Chylomicron retention disease

Chylomicron retention disease: genetics, biochemistry, and clinical spectrum

PURPOSE OF REVIEW

Chylomicron retention disease (CRD) is an autosomic recessive disorder, in which intestinal fat malabsorption is the main cause of diverse severe manifestations. The specific molecular defect was identified in 2003 and consists of mutations in the SAR1B or SARA2 gene encoding for intracellular SAR1B GTPase protein. The aim of this review is first to provide an update of the recent biochemical, genetic and clinical findings, and second to discuss novel mechanisms related to hallmark symptoms.

RECENT FINDINGS

CRD patients present with SAR1B mutations, which disable the formation of coat protein complex II and thus blocks the transport of chylomicron cargo from the endoplasmic reticulum to the Golgi. Consequently, there is a total absence of chylomicron and apolipoprotein B-48 in the blood circulation following a fat meal, accompanied by a deficiency in liposoluble vitamins and essential fatty acids. The recent discovery of Transport and Golgi organization and Transport and Golgi organization-like proteins may explain the intriguing export of large chylomicron, exceeding coat protein complex II size. Hypocholesterolemia could be accounted for by a decrease in HDL cholesterol, likely a reflection of limited production of intestinal HDL in view of reduced ATP-binding cassette family A protein 1 and apolipoprotein A-I protein. In experimental studies, the paralog SAR1A compensates for the lack of the SAR1B GTPase protein.

SUMMARY

Molecular testing for CRD is recommended to distinguish the disease from other congenital fat malabsorptions, and to early define molecular aberrations, accelerate treatment, and prevent complications.

Chylomicron Retention Disease: a Description of a New Mutation in a Very Rare Disease

Chylomicron retention disease, also known as Anderson's disease, is a rare hereditary hypocholesterolemic disorder, recessive inherited, characterized by nonspecific symptoms as abdominal distension, steatorrhea, and vomiting associated with failure to thrive. We describe a patient with failure to thrive, chronic diarrhea and steatorrhea who the diagnosis of chylomicron retention disease was established after several months of disease progression. The genetic study confirmed a homozygosity mutation in SAR1B gene, identifying a mutation never previous described [c.83_84delTG(p.Leu28Argfs*7)]. With this case report the authors aim to highlight for this very rare cause of failure to thrive and for the importance of an attempting diagnosis, in order to start adequate management with low fat diet supplemented with fat-soluble vitamins, reverting the state of malnutrition and avoiding possible irreversible and desvantating complications.