Hipobetalipoproteinemia primária: relato de caso / Primary Hypobetalipoproteinemia: a case report

Descrevemos o caso de uma paciente de 19 anos diagnosticada com hipobetalipoproteinemia primária. A paciente apresentava sintomas compatíveis com a doença como diarreia desde o primeiro mês de vida, défice de crescimento e retinopatia. A biópsia duodenal evidenciou presença de vacúolos lipídicos intraepiteliais, os quais foram altamente sugestivos para o diagnóstico. Os exames complementares evidenciaram disfunção hepática, baixos níveis séricos de triglicerídeos, e de colesterol total e frações. Após a dosagem de apolipoproteína B abaixo dos valores da normalidade, aliada a clínica e exames complementares, o diagnóstico foi realizado. A relativa escassez de dados na literatura em nosso meio, atrelada à raridade da doença, ilustra a relevância deste relato de caso, somado à importância do diagnóstico precoce

The case of a 19-year-old female patient who was diagnosed with Primary Hypobetalipoproteinemia (HBL) is described.The patient presented symptoms that were consistent with the disease, such as diarrhea from the very first month of life, growth failure and retinopathy. The duodenal biopsy showed the presence of intraepithelial lipid vacuoles that were highly suggestive of the diagnosis. Further tests showed liver dysfunction, low serum levels of triglycerides and total cholesterol and fractions. After the dosage of Apolipoprotein B below normal values, and clinical exam along with laboratory tests, the diagnosis was made. The lack of data in the literature and the rarity of the disease illustrate the importance of this case report,and of an early diagnosis.

Update on primary hypobetalipoproteinemia.

"Primary hypobetalipoproteinemia" refers to an eclectic group of inherited lipoprotein disorders characterized by low concentrations of or absence of low-density lipoprotein cholesterol and apolipoprotein B in plasma. Abetalipoproteinemia and homozygous familial hypobetalipoproteinemia, although caused by mutations in different genes, are clinically indistinguishable. A framework for the clinical follow-up and management of these two disorders has been proposed recently, focusing on monitoring of growth in children and preventing complications by providing specialized dietary advice and fat-soluble vitamin therapeutic regimens. Other recent publications on familial combined hypolipidemia suggest that although a reduction of angiopoietin-like 3 activity may improve insulin sensitivity, complete deficiency also reduces serum cholesterol efflux capacity and increases the risk of early vascular atherosclerotic changes, despite low low-density lipoprotein cholesterol levels. Specialist laboratories offer exon-by-exon sequence analysis for the molecular diagnosis of primary hypobetalipoproteinemia. In the future, massively parallel sequencing of panels of genes involved in dyslipidemia may play a greater role in the diagnosis of these conditions.

Hypocholesterolemia.

Hypocholesterolemia is defined as total cholesterol (TC) and low density cholesterol (LDL-C) levels below the 5(th) percentile of the general population adjusted for age, gender and race. Hypocholesterolemia may be attributed to inherited disorders or several secondary causes. Inherited forms of hypocholesterolemia consist of a group of rare diseases. The best studied are familial hypobetalipoproteinemia (FHBL) and abetalipoproteinemia (ABL). Clinical diagnosis rests on lipid levels and the pattern of inheritance after secondary causes are excluded. Patients with primary hypobetalipoproteinemias may manifest a variety of symptoms and signs affecting several organs (steatorrhea, neurological and ophalmological symptoms, non-alcoholic fatty liver disease) or be asymptomatic. Understanding hypocholesterolemia and the underlying molecular basis is of crucial importance since this may provide new insights in the treatment of hypercholesterolemia and cardiovascular disease.

[Clinical studies of pediatric malabsorption syndromes].

