Severe combined immunodeficiency: improved survival leading to detection of underlying liver disease

Background Adenosine deaminase deficiency (ADA) is an autosomal recessive disorder leading to severe combined immunodeficiency (SCID). It is characterized patho-physiologically by intracellular accumulation of toxic products affecting lymphocytes. Other organ systems are known to be affected causing non-immune abnormalities. We aimed to conduct a cross sectional study to describe liver disease in autosomal recessive ADA-SCID. Methods Single center retrospective analysis of genetically confirmed autosomal recessive ADA-SCID was performed. Liver disease was defined as ≥1.5x the gender specific upper limit of normal (ULN; 33 IU/L for males and 25 IU/L for females) alanine aminotransferase (ALT) or moderate and severe increase in liver echogenicity on ultrasound. Results The cohort included 18 patients with 11 males. The median age was 11.5 (3.5–30.0 years) and median BMI percentile was 75.5 [36.75, 89.5]. All patients received enzyme replacement therapy at the time of evaluation. Seven (38%) and five (27%) patients had gene therapy (GT) and hematopoietic stem cell transplant (HSCT) in the past. Five patients had 1.5x ALT level more than 1.5x the U. Liver echogenicity was mild in 6 (33%), moderate in 2 (11%) and severe in 2 (11%) patients. All patients had normal Fibrosis-4 Index and Non-alcoholic fatty liver disease fibrosis biomarker scores indicating absence of advanced fibrosis in our cohort. Of 5 patients who had liver biopsies, steatohepatitis was noted in 3 patients (NAS score of 3,3,4). Discussion Non-immunologic manifestations of ADA-SCID have become more apparent in recent years as survival improved. We concluded that steatosis is the most common finding noted in our ADA-SCID cohort.