoding an 838-amino acid polypeptide (Lee et al. 1995;
Oetting et al. 2005; Puri et al. 2000). A c.G1559A(Ala481Thr; unregistered in Entrez SNP) mutation inexon 14 was first discovered as a compound heterozygote
in a European–American patient with apparent autosomal
recessive ocular albinism, and its frequency was estimatedto be 0.01 in the testing of 50 unrelated normal Caucasiansubjects (Lee et al. 1994). Thereafter, this mutant allele,
OCA2*481Thr, has sporadically been observed in Japanese OCA2 patients (Saitoh et al. 2000; Kato et al. 2003;
Suzuki et al. 2003a; Kawai et al. 2005; Ito et al. 2006)
and a German patient with congenital cataract and macular hypoplasia (Graw et al. 2006). A transfection study
showed that OCA2*481Thr had approximately 70%
function of the wild type allele in melanogenesis andconfirmed it was a relatively mild OCA2 allele (Sviderskaya et al. 1997). This allele is not rare, but has been
observed at a frequency as high as 0.10 in Japanese OCA
patients and 0.12 in normally pigmented Japanese volunteers (Suzuki et al. 2003b), and it is warned that a
number of subclinical patients of OCA2 with this allele
might exist not only in Japan, but also all over the world(Kawai et al. 2005). However, as there have been only
two studies on distribution of the A481T mutation, it remains unknown whether OCA2*481Thr exists in otherpopulations. In this study, therefore, we investigated thefrequency of OCA2*481Thr in more than 2,600 people
from 20 African and Eurasian populations.

Subjects and methods
DNA samples were obtained from 2,615 unrelated individuals living in various areas of Eurasia (Table 1; Fig. 1).
The donors were selected at random, irrespective of skincolor, and their phenotypic data were unavailable. This
study was approved by the Ethical Committee at the Faculty of Medicine, Tottori University. The typing of the
A481T mutation was carried out based on the principle of
the amplified product length polymorphism (APLP)
method (Watanabe et al. 1997). The sequences of theprimers used are as follows: OCA2-481-Thr: 5¢-atatCAC
AAACATTGGAGGtGCTA-3¢ (nucleotide positions 115895-115914; lower cases are non-complementary nucle-

691

otides), OCA2-481-Ala: 5¢-CACAAACATTGGAGGAaCTG-3¢ (115895-115914) and OCA2-481-R: 5¢-TTGGAAACAATAATGACATTTGG-3¢ (115957-115935). The
PCR cocktail consisted of 100 ll of Multiple PCR MasterMix from a Multiplex PCR Kit (Qiagen), 20 ll of three
primers (1:3:1) with a concentration of 10 pmol/ll, and80 ll of water. PCR was performed in a volume of 8 ll
containing 7.5 ll of the PCR cocktail and 0.5 ll of asolution containing about 10 ng of genomic DNA. Cycle
conditions were 95C for 15 min, then 30 cycles of 94Cfor 30 s, 56C for 30 s, 72C for 30 s, and a final extension
step of 10 min at 72C. The products were separatedusing a polyacrylamide gel (9%T, 5%C), then visualized
by ethidium bromide staining. The homozygotes of
OCA2*481Thr and OCA2*481Ala showed 67 and 63-bp
bands, respectively, whereas the heterozygotes had bothbands. Allele frequencies were estimated and Hardy–
Weinberg equilibrium was tested using Arlequin program
version 3.01 (Excoffier et al. 2005).

Results and discussion
Table 1 summarizes differences in the distribution of the
A481T genotypes and allele frequency for the mutant in 20
populations. In each population, there was no statisticallysignificant departure from Hardy–Weinberg equilibrium(data not shown). The highest value of the OCA2*481Thr
frequency was observed in Buryat (0.24) and the second
highest in Khalha (0.13). The frequencies in northern Han
Chinese in Shenyang, Koreans, and Japanese were similar
to each other and ranged from 0.075 in Tottori to 0.057 in
Okinawa. These values are lower than the data (0.12) inNagoya, central Japan (Suzuki et al. 2003). A slight but
significant difference in distribution was observed between
Okinawa and Nagoya (v2 = 3.92, P < 0.05). In contrast,
other Han Chinese populations were either low or zero.
This allele was not found in Indo-European and African
populations except for Turks in Germany. A recent study
also failed to detect OCA2*481Thr in about 3,000 European descendants in Australia (Duffy et al. 2007). The
frequency (0.01) in Caucasians reported previously (Leeet al. 1994) must have been overestimated. Thus,
OCA2*481Thr is characteristic of northeastern Asian
populations.
Buryat in Mongolia showed the highest frequency, butthere may be some populations with higher frequencies innortheast China, Siberia, and/or Central Asia. Anyway,
OCA2*481Thr is nearly restricted to a northeastern part ofAsia. The distribution of OCA2*481Thr reflects the
migration of ancient northeastern Asians. This allele musthave occurred recently in a region of low ultraviolet radiation and have spread to northeast and Far East Asia. It

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692
Table 1 Distribution of A481T
Genotypes and OCA2*481Thr
frequencies

J Hum Genet (2007) 52:690–693

No.

