Materials and Methods: This study was conducted on 12 patients with inherited deficiency of prothrombin. Early diagnosis was based on clinical symptoms, laboratory evaluation, and family history. Then, the function level of prothrombin was measured, the initial diagnosis of disease was confirmed, and polymerase chain reaction (PCR) analysis was performed. Finally, gene sequencing and genotyping of factor II was done.

Results: Molecular analysis indicated a point mutation in exon 7 in three patients and a frameshift mutation in exon 14 due to addition of a thymine base at position 1760-1761 in one patient, both of which have been reported for the first time.

Conclusions: Molecular methods performed on patients from Southeastern Iranian population in terms of coagulation factor II deficiency revealed a substitution mutation in exon 7 in three patients and a frameshift mutation in exon 14 in one patient, both of which were reported for the first time. Considering the significant difference between the clinical symptoms of the present study and previous studies, probably the type of mutations reported in this study (for the first time) caused these clinical symptoms, but statistical studies did not show any relationship between the type of mutation and the occurrence of clinical symptoms. And it needs more investigations on more patients, with a larger population.