Genetic mutations causing apoliproproein C2 deficiency, which is a necessary cofactor of lipoproteinlipase, result in familial chylomicronaemia.
We don't know very much about the frequency of these mutations.
4 apolipoproteins APOE, APOC1, APOC4, and APOC2 are located in tandem in the same direction on chromosome 19 (19q13.2). APOC4 and APOC2 can produce a conjoint gene (APOC4-APOC2). The APOC2 gene has a size of about 4kb. It consists of 4 exons. Only exons 2-4 are translated.
The clinical signs of lipoprotein lipase deficiency and apolipoprotein C2 defects are identical. Biochemically a hyperlipoproteinemia type I can be considered in homozygous state. In heterozygous state there is rather a mixed hyperlipimia evident. That can be type V according to classification of Fredrickson. There are often recurrent pancreatitises seen in these patients. The skin may show xanthomas.
This apolipoprotein is a constituent of lipoproteins rich in triglyceride. This protein is an essential component for lipoproteinlipase action on triglycerides. A defect in protein has the same physiological consequences as a defect in lipoproteinlipase: the postprandial chylomikronemia is extremely prolonged.
This is much more easily to perform than direct mesurement in plasma. In combination with lipoprotein lipase testing it is even a much more reliable test for insufficient lipoprotein degradation. The patients have to be treated with a strong regiment of fett free diet.
Clinic | Method | Carrier testing |
Turnaround | 5 days | |
Specimen type | genomic DNA |
Clinic | Method | Massive parallel sequencing |
Turnaround | 25 days | |
Specimen type | genomic DNA |
Clinic | Method | Genomic sequencing of the entire coding region |
Turnaround | 25 days | |
Specimen type | genomic DNA |
Clinic | Method | Multiplex Ligation-Dependent Probe Amplification |
Turnaround | 20 days | |
Specimen type | genomic DNA |
Chylomicronemia | ||||
ABCA1 | ||||
ABCG5 | ||||
APOA5 | ||||
APOC2 | ||||
APOE | ||||
Chylomicron retention disease | ||||
SAR1B | ||||
GPIHBP1 | ||||
LCAT | ||||
LIPA | ||||
LIPC | ||||
LMF1 | ||||
LPL | ||||
SAR1B | ||||
1. |
None (2001) Genetic determinants of plasma triglycerides: impact of rare and common mutations. |
2. |
Fojo SS et al. (1989) A nonsense mutation in the apolipoprotein C-IIPadova gene in a patient with apolipoprotein C-II deficiency. |
3. |
Tuzgöl S et al. (1994) Apolipoprotein CII-Padova (Tyr37-->stop) as a cause of chylomicronaemia in an Italian kindred from Siculiana. |
4. |
Orphanet article Orphanet ID 121388 |
5. |
NCBI article NCBI 344 |
6. |
OMIM.ORG article Omim 608083 |
7. |
Wikipedia article Wikipedia EN (Apolipoprotein_C2) |