The distribution of DQ genes in the Saharawi population provides only a partial explanation for the high celiac disease prevalence

Celiac disease (CD) is a multifactorial disorder of the small intestine caused by a permanent dietary intolerance to gluten. The combined presence of the HLA class II DQA1*0501 and DQB1*0201 alleles represents the major genetic component for disease predisposition. It has been shown that the Saharawi refugees living in northern Africa have a very high frequency of CD. In the present study we analysed this population to evaluate the degree of association with CD of the haplotypes and genotypes at the main HLA-DQB1 and DQA1 disease loci. We found a strong association of the DR3, DQB1*0201-DQA1*0501-positive haplotypes and genotypes. A very high frequency of DR3, DQB1*0201-DQA1*0501 was also observed in the general Saharawi population. These results indicate that there is a good correlation between disease prevalence and frequency of the main predisposing haplotype in the background population. However, the correlation is incomplete because similar frequencies of DR3 are also observed in populations such as the Sardinians showing a much lower prevalence of CD. We can conclude that the distribution of DQ genes in the Saharawi population only provides a partial explanation for the high prevalence of CD. Other factors, such as rapidly changing dietary habits and/or non-DQ genes, may also play some role.