For instance, the sodium channel 1 subgroup (SCN1B) is located on the 19th chromosome, while the 1 subgroup (SCN1A) resides on the 2nd chromosome; both have been identified as defective in cases of generalized epilepsy associated with febrile convulsions. Here, SCN1B is linked to Febrile seizure (within the age range of 3 months to 6 years).