Work in London and Southampton (Lancet1996;348:353-8) has helped to characterise children with growth failure and psychosocial deprivation who might grow well when removed from the stressful environment. These children had hyperphagia and often learning difficulties. The proposed diagnostic criteria for ‘hyperphagic short stature’ are: growth failure with height below third centile, normal body mass index, and age over 2 years, plus one of : food stealing, or gorging and vomiting, plus two of : excessive eating, excessive drinking, food hoarding, nocturnal food foraging, or seeking out food discarded or in bins. Such children had greatly improved growth hormone secretion after three weeks in hospital.

Gene therapy means introducing a viral vector into the patient’s cells and the effects of the virus are unpredictable; it could, for insistence, cause cancer. It would be better if the virus could be got rid of once it has done its job. Now research workers in Germany have developed a technique which might achieve this aim (news report, New Scientist 1996; 151 : 20). They infected mouse cells with a murine leukaemia virus which produced an enzyme, Cre-recombinase. When the virus entered the host cell DNA the enzyme caused cleavage at sites which resulted …