How is Anderson's Disease Diagnosed?
How is Anderson's Disease Diagnosed?
Below mentioned are the ways to diagnose anderson’s disease:
The diagnosis of Anderson's disease or chylomicron retention disease is frequently delayed because of their nonspecific signs and symptoms. Genetic testing is most widely used to identify the change in the chromosome, gene, or protein that is associated with chylomicron retention disease. The consequences of a genetic test can confirm the suspected genetic condition or help to determine a person’s chance of developing or passing on a genetic disorder.
Recently, the SAR1B gene was identified as responsible for Anderson's disease or chylomicron retention disease. Genomic DNA isolation from whole blood of affected person and sequencing of all the exons of the SAR1B genes, including the intron-exon boundaries can reveal the SAR1B mutation. Genotyping makes it possible to identify mutated gene SAR1A/SAR1B which causing Anderson's disease or chylomicron retention disease.
Duodenal biopsies may help in determining the expression of SAR1A proteins. The total amount of SAR1 proteins in the intestine predicts Anderson's disease or chylomicron retention disease in patients as compared to normal individuals. Certain immunohistochemical studies of the intestinal biopsies support the identification of SAR1A protein. The localization of Sar1 proteins in duodenal biopsies can be assessed by immunostaining with nova red using a chicken polyclonal antibody against recombinant human SAR1A protein and anti-chicken horseradish peroxidase-conjugated antibody.
Parental lipid screening could possibly clarify the diagnosis. Lipid profile evaluation such as total cholesterol and triglyceride concentrations; RBC analysis (acanthocytosis-theory appearance of cells), liver enzyme analysis (ALT, AST, & bilirubin), liposoluble vitamins ratios, and plasma fatty acids levels are some of the routine biochemical assays support the diagnosis of Anderson's disease or chylomicron retention disease. The unspecific decrease of vitamin E and K denotes the most severe form of this condition. Vitamin K deficiency can be further confirmed by coagulation test.
Anthropometry is described as the scientific study of the measurements and proportions of the human body. In case of chylomicron retention disease, the affected person shows failure to thrive in early infancy (within 10 months) or childhood (less than 3 years). Some symptoms may help in diagnosis, which includes chronic malabsorptive diarrhea in early infancy, frequent vomiting and abdominal distension in early infancy and neurology complication such as areflexia, decrease in deep proprioception, and ataxia is uncommon during childhood. Consanguineous marriage (blood relation) is frequent in patients with the disorder. An absence of hypocholesterolemia in both parents favors CRD.
Endoscopy can reveal the abnormal duodenum content i.e. white deposition of lipid droplets in the villi. It may due to enterocytes which are unacceptably distended by the lipid deposition. Electron microscopy analysis can reveal the aggregation of chylomicrons in the duodenum biopsy.
The diagnosis is sometimes delayed (may take months) because the symptoms are non-specific. The diagnosis is based on a history of chronic diarrhea with fat malabsorption and abnormal lipid profile. Upper endoscopy and histology reveal fat-laden enterocytes whereas vitamin E deficiency is invariably present. Creatine kinase is usually elevated and hepatic steatosis is common. Genotyping identifies the Sar1b gene mutation.
The following features assist in the proper diagnosis of Anderson's disease or chylomicron retention disease in patients. They are
- Chronic diarrhea in young infants (less than 6 months).
- Decreased total cholesterol, LDL- cholesterol, and HDL- cholesterol
- Failure to thrive
- White duodenal mucosa
- Genetic mutation of SAR1B.