J Hematol

Journal of Hematology, ISSN 1927-1212 print, 1927-1220 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Hematol and Elmer Press Inc

Journal website https://jh.elmerpub.com

Original Article

Volume 15, Number 2, April 2026, pages 90-98

Identification and Pathogenicity Analysis of a Novel Fibrinogen Bβ Chain p.Gly293Val Variant Causing Hypofibrinogenemia

↓ Figure 3. Sanger sequencing chromatograms of the FGB gene. (a) Sequencing result of the proband showing a heterozygous missense variant c.878G>T (p.Gly293Val) in exon 6. The arrow indicates the nucleotide substitution (G>T). (b) Representative wild-type sequence at the same locus. Gly: glycine; Val: valine.

↓ Figure 4. Evolutionary conservation analysis of the Gly293 residue in the fibrinogen Bβ chain. Gly: glycine.

↓ Figure 5. Structural models of the wild-type and mutant fibrinogen Bβ chain around residue 293. (a) Wild-type Gly293. (b) Mutant-type Val293. All structures are displayed in cartoon representation with key residues shown as sticks. Green dashed lines indicate hydrogen bonds. Asp: aspartic acid; Gly: glycine; Phe: phenylalanine; Val: valine.

↓ **Table 1.** PCR Primers for the *FGA*, *FGB* and *FGG* Gene
Target region	Primer sequence (5'→3')	Annealing temperature (°C)
Exon A1	5'-CTTATAGAAAGCCTTCAGGG-3'	56 °C
	5'-GTGGAATAAACACCAGAGAG-3'
Exon A2	5'-ATCTCTGTGAGAGTGCCATC-3'	56 °C
	5'-TTTCTGGGACCAATCAGGTC-3'
Exon A3	5'-TGAATCTGAGAGATAGATCCTTACTG-3'	56 °C
	5'-TTTATTTAGGATTTTTGTTGTTTCTG-3'
Exon A4	5'-CAGCAGCTACTTCAATAACC-3'	56 °C
	5'-GTGCATAACTATCGCCTTCC-3'
Exon A5-1	5'-ACCAGGAACTCAATAGACGTAG-3'	56 °C
	5'-AGTTCCAGCTTCCAGCACTG-3'
Exon A5-2	5'-TATGGAACCGGATCAGAGAC-3'	56 °C
	5'-TGACACCTCTTCAAATGTGCC-3'
Exon A5-3	5'-ATCTGGAAGTTTTAGGCCAG-3'	56 °C
	5'-TGACAAACTCTCCTAACATAGG-3'
Exon A5-4	5'-TGATGAAGCTGCCTTCTTCG-3'	56 °C
	5'-AATGACGTGTAACAGAGAG-3'
Exon A6-1	5'-AGCCGTGCCTATCTTTGTAAAG-3'	56 °C
	5'-TTCATAGGAGGAGACTTGGAG-3'
Exon A6-2	5'-TCTGGCTAGGCAATGACTAC-3'	56 °C
	5'-AAGACAGAGTGCTCCCATTC-3'
Exon B1	5'-CTGAAGTCATTCCTAGCAGAG-3'	56 °C
	5'-CAATAAGTCAGAGGTTAACAATT-3'
Exon B2	5'-ATGAGGGTGTTGGAATAGTTAC-3'	56 °C
	5'-CAATAAGTCAGAGGTTAACAATT-3'
Exon B3	5'-AATGTCCATGACCCAAATC-3'	56 °C
	5'-ATGCTATTCACTAACCCAGAA-3'
Exon B4	5'-ATTCTCAGAAAATCAAAATTGTAT-3'	56 °C
	5'-ATGATCTGTTGGGAAAATCC-3'
Exon B5	5'-AAACTGGGTTGGACTTAC-3'	56 °C
	5'-ATTACAGGTATGAGCCAC-3'
Exon B6	5'-ATGGACAGGGGATTCAGATA-3'	56 °C
	5'-TAAAACAGGCTTCCAACAAT-3'
Exon B7	5'-GGCAGTTTTTAGTTTCCCA-3'	56 °C
	5'-ACAGTAAGTGCCCAGGAAGT-3'
Exon B8	5'-CTTGACCACCGTAGTTCTGT-3'	56 °C
	5'-GCTTGAGAGTTTTAGAGGAATA-3'
Exon G1+2	5'-GTGCAAAATCTGGGAACC-3'	55 °C
	5'-AAAGTTACAAGTGCCAGATGA-3'
Exon G3+4	5'-TAAATATCATCTGGCACTTGTA-3'	55 °C
	5'-ACTTCTATCTCTACTATGCTCAAC-3'
Exon G5	5'-TATTTGTGTTGGGAGTTGAGAC-3'	55 °C
	5'-TTACTTTTCACATCAGCATTCC-3'
Exon G6	5'-AAGGTTATATTGGGATTAGGTT-3'	55 °C
	5'-TTGCTTATTAGTTATGTGGTCTT-3'
Exon G7	5'-GCAACCCTAAGAAGTAACCAT-3'	55 °C
	5'-CCAAGAACCAAACAGACTCC-3'
Exon G8	5'-CCTACGAAAGAGGGAACT-3'	55 °C
	5'-ATGCCAAACTACTGGATA-3'
Exon G9	5'-ATGCACTTCGTAATAGACAGC-3'	55 °C
	5'-CTTTGTGGGTCAATAGAAGTTA-3'
Exon G10	5'-TGTCATTTATTTTGTCTTCGTA-3'	55 °C
	5'-ATGGGGTCTTTTGCTCTTA-3'