Population

Collection
place

n

A

A/T

T

Frequency of
OCA2*481Thr

1

BuryatDashbalbar

143

79

59

5

2

KhalhaUlaan Baator

173

131

39

3

0.130

3
4

KoreanKoreanSeoul
Kwangju

139
141

120
121

19
19

0
1

0.068
0.074

5

Japanese

Yamagata

289

251

37

1

0.067

6

Japanese

Tottori

179

152

27

0

0.075

7

Japanese

Okinawa

87

78

8

1

0.057

8

Han Chinese

Shenyang

103

89

14

0

0.068

9

Han Chinese

Beijin

40

37

3

0

0.038

10

Han Chinese

Xi’an

109

101

8

0

0.037

11

Han Chinese

Wuxi

119

117

2

0

0.008

12

Han Chinese

Changsha

101

96

5

0

0.025

13

Han Chinese

Putien

118

112

6

0

0.025

14

Han Chinese

Huizhou

111

111

0

0

0.000

15

Indian

New Delhi

107

107

0

0

0.000

16

Turk

West Germany

200

195

5

0

0.013

17

GermanWest Germany

291

291

0

0

0.000

18

FrenchRheims

98

98

0

0

0.000

19
20

Nigerian
GhanaianWest Germany
West Germany

31
36

31
36

0
0

0
0

0.000
0.000

Fig. 1 Location of Asian populations analyzed in the present study

showed a north–south downward geographical gradient.
There is a significant correlation between allele frequencies
and degrees of latitude in 14 East Asian populations(r = 0.776, P < 0.01). However, the frequencies areslightly higher in Korean and Japanese than in Han Chinese. This difference in distribution reminds us of the
Y-chromosomal haplogroup C, frequencies of which differ remarkably between Han Chinese and northeast Asians
including Buryat and Mongolian populations. Koreans andJapanese have higher frequencies than Han Chinese.

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Genotypes of A481T

0.241

OCA2*481Thr has also made less contribution to the genepools of Chinese Han populations than those of Far East
populations, as haplogroup C could not expand extensively into mainland China due to the rapid and striking
northward migration and expansion of haplogroup O fromsouth China (Hammer et al. 2006; Xue et al. 2006).
OCA2*481Thr has extended from northeast Asia throughthe Korean peninsula to the Japanese archipelago. The
somewhat low frequency in Okinawa suggests a relatively
weak gene flow from Kyushu to Okinawa. An east–west
decreasing cline may also be observed in Eurasia. It isnecessary to investigate the distribution in more detail andwhether OCA2*481Thr in Europeans has the same origin
as that in Asians. These expansions may also be a result ofa certain selective advantage of hypofunction in pigmentation.
Individuals homozygous for OCA2*481Thr appear
phenotypically normal (Suzuki et al. 2003b; Ito et al.
2006). However, this allele may affect variation in skincolor in Japanese because of its hypofunction in pigmentation. Japanese skin type is classified on the basis of anindividual’s susceptibility to sunburn and ability to tan:
type I, always burns, never tans; type II, moderately burns,
moderately tans; type III, never burns, always tans (Satohand Kawada 1986). Subjects with type I showed statistically higher prevalence rates for actinic keratosis andnonmelanoma skin cancer in comparison with subjects

J Hum Genet (2007) 52:690–693

having the other types. The incidence of type I was estimated to be 18.6% in Kasai City, western Japan and 10.3%
in Ie Island, Okinawa (Naruse et al. 1997; Nagano et al.
1999). These values coincide with total values of thehomozygote and heterozygote for OCA2*481Thr in Honshu and Okinawa. Individuals with OCA2*481Thr may
have less resistance to the stress of sunburn (Kawai et al.
2005).
Recently, mutant alleles in the melanocortin 1 receptor(MC1R), the membrane-associated transporter protein(SLC45A2), and a putative cation exchanger protein(SLC24A5) have been elucidated to play a key role in lightskin and its variation in European populations (review,
Sturm 2006). In contrast, little is understood about thegenetic and molecular basis of light skin color in Asian
populations. OCA2*481Thr described here is, of course,
not a key mutation responsible for light skin pigmentationin Asians.

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