During his career he identified many major genetic mutations in storage diseases, including the mucopolysaccharidosis (MPS) types, leading to better clinical classifications and treatments. He also wrote the NHS guidelines of the management of MPSI, MPSII and MPSVI, Niemann-Pick type C disease, infantile Pompe disease and paediatric Gaucher disease. He became the UK expert on these diseases; patients came to Manchester from all over the world for a diagnosis and Wraith travelled widely, lecturing and running clinics. He developed close links with patient groups.