D20S19, linked to low voltage EEG, benign neonatal convulsions, and Fanconi anaemia, maps to a region of enhanced recombination and is localized between CpG islands.

Recent linkage studies located genes responsible for the low voltage EEG, benign neonatal convulsions and for the Fanconi anaemia to the vicinity of the VNTR marker CMM6 (D20S19). Physical mapping experiments using pulsefield electrophoresis in the distal part of chromosome 20q were chosen as a first step towards cloning of these genes. The observed pattern of shared fragments lead to the locus order 'tel-IP20K09-RMR6-CMM6-MS214-cen', which differs from previously reported genetic linkage maps. The physical intervals between these probes are markedly shorter compared with the genetic distances. Clusters of rare cutter sites around CMM6 point to at least four closely related CpG islands.