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Archived Comments for: The 5, 10 methylenetetrahydrofolate reductase C677T mutation and risk of fetal loss: a case series and review of the literature

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  1. Caution with regard to generalizability of results

    David Somerset, University of Western Ontario

    6 March 2008

    This report provides weak evidence of benefit from anticoagulation during preganncy to women who are homozygous for the MTHFR C677T mutation and have a history of recurrent miscarriage. Of the three succesful outcomes: one mother had a history of two prior miscarriages and one full term pregancy; one had a history of two prior miscarriages only; and one had a history of 6 prior miscarriages and 3 full term pregnancies. Recurrent miscarriage is usually defined as three consecutive pregnancy losses, thus only the last of these patients could fullfil this definition, depending on the chronicity of her losses.

    Successful pregancy outcome is observed in 71-76% of women following 2 consecutive miscarriages, and 67-69% of women following 3 consecutive miscarriages (Stirrat (1990) Lancet 15;336(8716):673-5). Thus the observed results in these three women could easily have happened by chance.

    Of further concern, the prevalence of the MTHFR 667T/T genotype was reported to be 8% in an unselected newborn population from Wisconsin (Qi et al (2003) Genet Med. 5(6):458-9). Thus it is not uncommon to be homozygous for this mutation. To recommend treatment for a woman with no history of pregancy loss who is MTHFR 667T/T therfore seems over-enthusiastic.

    Competing interests