Table 1 Genetic and biochemical findings of validation and discovery cases

TCN2 ^a

c.497_498delTC (p.Leu166Profs*7) CD106933

c.497_498delTC (p.Leu166Profs*7) CD106933

2 m pancytopenia, FTT, metabolic acidosis. Improvement after im OHCbl

↑Hcys (pl): 26 μmol/L; ↑C3: 3.4 μmol/L; ↑MMA (ur): 419 mmol/mol creatn

Propionate uptake (FB) (nmol/10 h/mg prot): Normal

-OHCbl (patient/control): 0.76/0.97

+OHCbl (patient/control): 0.98/0.83

MTR ^a

c.1348_1349delTCinsGA (p.Ser450Asp)

c.3008-4A > G (p.?) CS135282

2 m apnea, somnolence, hypotonia, seizures

↑Hcys (pl): 79 μmol/L; MMA (ur) (N)

MTRR

c.1361C > T (p.Ser454Leu) CM032288

c.1769 + 1G > A (p.Glu560_Arg590del)

MGA, low serum vit B12; ↑Hcys (pl): 90 μmol/L; N MMA (ur)

MMACHC

c.271dupA (p.Arg91Lysfs*14) CI055013

c.271dupA (p.Arg91Lysfs*14) CI055013

NBS: ↑C3 + C3/C2 in DBS

↑Hcys (pl); ↑MMA (ur) > 1000 mmol/mol creatn

MMACHC ^a

c.271dupA (p.Arg91Lysfs*14) CI055013

c.626dupT (p.Thr210Aspfs*35) CI095519

NBS: ↑C3 in DBS

↑Hcys: 159 μmol/L; C3 (pl): 8.2 μmol/L; ↑MMA (ur): 608 mmol/mol creatn

Propionate uptake (FB) (nmol/10 h/mg prot):

-OHCbl (patient/control): 0.23/1.90

+OHCbl (patient/control): 2.3/2.34

MMADHC ^a

c.57_64del8 (p.Ser20*) CD082071

c.57_64del8 (p.Ser20*) CD082071

4d hypotonia, metabolic acidosis, hyperammonemia

N Hcys (pl); ↑MMA (ur): 5875 mmol/mol creatn;

Propionate uptake (FB) (nmol/10 h/mg prot):

-OHCbl (patient/control): 0.13/3.31

+OHCbl (patient/control): 2.30/3.37

Mutase (FB):N

MUT ^a

c.312delC (p.Trp105Glyfs*75)

c.1846C > T (p.Arg616Cys) CM050688

12 m metabolic acidosis

↑MMA (ur): 8810 mmol/mol creatn

MMAA ^a

c.64C > T (p.Arg22Ter) CM042745

c.433C > T (p.Arg145Ter) CM042746

5 m metabolic acidosis. Improvement after im OHCbl

↑MMA (ur)

Propionate uptake (FB) (nmol/10 h/mg prot):

-OHCbl (patient/control): 0.12/1.32

+OHCbl (patient/control): 0.42/2.17

Mutase (FB): N

MMAB ^a

c.548A > T (p.His183Leu) CM154654

c.570_572dupCCG (p.Arg191dup) CI154655

NBS: ↑C3 in DBS

↑C3 (pl): 7.7 μmol/L; ↑MMA (ur): 830 mmol/mol creatn

Propionate uptake (FB) (nmol/10 h/mg prot):

-OHCbl (patient/control): 0.63/1.90

+OHCbl (patient/control): 1.19/2.34

Mutase (FB): N

TCN1

c.901G > T^b (p.Asp301Tyr) CM099555

c.901G > T^b (p.Asp301Tyr) CM099555

Adult with neurological symptoms and low serum vit B₁₂. Improvement after im OHCbl

↑N Hcys (pl): 17 μmol/L

TCN1

c.901G > T^b (p.Asp301Tyr) CM099555

c.901G > T^b (p.Asp301Tyr) CM099555

Adult with slight anemia and low serum vit B12.

Improvement after im OHCbl

GIF ^a

c.389C > G (p.Ser130Ter)

c.389C > G (p.Ser130Ter)

7y, anemia since 15 m; low serum vit B12. Improvement after im OHCbl

↑Hcys (pl): 49 μmol/L

AMN ^a

c.514-34G > A (p.Thr172fs) CS127867

c.1046C > A (p.Ser349Ter)

2y, megaloblastic anemia with low serum vit B12. Improvement after im OHCbl

↑Hcys (pl): 39.9 μmol/L

MMAA

c.593_596delCTGA (p.Thr198Serfs*6) CD043681

c.593_596delCTGA (p.Thr198Serfs*6) CD043681

↑MMA (ur)

MUT ^a

c.904G > C (p.Ala302Pro)

c.904G > C (p.Ala302Pro)

NBS: ↑C3 + C3/C2 in DBS

↑MMA (ur): > 1000 mol/mol creatn

Propionate uptake (FB) (nmol/10 h/mg prot) - > (mut0)

-OHCbl (patient/control): 0.18/1.16

+OHCbl (patient/control): 0.11/1.02

MUT ^a

c.671_678dupAATTTATG (p.Val227Asnfs*16) CI050942

c.607G > A (p.Gly203Arg) CM002067

Neonatal presentation

↑MMA (ur)

MUT

c.313 T > C (p.Trp105Arg) CM900166

c.2150G > T (p.Gly717Val) CM920488

7 m metabolic acidosis, lethargy

↑MMA (ur)

MUT ^a

c.2026G > A (p.Ala676Thr)

c.2026G > A (p.Ala676Thr)

NBS: ↑C3/C2 in DBS

↑C3 (pl): 2.4 μmol/L; ↑MMA (ur): 772 mmol/mol creatn

Propionate uptake (FB) (nmol/10 h/mg prot) - > (mut-)

-OHCbl (patient/control): 0.25/1.16

+OHCbl (patient/control): 1.16/1.02

MUT ^a

c.243dupA (p.Pro82Thrfs*2)

c.1084-10A > G (p.?) CS128372

↑MMA (ur)

MUT ^a

TCN1^a

c.454C > T (p.Arg152Ter) CM050671 c.901G > T^b (p.Asp301Tyr) CM099555

?

