Polymorphisms associated with a tropical climate and root crop diet induce susceptibility to metabolic and cardiovascular diseases in Solomon Islands.

Takuro Furusawa,Ryosuke Kimura,Taro Yamauchi,Izumi Naka,Ryutaro Ohtsuka,Kazumi Natsuhara,Takafumi Ishida,Jun Ohashi,Minato Nakazawa,Ricky Eddie,Wataru Nishimura

doi:10.1371/journal.pone.0172676

Takuro Furusawa, Ryosuke Kimura + Show 9 more

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https://doi.org/10.1371/journal.pone.0172676

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Abstract

The people of the Solomon Islands represent an Austronesian (AN)-speaking population’s adaptation to a humid tropical environment and subsistence of tuberous crops. Genome-wide association studies (GWASs) of other populations (e.g. the Human Genome Diversity Project [HGDP]) have suggested the existence of genotypes adaptive to ecoregion, diet, and subsistence, and that those genotypes are also associated with metabolic and cardiovascular diseases. Recently, the incidence of non-communicable diseases has been increasing in the Solomon Islands. In the present study, we explored the association of genotypes adaptive to a tropical environment and tuberous crop diet with metabolic and cardiovascular conditions in rural and urban AN-speaking Melanesian and Micronesian populations of the Solomon Islands. A total of 561 participants were genotyped for single nucleotide polymorphisms (SNPs) potentially associated with a tropical environment (rs174570 and rs2237892) and a tuberous crop diet (rs162036, rs185819, and rs2722425). The results showed that the allele frequencies of the Solomon Islands populations adopted patterns similar to those in populations from other hot, tropical areas with a tuberous crop diet in previous studies. Furthermore, rs162036, rs185819, rs2237892, and rs2722425 were all strongly associated with one or more metabolic and cardiovascular conditions. The derived allele of rs2722425 (i.e. rs2722425-G) was significantly associated with an elevated LDL level (P = 0.000264) even after the significance level was adjusted for multiple testing (i.e., α = 0.0005). Our results suggest that the inhabitants of the Solomon Islands exhibit the effects of the tropical environment and tuberous crop diet on their allele frequencies, and that their susceptibility to metabolic and cardiovascular diseases is therefore considered to be associated with their environment and diet.

Highlights

Located in Melanesia, the Solomon Islands is a country with a humid tropical climate
When the proportions of the derived alleles were compared among populations, the proportion of G carriers of rs162036 was higher in the Solomon Islands populations than in the populations of Asia (East, Southeast, and South Asia), the Middle East, and Europe, which are less dependent on root vegetable crops than Pacific Islanders
The proportion of the derived allele (T) of rs174570 in the Solomon Islands populations was as high as in other humid tropical regions, such as Southeast Asia and Latin America, this allele was rare in tropical Africa

Summary

Introduction

Located in Melanesia, the Solomon Islands is a country with a humid tropical climate. There is still debate on the origin and migration route of the Pacific Island people [2,3,4], linguistic, archaeological, and genetic studies have suggested that the Austronesian (AN)-speaking populations originated from East Asia (or Southeast Asia in some studies), passed through the islands by voyaging, and arrived in Melanesia about 1500 years BCE, around the Gilbert Islands of Micronesia 500 years BCE, and in Polynesia by 1000 years CE [5]. The majority of the people in New Guinea and the nearby islands are Non-Austronesian (NAN)-speaking and descendants of the first human populations who settled in this region but did not migrate further, likely because they had not yet developed the technology required for long voyaging. The Solomon Islands consists of AN-speaking Melanesians (as the majority), NANspeaking Melanesians, AN-speaking Polynesian outliers, immigrant AN-speaking Micronesians, and others

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