Homozygous familial hypobetalipoproteinemia caused by APOB gene variations: a case report and review of literature / 中华儿科杂志

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.

Diagnostico de hipobetalipoproteinemia en un nino de 8 años? / Diagnosis of hypobetalipoproteinemia in an 8-year-old child? / Diagnostico hipobetalipoproteinemia numa crianca de 8 anos?

La hipobetalipoproteinemia familiar es un trastorno hereditario autosomico dominante que afecta a las lipoproteinas que contienen Apo B, una proteina indispensable para el transporte de los quilomicrones en el intestino y que ademas participa en la sintesis y transporte de las VLDL en el higado. La concentracion de Apo B se usa junto con otras pruebas lipidicas para establecer el riesgo individual de un paciente de desarrollar enfermedad cardiovascular. Presentacion del caso: Paciente de 8 anos, varon, que acude a la consulta de Pediatria del Hospital Universitario Virgen Macarena de Sevilla con sintomas de dolor abdominal, deposiciones blandas y diarreicas, sobrepeso y unas quebradizas. El paciente fue derivado al laboratorio para su estudio con sospecha de hipobetalipoproteinemia. Se le solicito un hemograma, frotis sanguineo, pruebas de coagulacion, bioquimica general y estudio de riesgo vascular. Los datos del estudio bioquimico descartaron la celiaquia (IgA 174 mg/dL [100- 400 mg/dL] y antitransglutaminasa 5 U/mL [< 20]). Las determinaciones incluidas en el perfil de riesgo cardiovascular (RCV) fueron: colesterol total 83 mg/dL (45 mg/dL), c-LDL 32 mg/dL (< 160 mg/dL), colesterol no HDL 35 mg/dL, c-VLDL 3 mg/dL (< 40 mg/dL), trigliceridos 28 mg/dL, Apo-A1 112 mg/dL (119-240 mg/dL), Apo B-100 25 mg/dL (40-125 mg/dL), us-PCR 1,47 mg/dL (< 3 mg/dL), Lp (a) 2 mg/dL (< 30 mg/ dL), homocisteina 5,8 µmol/L (< 15 µmol/L), vitamina A 42 µg/dL (50-200 µg/ dL), vitamina E 1051 µg/dL (50-180 µg/dL) y 25-(OH) D 48,9 ng/mL (30-54 ng/mL) en intervalos de normalidad. El HLA-27 fue negativo. Tras encontrar hallazgos bioquimicos de bajas concentraciones de lipoproteinas con Apo B, se le solicito al paciente una prueba de saliva para realizacion de estudio genetico de LipochipR para mutaciones en el gen de Apo B y PCSK9. Se concluye que el paciente presento una disminucion de la concentracion de las lipoproteinas que contienen Apo B y trigliceridos. La sintomatologia de dolor abdominal y heces pastosas apoyaron el diagnostico clinico. La inexistencia de deficit vitaminico, retraso mental, acantocitosis y demas sintomatologia asociada, hizo pensar en una herencia heterocigota, que con las herramientas disponibles no se pudo describir geneticamente ya que LipochipR no detecta positividad para este paciente para una mutacion de cambio de aminoacidos en el gen y exon de Apo 26, PCSK9-7, PCSK9-4, PCSK9-10.

Familial hypobetalipoproteinemia is a dominant autosomal inherited disorder that affects lipoproteins containing Apo B. It is an essential protein for the transport of chylomicrons in the intestine and it is involved in the synthesis and transport of VLDL in the liver. This concentration is used along with other lipid tests to establish a patient's individual risk of developing cardiovascular disease. This is the case of an 8 year-old male patient who presented at the University Hospital Virgen Macarena in Seville with symptoms of abdominal pain, loose stools and diarrhea, overweight and broken nails. The patient was referred to the laboratory for examination with suspected hypobetalipoproteinemia. He was requested a complete blood count, blood smear, coagulation, biochemistry and vascular risk study. Biochemical data discarded celiac disease (IgA 174 mg/dL [100-400 mg/dL] y antitransglutaminase antibody 5 U/mL [< 20]). Determinations were RCV's profile: Total cholesterol 83 mg/dL (45 mg/dL), c-LDL 32 mg/dL (< 160 mg/dL), non-HDL cholesterol 35 mg/dL, c-VLDL 3 mg/dL (< 40 mg/dL), triglycerides 28 mg/dL, Apo-A1 112 mg/dL (119-240 mg/dL), Apo B-100 25 mg/dL (40-125 mg/dL), us-PCR 1,47 mg/dL (< 3 mg/dL), Lp (a) 2 mg/dL (< 30 mg/dL), Homocysteine 5,8 µmol/L (< 15 µmol/L), Vitamin A 42 µg/dL (50-200 µg/dL), Vitamine E 1051 µg/dL (50-180 µg/dL) and 25-(OH) D 48,9 ng/mL (30-54 ng/mL) in normal ranges. HLA-27 Negative. After biochemical findings of low concentrations of lipoproteins with Apo B100, the patient was requested a saliva test for genetic study conducting LipochipR for mutations of Apo B and PCSK9. It can be concluded that the patient had a decreased concentration of lipoproteins containing Apo-B and triglycerides. The symptoms of abdominal pain and tarry stools supported the clinical diagnosis. The lack of vitamin deficiency, mental retardation, acanthocytosis and other associated sintomatology, made it possible to consider it an heterozygous inheritance. which could not be genetically described with the tools available since LipochipR does not detect in this patient positivity for a mutation to the amino acid change in the gene and exon 26 of Apo, Apo 26, PCSK9-7, PCSK9- 4, PCSK9-10.