NBS: ↑C3 in DBS

Low serum vit B12; ↑N MMA (ur): 17–58 mmol/mol creatn

MUT

c.671_678dupAATTTATG (p.Val227Asnfs*16) CI050942

c.671_678dupAATTTATG (p.Val227Asnfs*16) CI050942

Neonatal presentation and fatal outcome

↑MMA (ur)

MUT ^a

c.1420C > T (p. Arg474Ter) CM050685

c.2026G > A (p.Ala676Thr)

NBS: ↑C3/C2 in DBS

↑C3 (pl): 3.4 μmol/L; ↑MMA (ur): 276 mmol/mol creatn

Propionate uptake (FB) (nmol/10 h/mg prot) - > (mut-)

-OHCbl (patient/control): 0.28/1.33

+OHCbl (patient/control): 1.13/1.57

MMAB ^a

c.220G > T (p.Glu74Ter)

c.548A > T (p.His183Leu) CM154654

NBS: ↑C3/C2 in DBS

↑C3 (pl): 3.64 μmol/L; ↑MMA (ur): 68 mmol/mol creatn

CD320 ^a

c.262_264delGAG (p.Glu88del) CD104789

c.142 + 5G > A (p.?)

NBS: ↑C3 + C3/C2 in DBS

↑Hcys (pl): 18.3 μmol/L; N C3 + C4DC (pl); ↑MMA (ur): 25–170 mmol/mol creatn

MMACHC ^a

c.347 T > C (p.Leu116Pro) CM060067

c.347 T > C (p.Leu116Pro) CM060067

NBS: ↑C3 + C3/C2 in DBS

↑MMA (ur): 2000 mmol/mol creatn

MMACHC ^a

c.271dupA (p.Arg91Lysfs*14) CI055013

c.271dupA (p.Arg91Lysfs*14) CI055013

4d: hypotonia, weight loss, vomiting, ↑lac

↑Hcys (pl): 214 μmol/L; ↑C3: 6.5 μmol/L + ↑C4DC (pl): 0.25 μmol/L

↑MMA (ur): 1197 mmol/mol creatn

MMACHC

c.271dupA (p.Arg91Lysfs*14) CI055013

c.271dupA (p.Arg91Lysfs*14) CI055013

↑Hcys (pl); ↑MMA (ur)

MMADHC ^a

c.748C > T (p.Arg250Ter) CM081188

c.748C > T (p.Arg250Ter) CM081188

NBS: ↑C3 + C3/C2 in DBS

↑Hcys (pl): 51 μmol/L; ↑C3 (pl): 4.8 μmol/L; MMA (ur): 290 mmol/mol creatn

MMADHC ^a

c.748C > T (p.Arg250Ter) CM081188

c.748C > T (p.Arg250Ter) CM081188

NBS: ↑C3 + C3/C2 in DBS

↑Hcys (pl): 59 μmol/L; ↑C3 (pl): 8.5 μmol/L; MMA (ur): 1175 mmol/mol creatn

MTRR

c.1361C > T (p.Ser454Leu) CM032288

c.1361C > T (p. Ser454Leu) CM032288

17 m; anemia, psychomotor delay

↑Hcys (pl): 76 μmol/L

MTRR

c.1361C > T (p.Ser454Leu) CM032288

c.1678_1681delGAGA (p.Glu560Asnfs*42) CD159487

10 m seizures, megaloblastic anemia

↑Hcys (pl): 89 μmol/L

SUCLA2 ^a

c.976G > C (p.Gly326Arg)

c.935 T > C (p.Ile312Thr)

Hypoglycemia at birth, slight PMD during first years

Asymptomatic at 11y

↑-N C3(pl): 1–2.2 μmol/L + C4DC

↑N Lac, 3-OHProp, MMA 27 mmol/mol creatn, MC (ur)

Normal carboxylases activities (FB)

Propionate uptake (FB) (nmol/10 h/mg prot) - > Normal

-OHCbl (patient/control): 0.71/0.75

+OHCbl (patient/control): 0.79/1.13

ACSF3 ^a

c.424C > T (p.Gln142Ter)

c.1446_1447delCA (p.Tyr482Ter)

NBS: ↑MMA (ur) since newborn: 512 mmol/mol creatn

Asymptomatic at 3y

ACSF3 ^a

c.1075G > A (p.Glu359Lys) CM116777

c.1075G > A (p.Glu359Lys) CM116777

5y PMD, bilateral sensorineural hearing loss

AC (pl): N; ↑MMA (ur): 360 mmol/mol creatn

ACSF3 ^a

c.1075G > A (p.Glu359Lys) CM116777

c.1672C > T (p.Arg558Trp) CM116840

Seizures since first months of age

At 12y seizures + dystonia

AC (pl): N; ↑MMA (ur): 124–560 mmol/mol creatn

Normal propionate uptake ± OHCbl (FB)

ACSF3

c.820C > T (p.Gln274Ter)

c.820C > T (p.Gln274Ter)

NBS: ↑MMA (ur) since newborn. Asymptomatic at 7 m