Community based countrywide analysis of lactase persistence related genetic variants and their correlation with digestive symptoms in Libya.

Lactose intolerance is a complex symptomatic response to lactose maldigestion that is influenced by, but not strictly determined by, the down- regulation of the enzyme lactase. Several nucleotide polymorphisms - 13910C > T (rs4988235), - 13907C > G (rs41525747), - 13915T > G (rs41380347), - 14010G > C (rs145946881) and -14009T > G (rs869051967) upstream of the LCT gene have been associated with lactase persistence in European, African and Middle Eastern populations. We aimed to study the prevalence of lactase-persistence associated variants of the LCT gene in the Libyan population and its correlation with digestive symptoms (heartburn, diarrhea, nausea, bloating, abdominal cramps,).Buccal DNA swabs were collected from 242 adult individuals from the western, southern and eastern regions of Libya. A 500 bp DNA region spanning the - 13910C > T variant was analyzed. Novel variants (-13883T > A, -13921A > C, -13961T > C and -13962C > A) were detected in the analyzed region in addition to the previously described - 13910C > T and -13915T > G variants. However, their functional impact on lactase expression remains to be determined. The prevalence of the lactase persistence phenotype was associated with the derived alleles -13910*T and -13915*G, which were collectively detected in 30% of the study participants. The allele frequency of the lactase persistence -13915*G variant was 0.133 (SD ± 0.016), whereas the frequency of the -13910*T allele was 0.029 (SD ± 0.008). The most common was the Arab variant - 13915T > G in the eastern region of Libya followed by the European - 13910C > T variant. Both novel and well-known variants of LCT gene associated with lactase persistence are common in Libyans. Further studies are needed to confirm the association of the novel discovered variants with lactase persistence.