Here , the frequency of GJB2 variants was studied in 406 and 183 apparently unrelated children from Kenya and Sudan , respectively , with mostly severe to profound non-syndromic deafness .
O O O O O B-GeneOrGeneProduct O O O O O O O O O O O O O O O O O O O O O O B-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature O