Crigler-Najjar syndrome type I (CN-I) is a rare and severe metabolic disorder. A recurrent mutation - c.1070A>G in exon 3 - was identified in the Tunisian population, suggesting a founder effect. In 2004, the detection of this mutation in two Kuwaiti Bedouin families has called the Tunisian founder effect in question again. To determine the origin of this mutation, 21 Tunisian and 2 Kuwaiti Bedouin CN-I patients were screened using nine genetic markers. Haplotype analysis confirmed the founder effect hypothesis and dated the appearance of this mutation some 32 generations ago in the Tunisian population. Using the same genetic analysis, the ancestor haplotype was identified in these two families. This result genetically confirms the blending of the Bedouin nomads within today's Tunisian population. After population migration from east to west, this mutation was introduced into the Tunisian population, and then perpetuated, probably because of marriages in isolated communities.