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Table 1 Pathogenic variants identified in the MMACHC/PRDX1 genes of epi-cblC patients

From: PRDX1 gene-related epi-cblC disease is a common type of inborn error of cobalamin metabolism with mono- or bi-allelic MMACHC epimutations

Pt Italian origin Diagnosis (age) Variant 1 Origin of variant 1 Variant 2 Origin of variant 2 Epimutation in MMACHC Age at epi-cblC molecular diagnosis Onset
1 Central C/B
(10 d)
MMACHC:c.271dupA p.(Arg91Lysfs*14) Paternal PRDX1:c.515-1G > T Maternal Het 10 y Early
2 Central NBS
(6 d)
MMACHC:c.666C > A p.(Tyr222*) Paternal PRDX1:c.515-1G > T Maternal Het 8 y Early
3 Southern C/B
(16 d)
MMACHC:c.271dupA p.(Arg91Lysfs*14) Paternal PRDX1:c.515-1G > T Maternal Het 11 y Early
4a Southern C/B
(2 m)
MMACHC:c.666C > A p.(Tyr222*) Maternal PRDX1:c.515-1G > T Paternal Het ND Early
5 Northern C/B
(2 m)
MMACHC:c.331C > T p.(Arg111*) Paternal PRDX1:c.515-1G > T Maternal Het 10 y Early
6 Northern C/B
(6 m)
MMACHC:c.481C > T p.(Arg161*) Paternal PRDX1:c.515-1G > T Maternal Het 6 y Early
7 Southern NBS
(1 m)
MMACHC:c.271dupA p.(Arg91Lysfs*14) Paternal PRDX1:c.515-1G > T Maternal Het 7 y Early
8 Southern C/B
(1 m)
MMACHC:c.271dupA p.(Arg91Lysfs*14) Maternal PRDX1:c.515-1G > T Paternal Het 18 y Early
9 Northern NBS
(4 d)
MMACHC:c.271dupA p.(Arg91Lysfs*14) Maternal PRDX1:c.515-1G > T Paternal Hetb 2 y Early
10 Northern C/B
(63 y)
MMACHC:c.617G > A p.(Arg206Gln) ND PRDX1:c.515-1G > T ND Het 75 y Late
11 Central NBS
(4 d)
PRDX1:c.515-1G > T Paternal PRDX1:c.515-1G > T Maternal Hom 7 y Early
  1. C/B, diagnosis of methylmalonic aciduria and homocystinuria performed after a clinical/biochemical assessment; d, days; m, months; het, heterozygous; hom, homozygous; NBS, diagnosis of methylmalonic aciduria and homocystinuria performed by expanded newborn screening; ND, not determined; y, years
  2. aWe identified the same genotype of Pt 4 in an abortion specimen of this family. Such foetus was biochemically affected
  3. bMethylation analysis of this patient has been previously reported by Gueant et al. [6]