Clinical profile of anti Ku autoantibody a cohort study from a tertiary care centre in South India

Anti Ku antibodies are myositis associated antibodies (MAA) directed against Ku protein involved in DNA repair. Aim We aimed to study the clinical profile of our patients with sera positive for anti-Ku antibody.Methods Records of patients positive for anti-Ku antibody in sera by EUROLINE myositis profile- 3 in our center between 2009 and 2014 were studied. Details of demography, clinical features, laboratory parameters, imaging findings and treatment outcome were noted from electronic medical records. Data of patients positive for MAA other than anti-Ku in sera in our clinics between 2009 and 2011 were also studied for comparison. Chi-square test was used for comparisons. Results Twenty patients (14 females, mean age of 35.5 12.8 years), with anti-Ku antibody positivity and 14 (9 females, mean age of 44.0 11.1 years) with other MAA positivity were studied. The most common manifestations in anti-Ku positive patients were arthralgia (75) and proximal muscle weakness (70) followed by skin tightness in 50, skin rash (40) and interstitial lung disease (40). Half of anti-Ku patients had overlap connective tissue disease. Response to treatment was good in majority (69). Anti-Ku positive patients tend to be younger at presentation and seemed to have higher frequency of Raynauds phenomenon and proteinuria and lower occurrence of ILD as compared to patients positive for MAA other than anti-Ku.Conclusion OCTDs is the most common diagnosis associated with anti-Ku antibodies in our study. Muscle weakness, limited skin tightness and articular symptoms are the most common manifestations of this subset. These patients tend to present at younger age, have higher frequency of Raynauds phenomenon and proteinuria, while ILD seem to present less frequently in them as compared to those positive for other MAAs. Prognosis is good in majority of our anti-Ku positive patients on treatment