Sir: In the haze of speculation about possible links between BSE and Creutzfeldt-Jakob Disease (CJD) it is hard to distinguish fact from opinion. Dr Grant's argument (27 March), that very few BSE-exposed individuals will develop CJD because only those of a rare genetic constitution are susceptible, is based on conjecture. It is true that CJD may occasionally run in families. However the extremely high incidence of this disease - one in a hundred - in those unfortunate children treated with contaminated human growth hormone suggests that genetic susceptibility is either of no relevance to transmission, or if relevant is far more common than Dr Grant would have us believe.
Dr P D Lewis