↓ Table 1. PCR Primers for the FGA, FGB and FGG Gene

Target region

Primer sequence (5'→3')

Annealing temperature (°C)

Exon A1

5'-CTTATAGAAAGCCTTCAGGG-3'

56 °C

5'-GTGGAATAAACACCAGAGAG-3'

Exon A2

5'-ATCTCTGTGAGAGTGCCATC-3'

56 °C

5'-TTTCTGGGACCAATCAGGTC-3'

Exon A3

5'-TGAATCTGAGAGATAGATCCTTACTG-3'

56 °C

5'-TTTATTTAGGATTTTTGTTGTTTCTG-3'

Exon A4

5'-CAGCAGCTACTTCAATAACC-3'

56 °C

5'-GTGCATAACTATCGCCTTCC-3'

Exon A5-1

5'-ACCAGGAACTCAATAGACGTAG-3'

56 °C

5'-AGTTCCAGCTTCCAGCACTG-3'

Exon A5-2

5'-TATGGAACCGGATCAGAGAC-3'

56 °C

5'-TGACACCTCTTCAAATGTGCC-3'

Exon A5-3

5'-ATCTGGAAGTTTTAGGCCAG-3'

56 °C

5'-TGACAAACTCTCCTAACATAGG-3'

Exon A5-4

5'-TGATGAAGCTGCCTTCTTCG-3'

56 °C

5'-AATGACGTGTAACAGAGAG-3'

Exon A6-1

5'-AGCCGTGCCTATCTTTGTAAAG-3'

56 °C

5'-TTCATAGGAGGAGACTTGGAG-3'

Exon A6-2

5'-TCTGGCTAGGCAATGACTAC-3'

56 °C

5'-AAGACAGAGTGCTCCCATTC-3'

Exon B1

5'-CTGAAGTCATTCCTAGCAGAG-3'

56 °C

5'-CAATAAGTCAGAGGTTAACAATT-3'

Exon B2

5'-ATGAGGGTGTTGGAATAGTTAC-3'

56 °C

5'-CAATAAGTCAGAGGTTAACAATT-3'

Exon B3

5'-AATGTCCATGACCCAAATC-3'

56 °C

5'-ATGCTATTCACTAACCCAGAA-3'

Exon B4

5'-ATTCTCAGAAAATCAAAATTGTAT-3'

56 °C

5'-ATGATCTGTTGGGAAAATCC-3'

Exon B5

5'-AAACTGGGTTGGACTTAC-3'

56 °C

5'-ATTACAGGTATGAGCCAC-3'

Exon B6

5'-ATGGACAGGGGATTCAGATA-3'

