ATP8B1, ABCB11, and ABCB4 Genes Defects: Novel Mutations Associated with Cholestasis with Different Phenotypes and Outcomes.

OBJECTIVES: To characterize the clinical, laboratory, histologic, molecular features, and outcome of gene-confirmed progressive familial intrahepatic cholestasis (PFIC) 1-3 among Arabs and to evaluate for "genotype-phenotype" correlations. STUDY DESIGN: We retrospectively reviewed charts of 65 children (ATP8B1 defect = 5, ABCB11 = 35, ABCB4 = 25) who presented between 2008 and 2019 with cholestasis. The clinical phenotype of a disease was categorized based on response of cholestasis and itching to ursodeoxycholic acid and ultimate outcome, into mild (complete response), intermediate (partial response, nonprogressive), and severe (progression to end-stage liver disease). RESULTS: Overall, 27 different mutations were identified (ATP8B1, n = 5; ABCB11, n = 11; ABCB4, n = 11), comprising 10 novel ones. Six patients with heterozygous missense mutations (ATP8B1, n = 2; ABCB11, n = 4) had transient cholestasis. Of the remaining 3 patients with PFIC1, 2 developed severe phenotype (splicing and frameshift mutations). Of the remaining 31 patients with PFIC2, 25 developed severe disease (15 due to frameshift and splicing mutations). Of 25 patients with PFIC3, 10 developed a severe phenotype (1 splicing and 3 frameshift mutations; 6 missense). Patients with PFIC2 had significantly shorter survival time and more rapid disease progression than patients with PFIC3 (P < .001). Patients with frameshift mutations in ABCB11 gene (p.Thr127Hisfs∗6) and ABCB4 gene (p.Phe210Serfs∗5) had significantly shorter survival time than missense mutations (P = .011; P = .0039, respectively). CONCLUSIONS: We identified genotype-phenotype correlations among mutations in ABCB11 and ABCB4 genes, which underscore the prognostic value of early genetic diagnosis. The disease course in patients with PFIC3 could be favorably modified by ursodeoxycholic acid therapy.

Liver Failure Among Young Saudi Infants: Etiology, Clinical Presentation, and Outcome.

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.

Exome sequencing in routine diagnostics: a generic test for 254 patients with primary immunodeficiencies.

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.

Bile Acid Synthesis Disorders in Arabs: A 10-year Screening Study.

OBJECTIVES: Early diagnosis of bile acid synthesis disorders (BASDs) is important because, untreated, these conditions can be fatal. Our objectives were to screen children with cholestasis or unexplained liver disease for BASD and in those with confirmed BASD to evaluate the effectiveness of cholic acid therapy. METHODS: A routine serum total bile acid measurement was performed on children with cholestasis, liver cirrhosis, and liver failure. Patients were screened for BASD by fast atom bombardment ionization-mass spectrometry (FAB-MS) analysis of urine, and molecular analysis confirmed diagnosis. Treatment response to oral cholic acid (10-15 mg/kg bw/day) was assessed from liver function tests and fat-soluble vitamin levels. FAB-MS analysis of urine was used to monitor compliance and biochemical response. RESULTS: Between 2007 and 2016, 626 patients were evaluated; 450 with infantile cholestasis. Fifteen cases of BASD were diagnosed: 12 presented with infantile cholestasis (2.7%, 7 boys), an 8-year-old boy presented with cirrhosis, and two 18-month-old boys presented with hepatomegaly and rickets. Eleven were caused by 3ß-hydroxy-Δ-C27-steroid oxidoreductase dehydrogenase deficiency, 3 from Δ-3-oxosteroid 5ß-reductase deficiency, and 1 had Zellweger spectrum disorder. In all but 1, serum total bile acids were normal or low. With cholic acid therapy, 10 are alive and healthy with their native liver. Liver failure developed in 3 infants despite therapy; 2 died and 1 underwent liver transplantation. CONCLUSIONS: 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.

Gastric heterotopia of rectum in a child: a mimicker of solitary rectal ulcer syndrome.

Bleeding per rectum is an uncommon presentation in pediatric patients. Heterotopic gastric mucosa in the rectum is a rare cause of rectal bleeding. Here, we report a 3-year-old child with a bleeding rectal ulcer that was initially diagnosed and managed as a solitary rectal ulcer syndrome. After 1 month, the patient persisted to have intermittent rectal bleed and severe anal pain. Repeat colonoscopy showed the worsening of the rectal ulcer in size. Pediatric surgeon excised the ulcer, and histopathological examination revealed a gastric fundic-type mucosa consistent with the diagnosis of gastric heterotopia of the rectum. Over the following 18 months, our patient had experienced no rectal bleeding and remained entirely asymptomatic. In conclusion, heterotopic gastric mucosa of the rectum should be considered in the differential diagnosis of a bleeding rectal ulcer.

Clinical and molecular characteristics of mitochondrial DNA depletion syndrome associated with neonatal cholestasis and liver failure.

OBJECTIVE: To determine the frequency of mitochondrial DNA depletion syndrome (MDS) in infants with cholestasis and liver failure and to further clarify the clinical, biochemical, radiologic, histopathologic, and molecular features associated with MDS due to deoxyguanosine kinase (DGUOK) and MPV17 gene mutations. STUDY DESIGN: We studied 20 infants with suspected hepatocerebral MDS referred to our tertiary care center between 2007 and 2013. Genomic DNA was isolated from blood leukocytes, liver, and/or skeletal muscle samples by standard methods. Mitochondrial DNA copy number relative to nuclear DNA levels was determined in muscle and/or liver DNA using real-time quantitative polymerase chain reaction and compared with age-matched controls. Nuclear candidate genes, including polymerase γ, MPV17, and DGUOK were sequenced using standard analyses. RESULTS: We identified pathogenic MPV17 and DGUOK mutations in 11 infants (6 females) representing 2.5% of the 450 cases of infantile cholestasis and 22% of the 50 cases of infantile liver failure referred to our center during the study period. All of the 11 patients manifested cholestasis that was followed by a rapidly progressive liver failure and death before 2 years of life. Mitochondrial DNA depletion was demonstrated in liver or muscle for 8 out of the 11 cases where tissue was available. Seven patients had mutations in the MPV17 gene (3 novel mutations), 4 patients had DGUOK mutations (of which 2 were novel mutations). CONCLUSION: Mutations in the MPV17 and DGUOK genes are present in a significant percentage of infants with liver failure and are associated with poor prognosis.