Familial granulomatosis with polyangiitis: three cases of this rare disorder in one Indoasian family carrying an identical HLA DPB1 allele.

The aetiology of granulomatosis with polyangiitis (GPA) remains unclear. There is likely a complex interplay between environmental triggers and genetic predisposition. Early diagnosis and treatment improve outcome in this condition with an untreated reported mortality of 90%. There are a few cases of familial GPA in the literature, but we report here the interesting and rare scenario of three members of the same Indoasian family with GPA who share an identical human leucocyte antigen (HLA) haplotype. In particular, all three members of the family share the HLADPB1 allele *04 : 01. This is the first reported Indoasian family with GPA. The HLA antigens found on genotyping our family and, in particular, HLADPB1 has been linked with GPA in previous studies. Genome-wide association studies in Anti Neutrophil Cytoplasm Antibody (ANCA) associated vasculitis (AAV) are currently in progress and should improve understanding of the genetic aspects of this disease. There may be important implications for patients with GPA and for their relatives.