Table 2 Measurement of the residual enzyme activity in control fibroblasts and fibroblasts with MTHFR deficiency using LC-MS/MS.

From: Development of a novel liquid chromatography-tandem mass spectrometry based enzymatic assay of 5,10-methylenetetrahydrofolate reductase

Enzyme activity LC-MS/MS

 

Standard

− FAD a

 

pmol/min/

mg protein

pmol/min/

mg protein

Control (n = 13)

Mean

SD

Range

338.5

96.5

240.1–624.0

333.2

85.4

213.9–575.4

Case

Age b

Sex

Enzyme activity

LC-MS/MS

Enzyme activity

HPLC-FLD c

Nucleotide

change d

Predicted Amino

acid change

   

Standard

− FAD a

Standard

  
   

pmol/min/

mg protein e

pmol/min/

mg protein e

pmol/min/

mg protein e

  

110

2 m

F

2.99

(0.79%)

2.28

(0.60%)

4.50

(1.0%)

c.446_447delinsTT

p.Gly149Val

211

15 y

M

51.3

(13.6%)

46.7

(12.4%)

46.7

(11.1%)

c.446_447delinsTT

c.137G > A

p.Gly149Val

p.Arg46Gln

3

20 y

M

7.34

(1.9%)

7.27

(1.9%)

11.2

(2.6%)

c.780G > C

c.996G > A

p.Gln260His(splicing)

p.Val332=(splicing)

4

24 y

M

34.9

(9.2%)

37.2

(9.9%)

32.5

(7.5%)

c.1724T > G

p.Val575Gly

514

35 y

F

27.5

(7.3%)

23.8

(6.3%)

17.5

(4.1%)

c.665 C > T

c.673 A > C

p.Ala222Val

p.Ile225Leu

  1. LC-MS/MS, liquid chromatography-tandem mass spectrometry; HPLC-FLD, high-performance liquid chromatography-fluorescence detection; FAD, flavin adenine dinucleotide; SD, standard deviation; m, months; y, years; M, male; F, female a, enzyme activity without FAD; b, age at onset; c, enzyme activity previously measured with HPLC-FLD; d, Numbering of nucleotide change in MTHFR gene follows the nomenclature NM_005957.5; e, % of the mean control value is shown in parentheses.
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