Background Diagnosis of primary immunodeficiencies (PIDs) is complex and cumbersome yet important for the clinical management of the disease. Exome sequencing may provide a genetic diagnosis in a significant number of patients in a single genetic test. Methods In May 2013, we implemented exome sequencing in routine diagnostics for patients suffering from PIDs. This study reports the clinical utility and diagnostic yield for a heterogeneous group of 254 consecutively referred PID patients from 249 families. For the majority of patients, the clinical diagnosis was based on clinical criteria including rare and/or unusual severe bacterial, viral, or fungal infections, sometimes accompanied by autoimmune manifestations. Functional immune defects were interpreted in the context of aberrant immune cell populations, aberrant antibody levels, or combinations of these factors. Results For 62 patients (24%), exome sequencing identified pathogenic variants in well-established PID genes. An exome-wide analysis diagnosed 10 additional patients (4%), providing diagnoses for 72 patients (28%) from 68 families altogether. The genetic diagnosis directly indicated novel treatment options for 25 patients that received a diagnosis (34%). Conclusion Exome sequencing as a first-tier test for PIDs granted a diagnosis for 28% of patients. Importantly, molecularly defined diagnoses indicated altered therapeutic options in 34% of cases. In addition, exome sequencing harbors advantages over gene panels as a truly generic test for all genetic diseases, including in silico extension of existing gene lists and re-analysis of existing data. Electronic supplementary material The online version of this article (10.1186/s13073-019-0649-3) contains supplementary material, which is available to authorized users.

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Objectives: The published data on early infantile liver failure (EILF) are scarce and limited to Caucasians. We conducted this study to describe the etiology and outcome of EILF among Arabs and identify prognostic factors. Methods: We retrospectively reviewed our database of 524 infants presenting with liver impairment from 2008 to 2018, and identified cases of EILF defined as presence of biochemical pattern of liver disease and INR ≥2 (unresponsive to vitamin K) with onset before 3 months of life. Primary outcomes included death or liver transplantation (LT) (poor outcome group) and survival with native liver (good outcome group). Results: Forty-two cases of EILF (22 girls) were identified (8%). The etiology was indeterminate in 14 (33.3%) and established in 27 (64.3%): galactosemia (7 cases, 16.6%), tyrosinemia (5, 12%), neonatal hemochromatosis (NH), and hemophagocytic lymphohistiocytosis (HLH) (4 each, 9.5%]) mitochondrial hepatopathy (3, 7%), and miscellaneous (5, 12%). LF resolved in 15 cases (35.7%), either spontaneously or in response to specific therapy, 23 (54.7%) died, and 4 underwent LT (9.5%). ROC analysis for the best cut-off value of serum total bilirubin for prediction of study outcomes was 120 μmol/L (sensitivity 81.5%, specificity 80%). Among the diagnostic groups, galactosemia and tyrosinemia predicted good outcome, whereas the idiopathic diagnosis predicted poor outcome (OR = 13). Conclusions: Similar to Western countries, galactosemia, tyrosinemia, NH, HLH, and mitochondrial hepatopathy are the main players in EILF in Saudi Arabia. Galactosemia and tyrosinemia predict good prognosis and idiopathic diagnosis predicts poor prognosis.

BASDs are rare but treatable causes of metabolic liver disease in Saudi Arabia. BASD should be considered in infants with cholestasis and low or normal serum total bile acid concentrations.