Greater prevalence of PROKR2 mutations in Kallmann syndrome patients from the Maghreb than in European patients

Abstract

Context: Kallmann syndrome (KS) is a genetically heterogeneous developmental disorder that associates hypogonadotropic hypogonadism and anosmia. Various causative genes have been identified, but their respective involvement in different world regions is poorly documented. Objective: We aimed to compare the prevalence of mutations in five routinely analyzed KS genes between Maghrebian and European patients. Methods: Blood samples from 120 presumably unrelated Maghrebian patients were collected for DNA sequencing by the Sanger technique. The prevalence of the non-synonymous mutations in KAL1, FGFR1, FGF8, PROKR2, and PROK2 was determined for each gene, and compared with those previously obtained from the analysis of 712 European patients. Results: Diverse mutations in PROKR2, a gene involved both in monogenic recessive and digenic/oligogenic KS transmission modes, were found in 23.3% of the Maghrebian patients, but only in 5.1% of the European patients (Fisher's exact test, P<0.001), whereas mutations in each of the other four KS genes were present either at similar frequencies in the Maghrebian and European patients (KAL1, PROK2, FGF8, from 6.6 to 0.8%; Fisher's exact test, P≥0.4 for all comparisons) or at a lower frequency in Maghrebian patients (FGFR1, 5.0 vs 11.7%; Fisher's exact test, P<0.05). Homozygosity resulting from consanguineous marriages was not sufficient to account for the greater prevalence of PROKR2 mutations in the Maghrebian patients. Conclusions: The great prevalence of PROKR2 mutations in Maghrebian patients has practical consequences for molecular diagnosis of the disease and genetic counseling in the Maghrebian population. © 2013 European Society of Endocrinology.