<prompt> Not a feature of Hartnups disease:Pellagroid skin lesionCerebellar ataxiaMental retardationPsychological disturbances  <response>: c. Mental retardationRef: Nelsons 20e p 636-642, Ghai 8e p 653-655Clinical features of Hartnup disease:Most children with Hartnup defect remain asymptomaticMajor clinical manifestation in symptomatic patient is cutaneous photosensitivity: pellagra-like rash on sun exposureSome patients may have intermittent ataxia Psychological disturbances, but mental development is usually normal. 