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Prevalence of the factor V Leiden mutation in portal and hepatic vein thrombosis
  1. R DAS,
  2. G GAREWAL
  1. Department of Haematology,
  2. Postgraduate Institute of Medical Education and Research,
  3. Chandigarh 160 012, India
  4. Department of Hepatology
  1. Professor G Garewal.
  1. Y CHAWLA,
  2. R K DHIMAN
  1. Department of Haematology,
  2. Postgraduate Institute of Medical Education and Research,
  3. Chandigarh 160 012, India
  4. Department of Hepatology
  1. Professor G Garewal.

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Editor,—We read with great interest the article by Mahmoud et al(Gut1997;40:798–800) on the prevalence of factor V Leiden (FVL) mutation in hepatic and portal vein thrombosis. In the past few years the FVL mutation has emerged as the commonest genetic risk factor for venous thrombosis.1 The FVL mutation seems to be most prevalent in Europe, extending to northern India in the east and Saudi Arabia in the south.2 The two striking features of the population genetics of the FVL mutation are the confined racial distribution and the high prevalence in European peoples (allele frequencies ranging from 1.4 to 7%). We have found an allele frequency of 1.9% for the FVL mutation in 130 unrelated subjects from northern India who had no predisposing cause or family history of thrombosis.3

In India portal vein thrombosis (PVT) and hepatic vein thrombosis (Budd-Chiari syndrome) are frequently encountered hepatic disorders causing portal hypertension. In a series of patients with PVT from our institute the cause of disease could be elucidated in only 17 of the 213 cases.4 Umbilical sepsis led to PVT in 13 patients and congenital heart disease was responsible in four. Budd-Chiari syndrome represents a spectrum of disease primarily caused by a hypercoagulable state. Analysis of our cases of Budd-Chiari syndrome revealed the aetiology in 65 of the 177 patients.5 In four patients Budd-Chiari syndrome was associated with polycythaemia vera and in three with paroxysmal nocturnal haemoglobinuria. It has been well recognised that the clinical course, outcome and aetiopathogenic factors leading to PVT and Budd-Chiari syndrome are substantially different in the East and West.

As the FVL mutation has recently been detected in our population we attempted to study cases of PVT and Budd-Chiari syndrome to evaluate the role of this mutation in the aetiopathogenesis of these two conditions. Twenty three cases of PVT and nine cases of Budd-Chiari syndrome, including the five reported in our previous study,3 constituted the study group. The FVL mutation was detected as described by Bertina and colleagues.6 Genomic DNA was extracted from leucocytes by chloroform-phenol extraction, amplified using the polymerase chain reaction using specific primers, and the product was digested with the Mnl1 restriction enzyme. One of the 23 patients with PVT and two of the nine patients with Budd-Chiari syndrome were heterozygous for the FVL mutation. None of the patients was homozygous for the mutation. Another case of Budd-Chiari syndrome was associated with polycythaemia vera.

The prevalence of FVL mutation in our small series seems to be higher in patients with Budd-Chiari syndrome than in those with PVT or in controls. Therefore we concur with Mahmoud et al’s observation that screening for the FVL mutation is important in patients with Budd-Chiari syndrome. However, in cases of idiopathic PVT this mutation does not seem to have a major pathogenic role.

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