Novel mutations in SAR1B and MTTP genes in Tunisian children with chylomicron retention disease and abetalipoproteinemia

► Three Tunisian children with severe fat malabsorption were investigated. ► They had primary hypobetalipoproteinemia of variable severity. ► One child carried a SAR1B missense mutation causing chylomicron retention disease. ► Two children affected by abetalipoproteinemia carried two MTTP intronic mutations. ► The MTTP mutations disrupt mRNA splicing leading to premature termination codons.