Results of linkage analysis between benign infantile familial convulsions (BIFC) and two linked DNA markers, D20S19 and D20S20, in 52 members from eight BIFC pedigrees are reported from centers in Montpellier and Paris, France, and Rome and Treviso, Italy. The gene responsible for benign familial neonatal convulsions (BFNC) has been mapped to chromosome 20q in the close vicinity of these two DNA markers. Several recombinants were observed betweeen the BIFC locus and D20S19-D20S20 markers, whereas none appeared between the BFNC locus and the markers in 11 BFNC families. The gene responsible for BFNC is not implicated in BIFC. [1]

COMMENT. The authors distinguish BFNC and BIFC by clinical and genetic markers, as follows: 1) Onset of BFNC is before 3 months and BIFC, after 3 months of age; 2) Seizures, generalized in BFNC and partial in BIFC; and 3) genetic heterogeneity.

Seizure patterns cannot be used to differentiate these benign familial convulsions without documentation by ictal EEG recordings. Ictal EEGs demonstrated a seizure of right frontal onset with secondary generalization and one of right frontal onset which remained focal in a neonate with BFNC presenting with seizures at 50 hours of age, and reported from the Prince of Wales Children’s Hospital, Randwick, Australia [2]. BFNC is heterogeneous in clinical and EEG features and cannot be distinguished from BIFC on the basis of clinical seizure patterns.