Idiopathic mesial temporal lobe epilepsy: a syndrome with complex inheritance?

Excerpt

In a recent article, Striano et al. [1] stated that familial mesial temporal lobe epilepsy was consistent with an autosomal dominant inheritance with incomplete penetrance. In fact, this pattern of inheritance was already proposed when the syndrome was recognized by Berkovic et al. [2]. Subsequently, others researchers extended the clinical spectrum of the disorder, but they still supported the same mode of genetic transmission [3, 4]. However, some observations could point against this general agreement. First, no very large pedigrees of familial mesial temporal lobe epilepsy have been reported to date [5]. In addition, 15 out of 39 pedigrees included in three of the referred series showed that all the affected members belonged to the proband’s generation [1‐3], which would be unusual for an autosomal dominant inheritance. This would explain why only isolated families with different subtypes of the disorder have, so far, been mapped [6, 7]. On the other hand, the way in which the reported patients were ascertained could have caused a selection bias and, consequently, an inappropriate conclusion about the pattern of inheritance. Cases published in the four series cited above had to have one or more affected first-degree relatives to be included in the study [1‐4]. This mode of recruitment determines that the families selected will automatically contain a high proportion of affected members [8]. However, there might be in the community other families with the same disorder, but with a single individual affected. The possibility that such families would be improperly excluded leads Ottmann to consider that the mode of inheritance of this syndrome is still uncertain [8]. …