PTPN2 and type 1 diabetes mellitus: A single case of CVID has been attributed to the combination of a rare stop-gain and common hypomorphic variant in trans in PTPN2; the stop-gain mutation was seen in the patient's mother, in whom it appeared to cause a complex autoimmune phenotype featuring insulin-dependent diabetes, SLE, hypothyroidism, and neutropaenia, whilst the hypomorphic variant appeared in the patient's brother, who suffered from severe allergic nasal polyposis [156].