56 °C

5'-TAAAACAGGCTTCCAACAAT-3'

Exon B7

5'-GGCAGTTTTTAGTTTCCCA-3'

56 °C

5'-ACAGTAAGTGCCCAGGAAGT-3'

Exon B8

5'-CTTGACCACCGTAGTTCTGT-3'

56 °C

5'-GCTTGAGAGTTTTAGAGGAATA-3'

Exon G1+2

5'-GTGCAAAATCTGGGAACC-3'

55 °C

5'-AAAGTTACAAGTGCCAGATGA-3'

Exon G3+4

5'-TAAATATCATCTGGCACTTGTA-3'

55 °C

5'-ACTTCTATCTCTACTATGCTCAAC-3'

Exon G5

5'-TATTTGTGTTGGGAGTTGAGAC-3'

55 °C

5'-TTACTTTTCACATCAGCATTCC-3'

Exon G6

5'-AAGGTTATATTGGGATTAGGTT-3'

55 °C

5'-TTGCTTATTAGTTATGTGGTCTT-3'

Exon G7

5'-GCAACCCTAAGAAGTAACCAT-3'

55 °C

5'-CCAAGAACCAAACAGACTCC-3'

Exon G8

5'-CCTACGAAAGAGGGAACT-3'

55 °C

5'-ATGCCAAACTACTGGATA-3'

Exon G9

5'-ATGCACTTCGTAATAGACAGC-3'

55 °C

5'-CTTTGTGGGTCAATAGAAGTTA-3'

Exon G10

5'-TGTCATTTATTTTGTCTTCGTA-3'

55 °C

5'-ATGGGGTCTTTTGCTCTTA-3'

↓ **Table 2.** Phenotypes and Genotypes of the Family With Hereditary Fibrinogen Deficiency
	Age	APTT (s)	PT (s)	TT (s)	D-D (mg/L FEU)	FDPs (µg/mL)	Fg:C (Fg-Clauss assay) (g/L)	Fg:C (Fg-PT der assay) (g/L)	Fg-Clauss/Fg-PT der	Fg:Ag (g/L)	FGB: p.Gly293Val
APTT: activated partial thromboplastin time; PT: prothrombin time; TT: thrombin time; D-D: D-dimer; FDPs: fibrin(ogen) degradation products; Fg:C: fibrinogen activity; Fg:Ag: fibrinogen antigen.
II2(proband)	35	52.9↑	14.4↑	32.0↑	0.27	4.03	0.76↓	0.96↓	0.79	0.99↓	+
I1 (father)	63	32.5	8.9	16.7	0.4	4.5	2.98	3.1	0.96	3.06	–
I2 (mother)	62	59.9↑	15.1↑	33.2↑	0.32	3.98	0.89↓	1.01↓	0.88	1.03↓	+
II1(brother)	33	55.7↑	15.8↑	31.4↑	0.41	3.75	0.92↓	1.05↓	0.88	1.22↓	+
II3(husband)	31	36.1	10	17.3	0.19	2.88	2.99	2.98	1	3.01	–
III1 (daughter)	7	54.3↑	14.9↑	30.9↑	0.39	4	0.95↓	0.99↓	0.96	1.10↓	+
Reference range		26.6–43.6	7.7–10.5	14.5–19.2	< 0.50	< 5.00	2.00–4.00	2.00–4.00	> 0.7	2.00–4.00	–

↓ Table 2. Phenotypes and Genotypes of the Family With Hereditary Fibrinogen Deficiency

Age

APTT (s)

PT (s)

TT (s)

D-D (mg/L FEU)

FDPs (µg/mL)

Fg:C (Fg-Clauss assay) (g/L)

Fg:C (Fg-PT der assay) (g/L)

Fg-Clauss/Fg-PT der

Fg:Ag (g/L)

FGB: p.Gly293Val

APTT: activated partial thromboplastin time; PT: prothrombin time; TT: thrombin time; D-D: D-dimer; FDPs: fibrin(ogen) degradation products; Fg:C: fibrinogen activity; Fg:Ag: fibrinogen antigen.

