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Table 1 Studies of cobalamin absorption, transport, cellular uptake and intracellular metabolism in a patient with a homozygous G425R mutation in ZFYVE20

From: Single point mutation in Rabenosyn-5 in a female with intractable seizures and evidence of defective endocytotic trafficking

Intrinsic Factor antibodies Negative antibodies
Parietal Cell antibodies
Gastric Intrinsic Factor Protein (GIF) No pathogenic mutations on WES (coverage × 30, last 5 exons of AMN × 3–5)
Cubilin (CUB)
Megalin (LRP2)
Amnioless (AMN)
Total Haptocorrin (TCN1) 592 pmol/L (normal 240-680)
Plasma Total Transcobalamin (TCNII)* 1520 pmol/L (normal 500-1.500)
Plasma Holotranscobalamin* 182 pmol/L (normal 40-160)
Transcobalamin Receptor related genes (TCbR, CD320, TCN1, TCN2) Absence of (262_264delGAG and 297delA) by targeted mutation analysis [17]
No pathogenic mutations by WES (coverage > × 20)
[14C]-propionate incorporation (f) 11.0 nmol/mg protein/18 h (normal 10.8 ± 3.7 nmol/mg protein/18 h)
[14C]-methylene tetrahydrofolate incorporation (f) 250 pmol/mg protein/18 h (normal 225 ± 165 pmol/mg protein/18 h)
[57Co]-cyanocobalamin uptake (f) 16.9 pg/106 cells (normal 13.2 ± 4.8 pg/106)
[57Co]-cyanocobalamin conversion to adenosylcobalamin (f) 5.7. % of intracellular cobalamin (normal 15.3 ± 4.2)
[57Co]-cyanocobalamin coversion to methylcobalamin (f) 53.0% (normal 58.0 ± 6.7)