Multiple cases with various types of pediatric malabsorption syndromes were evaluated. The clinical manifestations, laboratory findings, pathophysiology, and histopathological descriptions of each patient were analyzed in an effort to clear the pathogenesis of the malabsorption syndromes and the treatments were undertaken. The cases studied, included one patient with cystic fibrosis, two with lactose intolerance with lactosuria (Durand type), one with primary intestinal lymphangiectasia, two with familial hypobetalipoproteinemia, one with Hartnup disease, one with congenital chroride diarrhea, one with acrodermatitis enteropathica, one with intestinal nodular lymphoid hyperplasia (NLH), five with intractable diarrhea of early infancy and four with glycogenosis type Ia. Each case description and outcome is described below: 1. A 15-year-old Japanese boy with cystic fibrosis presented with severe symptoms, including pancreatic insufficiency, bronchiectasis, pneumothorax and hemoptysis. His prognosis was poor. Analysis of the CFTR genes of this patient revealed a homozygous large deletion from intron 16 to 17b. 2. In the sibling case of Durand type lactose intolerance, the subjects'disaccaridase activity of the small bowel, including lactase, were within normal limits. The results of per oral and per intraduodenal lactose tolerance tests confirmed lactosuria in both. These observations suggested, not only an abnormal gastric condition, but also duodenal and intestinal mucosal abnormal permeability of lactose. 3. In the case of primary intestinal lymphangiectasia, the subject had a lymphedematous right arm and hand, a grossly coarsened mucosal pattern of the upper gastrointestinal tract (identified via radiologic examination) and the presence of lymphangiectasia (confirmed via duodenal mucosal biopsy). The major laboratory findings were hypoalbuminemia, decreased immunoglobulin levels and lymphopenia resulting from loss of lymph fluid and protein into the gastro-intestinal tract. 4. In two cases of heterozygous familial hypobetalipoproteinemia, serum total cholesterol and betalipoprotein levels were very low. The subjects presented with symptoms and signs of acanthocytosis and fat malabsorption. Further, one subject had neurological abnormalities such as mental retardation and severe convulsions. Treatment with MCT formula diet corrected the lipid malabsorption. 5. A 5-year-old girl presented with pellagra-like rashes, mental retardation and cerebellar ataxia. An oral tryptophan (Trp) and dipeptide (Trp-Phe) loading test were conducted and the renal clearance of amino acids was also evaluated in this patient and in controls. Following the oral Trp loading test, plasma levels of Trp indicated a lower peak in the case, reaching a maximum at 60 minutes. On the other hand, the oral dipeptide (Trp-Phe) loading test in the Hartnup patient showed the peak Trp plasma level was the same as the control subjects. The renal clearance of neutral amino acids in this case increased to levels 5 to 35 times normal. 6. In the case of congenital chloride diarrhea, the subject had secondary lactose intolerance, dehydration, hyponatremia, hypokalemia, hypochloremia, hyperreninemia and metabolic alkalosis. The chloride content of her fecal fluid was very high. The concentrations were 89-103 mEq/l. In contrast, her urine was chloride-free. The subject's growth and development improved after treatment with lactose free formura and oral replacement of the fecal loses of water, NaCl and KCl. Unfortunately, the patient died of a small bowel intussusception. The kidney histopathological finding was juxtaglomerular hyperplasia by a necropsy. 7. In the case of acrodermatitis enteropathica, the subject had characteristic skin lesions, low serum zinc levels and ALPase activity. An oral ZnSO4 loading test and intestinal mucosal histology by a peroral biopsy were conducted. The serum zinc peak level was 2 hours after the oral ZnSO4 loading test. Infant formula alone could not maintain normal serum zinc ranges. Light microscopic studies of the intestinal villous architecture showed a normal pattern. However, ultrastructual examination of several epithelial cells revealed numerous intracellular vesicles. After zinc therapy, these changes were decreased. The lesions were postulated as the secondary result of zinc deficiency. 8. A 12-year-old girl presented with hypogammaglobulinemia, recurrent infections, chronic diarrhea and intestinal NLH. A barium meal and follow-through examination showed multiple nodules throughout the stomach and intestine. The nodules, all uniform in size, were 2 mm diameter. The barium enema did not show NLH in the colon. Mucosal biopsy of the stomach and jejunum revealed the typical histology of NLH in the lamina propria. Also, achlorhydria was present in this patient and her serum gastrin levels were very high; 315-775 pg/ml. 9. In 4 cases of intractable diarrhea in early infancy (by Avery G B), a jejunal biopsy showed shortening villi and nonspecific enterocolitis. Some patients were found with only low lactase or low lactase and sucrase levels. An electron microscope analysis of the small bowel in 2 cases showed alterations: increased pinocytosis in microvillus membranes and lysosomes by endocytosis of undigested macromolecular substances. I postulated that the stated evidence was causative of this clinical profile. 10. I frequently observed diarrhea as a clinical manifestation in glycogenosis type Ia and lipid malabsorption in one case. The light and electron photomicrographs showed intestinal absorption cells with the glycogen deposits in the inferior devision of nuclei.