Lattig M C, Gelvez N, Plaza S L, Tamayo G, Uribe J I, Salvatierra I, Bernal J E, Tamayo M L
Instituto de Genética Humana- Programa de Estudios Genéticos en Enfermedades Visuales y Auditivas, Universidad Javeriana, Bogotá, Colombia.
Genet Couns. 2008;19(4):403-12.
Providencia is a small island located in the Caribbean Ocean, northwest of Colombia with an unusually high frequency of individuals with hearing loss (5 in 1,000) is present. The hearing loss in the island was characterized as non-syndromic autosomal recessive deafness accounting for 47% (8/17) of the deaf population, Waardenburg Syndrome (deafness associated with pigmentary anomalies) for 29% (5/17), and the remaining 24% (4/17) are cases of sporadic non-syndromic deafness. For appropriate genetic counseling a complete pedigree of families with deaf individuals was constructed. The 35delG mutation in GJB2 gene, which encodes connexin 26 (Cx26), is responsible for the deafness observed in the 8 individuals with autosomal recessive non-syndromic hearing loss. The deaf individuals with Waardenburg Syndrome and the sporadic cases did not have this mutation. Therefore, we present here an atypical case of an isolated community with at least two different genetic etiologies for deafness: non-syndromic genetic deafness caused by the 35delG mutation in the GJB2 gene and deafness associated with Waardenburg Syndrome not related to GJB2. In a small and isolated population, it is feasible to assume that the deafness is caused by the same factor; however, Providencia is an atypical case. Therefore, it is extremely important to define the exact etiology of deafness in each case, since different etiologies require different genetic counseling.
普罗维登西亚是位于加勒比海、哥伦比亚西北部的一个小岛，岛上存在听力损失个体的频率异常高（每1000人中有5人）。该岛的听力损失特征为：非综合征性常染色体隐性耳聋占耳聋人群的47%（17例中有8例），瓦登伯革氏综合征（与色素异常相关的耳聋）占29%（17例中有5例），其余24%（17例中有4例）为散发性非综合征性耳聋病例。为了进行适当的遗传咨询，构建了耳聋个体家庭的完整谱系。编码连接蛋白26（Cx26）的GJB2基因中的35delG突变，是导致8例常染色体隐性非综合征性听力损失个体出现耳聋的原因。患有瓦登伯革氏综合征的耳聋个体和散发病例没有这种突变。因此，我们在此呈现一个孤立社区的非典型案例，该社区至少有两种不同的耳聋遗传病因：由GJB2基因中的35delG突变引起的非综合征性遗传性耳聋，以及与瓦登伯革氏综合征相关但与GJB2无关的耳聋。在一个小的孤立人群中，认为耳聋是由同一因素引起是可行的；然而，普罗维登西亚是一个非典型案例。因此，明确每个病例耳聋的确切病因极其重要，因为不同的病因需要不同的遗传咨询。
