Identification of compound heterozygous mutations p.Gly400Val and p.Arg532Ter of the F11 gene in a Chinese patient with hereditary factor XI deficiency / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the phenotype and genotype defect characteristics of a Chinese patient with hereditary factor XI deficiency.</p><p><b>METHODS</b>The activated partial thromboplastin time (APTT), prothrombin time (PT), FXI activity (FXI:C) of the proband and his relatives were measured by a clotting method using automatic coagulation analyzer. FXI antigen (FXI:Ag) was assayed by enzyme-linked immunosorbent assay (ELISA). Fifteen exons of the F11 gene were amplified by PCR and sequenced. Pymol software was used to analyze the novel mutations.</p><p><b>RESULTS</b>The APTT of the proband was significantly prolonged (70.3 s, reference 34.5 s) with decreased FXI activity (6%, reference 50%-150%) and FXI antigen (1.9%, reference 50%-150%). The FXI activity and FXI antigen of his son was 31% and 39%, respectively. Two heterozygous F11 mutations were identified in the proband, which included a G to T substitution at nucleotide 1296 in exon 11 resulting in substitution of glycine by valine at codon 400 (p.Gly400Val) and a A to T substitution at nucleotide 1691 in exon 14 resulting in substitution of arginine (AGA) by a termination codon (TGA) at codon 532 (p.Arg532Ter). Analysis using Pymol indicated that the number of hydrogen bonds has changed, which led to a transformation of the structure of the FXI protein. The son of the proband was found to be heterozygous for the c.1296G to T (p.Gly400Val) mutation. NM_13142 c.1691A to T (p.Arg532Ter) is a novel mutation based on HGMD professional 2016.4. Based on 2015 Guidelines of ACMG, it is PVS1 (very strong pathogenicity).</p><p><b>CONCLUSION</b>The compound heterozygous mutations of F11 NM_13142 c.1296G to T (p.Gly400Val) and F11 NM_13142 c.1691A to T(p.Arg532Ter) probably underlies the FXI deficiency in the proband.</p>

Genotypic and phenotypic analysis of a case with inherited coagulation factor X deficiency / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the correlation between F10 gene mutation and its phenotype in a Chinese pedigree affected with FX deficiency.</p><p><b>METHODS</b>Prothrombin time(PT), activated partial thromboplastin time(APTT), fibrinogen, FII activity(FII:C), FVII activity(FVII:C), FIX activity (FIX:C), FX activity(FX:C) were determined with a one-stage clotting assay. The FX antigen(FX:Ag) was detected with an enzyme linked immunosorbent assay(ELISA). The 8 exons, introns and 5' and 3' untranslated regions(UTR) of the F10 gene of the proband and her family members were subjected to PCR amplification and Sanger sequencing. Suspected mutation was confirmed by reverse sequencing. Polymorphisms were excluded by direct sequencing of 100 healthy individuals.</p><p><b>RESULTS</b>The PT and APTT of the proband have prolonged to 16.1 s and 49.0 s, respectively. Her FX:C and FX:Ag were reduced by 27% and 56%, and her mother's PT, APTT, FX:C and FX:Ag were 14.8 s, 37.4 s, 44%, 34%, respectively. Her grandmother's PT, APTT, FX:C and FX:Ag were 15.8 s, 42.2 s, 31%, 45%, respectively. The results of her father and other family members were all within the normal range. Genetic analysis has revealed a heterozygous G to A mutation in the proband at position 28076 in exon 8 of the F10 gene, which resulted in a p.Gly363Ser substitution. The same mutation was also found in her mother and grandmother. No mutation of the F10 gene was found in her father. Gly363Ser may result in changes in the secondary structure of the FX protein and reduction of its activity.</p><p><b>CONCLUSION</b>The g.28076G to A(p.Gly363Ser) mutation of the F10 gene probably underlies the FX deficiency in this pedigree. The mutation was discovered for the first time in Chinese patients.</p>