II2(proband)

52.9↑

14.4↑

32.0↑

0.27

4.03

0.76↓

0.96↓

0.79

0.99↓

I1 (father)

32.5

8.9

16.7

0.4

4.5

2.98

3.1

0.96

3.06

–

I2 (mother)

59.9↑

15.1↑

33.2↑

0.32

3.98

0.89↓

1.01↓

0.88

1.03↓

II1(brother)

55.7↑

15.8↑

31.4↑

0.41

3.75

0.92↓

1.05↓

0.88

1.22↓

II3(husband)

36.1

17.3

0.19

2.88

2.99

2.98

3.01

–

III1 (daughter)

54.3↑

14.9↑

30.9↑

0.39

0.95↓

0.99↓

0.96

1.10↓

Reference range

26.6–43.6

7.7–10.5

14.5–19.2

< 0.50

< 5.00

2.00–4.00

> 0.7

2.00–4.00

–

↓ **Table 3.** Results of Thrombin-Induced Fibrinogen Polymerization Assay
Parameter	Control	Proband	Unit
LT: lag time; Vmax: maximum slope; Amax: maximum absorbance.
LT	2.5 ± 0.3	2.7 ± 0.4	min
Vmax	25.5 ± 2.1	24.8 ± 2.5	mAbs/min
Amax	0.125 ± 0.010	0.122 ± 0.012	Abs (350 nm)

↓ Table 3. Results of Thrombin-Induced Fibrinogen Polymerization Assay

Parameter

Control

Proband

Unit

LT: lag time; Vmax: maximum slope; Amax: maximum absorbance.

2.5 ± 0.3

2.7 ± 0.4

min

Vmax

25.5 ± 2.1

24.8 ± 2.5

mAbs/min

Amax

0.125 ± 0.010

0.122 ± 0.012

Abs (350 nm)

↓ **Table 4.** Thrombelastography Test Results of the Family With Hereditary Fibrinogen Deficiency
	R (min)	K (min)	α (°)	MA (mm)	CI	LY30 (%)	EPL (%)
R: reaction time; K: kinetics time; α: alpha angle; MA: maximum amplitude; CI: coagulation index; LY30: the percentage of clot lysis at 30 min; EPL: estimated percent lysis.
II2 (proband)	7.7	6.3↑	30.0↓	40.5↓	–8.5↓	6.0	14.2
I1 (father)	7.4	2.2	62.7	68.2	–0.91	4.5	13.0
I2 (mother)	8.9	5.7↑	31.4↓	41.2↓	–6.3↓	5.3	6.9
II1(brother)	8.1	5.5↑	34.1↓	39.3↓	–6.8↓	3.1	10.9
II3 (husband)	9.3	2.5	60.5	70.0	0.7	5.7	8.5
III1 (daughter)	8.0	5.2↑	31.5↓	44.1↓	–5.2↓	4.1	4.9
Reference range	5.0–10.0	1.0–3.0	50.0–70.0	53.0–72.0	–3.0–3.0	0.0–8.0	0.0–15.0

↓ Table 4. Thrombelastography Test Results of the Family With Hereditary Fibrinogen Deficiency

R (min)

K (min)

α (°)

MA (mm)

LY30 (%)

EPL (%)

R: reaction time; K: kinetics time; α: alpha angle; MA: maximum amplitude; CI: coagulation index; LY30: the percentage of clot lysis at 30 min; EPL: estimated percent lysis.

II2 (proband)

7.7

6.3↑

30.0↓

40.5↓

–8.5↓

6.0

14.2

I1 (father)

7.4

2.2

62.7

68.2

–0.91

4.5

13.0

I2 (mother)

8.9

5.7↑

31.4↓

41.2↓

–6.3↓

5.3

6.9

II1(brother)

8.1

5.5↑

34.1↓

39.3↓

–6.8↓

3.1

10.9

II3 (husband)

9.3

2.5

60.5

70.0

0.7

5.7

8.5

III1 (daughter)

8.0

5.2↑

31.5↓

44.1↓

–5.2↓

4.1

4.9

Reference range

5.0–10.0

1.0–3.0

50.0–70.0

53.0–72.0

–3.0–3.0

0.0–8.0

0.0–15.0