Chediak-Higashi syndrome: description of a cluster in a Venezuelan-Andean isolated region.

Fourteen cases of the Chediak-Higashi syndrome found in twelve non-related families living in a defined geographical area not larger than 200 km2 of the Tachira State, Venezuela (population of around 72,000 inhabitants) were diagnosed between 1967 and 1974. The patients were pre-school or nursing age children except one eleven year old female. Six of the patients were male. All showed the same typical somatic characteristics of this syndrome. Four cases were 2 pairs of brothers. Consanguinity of the parents was seen in only two families, even though the majority of them come from the same restricted geographic zone (Pregonero). Since this anomaly is supposedly produced by a rare recessive autosomal gene, the existence of its high frequency in a small Venezuelan region may be explained through the "founder effect" in a population with a high inbreeding coefficient.