LAUSR

Deficiency of adenosine deaminase 2 (DADA2) is a rare autosomal recessive condition first described in 2014 which is characterised by vasculitis, systemic inflammation, immunodeficiency and cytopenias. The vasculitis is difficult to differentiate from polyarteritis nodosa and typically presents with recurrent strokes. It can also affect the skin and present with livedo racemosa. Clinical presentation varies widely; from vasculitic manifestations which tend to present later in life to severe haematological abnormalities such as bone marrow failure which tend to present earlier in life. Treatment with TNF inhibitors reduces the risk of additional strokes and controls inflammation in the presence of vasculitis but is not very effective against bone marrow failure. We present the case of a 44-year-old gentleman who was being investigated for possible vasculitis by the rheumatology team in view of a history of Raynaud’s, 20-year history of recurrent leg ulcers and a previous pontine infarct. He presented acutely to the emergency department with numbness below the midthoracic level, weakness of his lower limbs and hands and urinary retention. His symptoms had progressed over a period of a few hours. On examination power was 4/5 on the MRC power scale for shoulder abduction and elbow flexion, 2/5 for elbow extension, 3/5 for wrist extension and 1/5 for finger extension. Power was 1/5 on his lower limbs. Sensation to pain was reduced with a T6 sensory level. Proprioception and vibration sense were intact. Upper limb reflexes were brisk. Knee jerks and left ankle jerk were difficult to elicit. Plantars were downgoing. Cranial nerves were normal. Bloods showed a white cell count of 6.7x109/l, haemoglobin of 96g/l (microcytic), platelets of 243x109/l, creatinine 119μmol/l (baseline 85μmol/l) and CRP of 42.9mg/l. Vitamin B12 was 200ng/l and folate levels were 2.2μg/L. ANA, ANCA, cryoglobulins and hepatitis serology were negative. MRI brain showed a 4mm area of hyper-density in the left pons. MRI whole spine was unremarkable. CSF showed normal protein, white cell count and glucose level. The patient was transferred to a tertiary neurology centre and a diagnosis of anterior spinal cord infarction was made. A nerve biopsy was performed which showed evidence of vasculitis and he was pulsed with methylprednisolone and commenced on high dose oral steroids. Genetic testing showed a pathogenic mutation in the adenosine deaminase 2 gene. He is currently awaiting to commence treatment with TNF inhibitors. We conclude that DADA2 is an important differential in a young patient with suspected vasculitis especially in the presence of infarction. Identification of DADA2 allows initiation of treatment with TNF inhibitors which reduces the risk of additional strokes. Disclosure M. Xenophontos: None. J. Gan: None. A.C. Seneviratne: None.