Monogenic inborn errors of immunity in autoimmune disorders

To estimate the prevalence of monogenic inborn errors of immunity in patients with autoimmune diseases (AID), the study included 56 subjects (male:female ratio: 1.07) with mean age of onset of autoimmunity 7 years (4 months-46 years). 21/56 had polyautoimmunity. 5/56 patients met the JMF criteria for PID. The different AID referred were hematological (42%) > gastrointestinal (GI) (16%) > skin (14%) > endocrine (10%) > rheumatological (8%) > renal (6%) > neurological (2%). 36/56 reported recurrent infections. 27/56 were on polyimmunotherapy. 18/52 (35%) had CD19 lymphopenia, 24/52 (46%) had CD4 lymphopenia, 11/52 (21%) had CD8 lymphopenia, and 14/48 (29%) had NK lymphopenia. 21/50 (42%) had hypogammaglobinemia; 3 of whom were given rituximab. 28/56 were found to have pathogenic variants among PIRD genes. These 28 patients had 42 AID among which hematological was most common (50%) > GI (14%) = skin (14%)> endocrine (9%) > rheumatological (7%) > renal and neurological (2%). Hematological AID was the most common AID (75%) in children with PIRD. Positive predictive value (PPV) of abnormal immunological tests was 50% and sensitivity of 70%. JMF criteria had specificity of 100% in identifying PIRD and sensitivity of 17%. Polyautoimmunity had a PPV of 35% and sensitivity of 40%. 11/28 of these children were offered transplant. 8/28 were started on sirolimus, 2/28 on abatacept, and 3/28 on baricitinib/ruxolitinib after diagnosis. In conclusion, 50% of children with AID have underlying PIRD. LRBA deficiency and STAT1 GOF were the most common PIRD. Age at presentation, number of autoimmunity, routine immunological tests, and JMF criteria are not predictive of underlying PIRD. Early diagnosis with exome sequencing alters the prognosis and opens new therapeutic avenue.