ABSTRACT
Objective: To summarize the genotypes and clinical characteristics of homozygous family hypobetalipoproteinemia (Ho-FHBL) caused by apolipoprotein B (APOB) gene variations. Methods: The clinical, laboratory, genetic, and liver histology data of a boy with Ho-FHBL managed in the hepatology ward of the Children's Hospital of Fudan University in May 2021 were retrospectively analyzed. The literature was searched from China National Knowledge Infrastructure, Wanfang Data Knowledge Service Platform, China VIP database, China Biology Medicine disc and PubMed database (up to May 2022) with "familial hypobetalipoproteinemia" or "hypobetalipoproteinemias" or "hypo beta lipoproteinemia" or "hypolipoproteinemias" as the search terms. All relevant literatures were reviewed to summarize the clinical and genetic features of Ho-FHBL caused by APOB gene variations. Results: The male patient was admitted to the hospital due to abnormal liver function tests for 8 months at the age of 4 years and 6 months. Blood biochemistry showed transaminitis and abnormally low serum levels of lipids. Liver biopsy revealed fatty liver with inflammation and early cirrhosis (Brunt score was F3G2S4). Whole exome sequencing revealed two novel variants of APOB gene (c.3745C>T, p.Q1249 * from the father and c.4589_4592delinsAGGTAGGAGGTTTAACTCCTCCTACCT, p.T1530Kfs * 12 from the mother). He was diagnosed as Ho-FHBL caused by APOB gene compound heterozygous variations. Literature search retrieved 36 English literatures and 0 Chinese literature. A total of 55 (23 males and 32 females) Ho-FHBL cases, including this one, were caused by 54 APOB gene pathogenic variants (23 frameshift, 15 nonsense, 7 missense, 8 splice and 1 gross deletions). The age of the last follow-up was between 1 month and 75 years. Among them, 28 cases had lipid malabsorption, 19 cases had early dysplasia, 12 cases had no symptoms. Twenty-one patients had symptoms related to fat soluble vitamin deficiency, including 14 cases of acanthocytosis, 10 cases of neurological symptoms, and 6 cases of ocular lesions. Thirty-four patients had liver involvement, including 25 cases of elevated transaminase, 21 cases of fatty liver, 15 cases of hepatomegaly, 9 cases of liver fibrosis, 3 cases of liver cirrhosis, 1 case of hepatic hemangioma and 1 case of liver neoplastic nodule. Conclusions: The variants of APOB gene in Ho-FHBL are mainly frameshift and nonsense variations. Patients may have lipid malabsorption and (or) early dysplasia, or symptom-free. Liver involvement is common.
Subject(s)
Child , Female , Humans , Male , Child, Preschool , Infant , Abetalipoproteinemia/diagnosis , Retrospective Studies , Hypobetalipoproteinemias/diagnosis , Fatty Liver/genetics , Apolipoproteins B/genetics , LipidsABSTRACT
La abetalipoproteinemia es causada por un defecto en la síntesis de β-lipoproteínas plasmáticas, VLDL y quilomicrones. Cursa con desnutrición grave, diarrea crónica mal absortiva, polineuritis, ataxia, retinitis pigmentaria y acantocitosis. Se presenta un niño de cinco años de edad que consultó por un cuadro compatible con esta enfermedad. El diagnóstico se hizo por biopsia de intestino delgado y laboratorio. Se inició tratamiento con dieta hipograsa y triglicéridos de cadena mediana, formas hidrosolubles de vitaminas A y D, altas dosis de vitaminas E y K intramuscular y lípidos endovenosos en forma periódica para la provisión de ácidos grasos esenciales ante evidencias de deficiencia. Recibió lípidos endovenosos quincenalmente durante cinco años hasta que comenzó con reacciones de intolerancia durante las infusiones, que hubo que espaciar. La recuperación fue excelente. Hoy, a los catorceaños, es un adolescente normal, con desarrollo y tamaño corporal normales para su edad. Ante la imposibilidad de monitorear el estado nutricional (deficiencia o exceso) en ácidos grasos esenciales y vitaminas, eventualidad posible por lo atípico de la dieta, el síndrome mal absortivo y debido a los valores no dosables en plasma se obtuvieron tres biopsias de tejido adiposo. Los resultados demostraron la dependencia de las infusiones y una composición diferente del tejido adiposo, según los distintos momentos del tratamiento y en comparación con la de los adultos normales de nuestro país. Consideramos que la determinación de ácidos grasos en el tejido adiposo es una herramienta útil en el monitoreo del tratamiento de esta grave enfermedad.