Abstract: Objective To strengthen the understanding of hereditary factor Ⅻ (FⅫ) deficiency. Methods The clinical data of hereditary coagulation factor Ⅻ (FⅫ) deficiency caused by compound heterozygous variation in a child were retrospectively analyzed and the related literatures in recent 10 years were reviewed. Results A girl was found to have abnormal coagulation function due to inguinal hernia surgery at the age of 6 . She has no bleeding, chronic disease history or family history. The coagulation function showed that activated partial thromboplastin time (APTT) was significantly prolonged, prothrombin time (PT) was normal, and APTT correction test (immediate and delayed) could be corrected. The plasma coagulation factor activity (Ⅻ:C) was 1 . 3 % (reference range: 50 %- 150 %). Two heterozygous variations were detected in F12 gene in the child by gene sequencing. The variation of c.G 1681 A (nucleotide 1681 in coding region changing from G to A) in exon 14 came from the mother, and the variation of c.G 1330 T (nucleotide 1330 in coding region changing from G to T) in exon 11 came from the father. The parents of the child were carriers, and they had no spontaneous bleeding. It was determined as pathogenic variation by ACMG. Conclusion Genetic testing is helpful for the diagnosis of hereditary FⅫ deficiency and the genetic variation information of hereditary FⅫ deficiency can be found.

Key words: inherited coagulation factor 竇? deficiency; APTT extension; genetic diagnosis