Hypobetalipoproteinemia familiar e um disturbio autossomico hereditario dominante que afeta as lipoproteinas contendo Apo--B, uma proteina essencial para o transporte de quilomicrons no intestino e esta envolvido na sintese e transporte de VLDL no figado. A concentracao de Apo-B e utilizada, juntamente com outros testes lipidicos, para estabelecer o risco individual de um paciente de desenvolver doencas cardiovasculares. O caso e o de um paciente de 8 anos, do sexo masculino, que se apresenta para consulta de Pediatria do Hospital Universitario Virgen Macarena, em Sevilha, com sintomas de dor abdominal, fezes brandas e diarreia, sobrepeso e unhas quebradicas. O paciente foi derivado ao laboratorio para exame com suspeita de hypobetalipoproteinemia. Foi pedido um hemograma completo, esfregaco de sangue, coagulacao, bioquimica geral e estudo de risco vascular. Os dados do estudo bioquimico descartaram a doenca celiaca (IgA 174 mg/dL [100-400 mg/dL] e Antitrasglutaminase 5 U/mL [<20]). As determinacoes incluidas no perfil de risco cardiovascular (RCV) foram colesterol total 83 mg/dL (45 mg/dL), LDL-C 32 mg/ dL (<160 mg/dL), colesterol nao-HDL de 35 mg/dL, VLDL-C 3 mg/dL (<40 mg/dL), triglicerideos de 28 mg/dL, Apo-A1 112 mg/ dL (119-240 mg/dL), Apo B-100-25 mg/dL (40-125 mg/dL), us-PCR 1,47 mg/dL (<3 mg/dL) de Lp (a) 2 mg/dL (<30 mg/dL), homocisteina de 5,8 µmol/L (<15 µmol/L), a vitamina A 42 µg/dL (50-200 µg/dL), vitamina E 1051 µg/dL (50-180 µg/dL) e 25- (OH) D 48,9 ng/mL (30-54 ng/mL) em intervalos de normalidade. O HLA-27 foi negativo. Depois de encontrar achados bioquimicos de baixas concentracoes de lipoproteinas com apo-B, foi solicitado ao paciente um teste de saliva para estudo genetico de LipochipR para mutacoes no gene de Apo-B e PCSK9. Conclui-se que o paciente apresentou uma diminuicao na concentracao das lipoproteinas contendo Apo-B e triglicerideos. Os sintomas de dor abdominal e fezes pastosas apoiaram o diagnostico clinico. A inexistencia de deficit vitaminico, retardo mental, acantocitose e outros sintomas associados fez pensar numa heranca heterozigotica, que com as ferramentas disponiveis nao se pode descrever geneticamente ja que LipochipR nao detecta positividade para este paciente para uma mutacao de mudanca de aminoacidos no gene e exon de Apo 26, PCSK9-7, PCSK9- 4, PCSK9-10.

Persistent transaminase elevation due to heterozygous (familial) apolipoprotein B deficiency.

Homozygous apolipoprotein B deficiency can present with fatty liver and raised levels of transaminases. Subjects with heterozygous deficiency are almost always asymptomatic. We report an asymptomatic 26-year-old man with persistently raised transaminases, in whom the diagnosis of heterozygous (familial) apolipoprotein B deficiency was made on the basis of characteristic lipid profile.