Table 2 Chylomicron Retention Disease Diagnosis

Anthropometry

Constant but unspecific failure to thrive in early infancy (1-6 months)

Digestive

Chronic malabsorptive diarrhea in early infancy, frequent vomiting and abdominal distension in early infancy

Neurology

Areflexia, ↓ deep proprioception, and ataxia are uncommon during childhood and there is no retinopathy

Lipids

In patients with a suggestive profile:

↓ HDL and N^al TG are the most discriminative specificities of CRD.

↓↓ Total cholesterol and ↓↓ LDL: intensity of decrease only around 50% normal values

Neuromuscular

↑ (1.5-4N) CK discriminative but inconstant abnormalities for CRD

Blood Cell Count

Absence of acanthocytosis in infancy is more frequent in CRD than in AB or HB

Hepatic

Frequent and early but not specific ↑ (1.5-3N) AST and/or ALT, with normal GGT, bilirubin and alkaline phosphatase

Liposoluble vitamins

Unspecific decrease ↓↓↓ E is the most severe and only permanent vitamin deficiency even with supplementation, ↓↓ A, ↓ - N^al D, ↓ - N^al K

Coagulation

↓ - N^al INR. Decreased INR if there is vitamin K deficiency

Plasma fatty acid

Abnormal profile, omega 6 linoleic acid deficiency, normal omega 3

Fasting lipids in parents

N^al

TGs are normal at baseline but do not increase postprandially and lack of change in low HDL after fat load

Unspecific white duodenal mucosa

Optic microscopy

Villi are normal but the enterocytes are grossly distended by lipid droplets

Electron microscopy

Chylomicron-like aggregates, membrane bound?

Mutations in SAR1B, Chromosome 5

1) Chronic diarrhea in young infants (< 6 Mo). Normal TG with decreased total cholesterol, LDL-C and HDL-C

2) Failure to thrive

3) White duodenal mucosa at endoscopy→ genetic hypocholesterolemia?

4) Genetic mutation of SAR1B → CRD confirmed