Placental markers of folate-related metabolism in preeclampsia

The etiology and degree of clinical symptoms of preeclampsia depend on genotypic and phenotypic maternal and trophoblast factors, and elevated levels of plasma homocysteine (Hcy) are one of the pathogenetic factors of preeclampsia. To assess the impact of the folate-related metabolism, we characterized the indices of this metabolism in 40 samples from uncomplicated term placentas and 28 samples from preeclamptic pregnancies by quantifying the total content of folate, methionine (Met), Hcy and related cysteine, and glutathione (GSH) in compliance with the 677 C/T genotype of methylene tetrahydrofolate reductase (MTHFR). The prevalence ofMTHFRgenotypes was not significantly different between the two groups. The polymorphism ofMTHFRwas not unambiguously connected with the content of total placental Met, Hcy and related cysteine, and GSH either in uncomplicated or in complicated pregnancies. By contrast, the combination of the heterozygousMTHFRgenotype with folate deficiency in the samples from preeclamptic pregnancies was characterized by a statistically significant decrease in the Met content, a trend toward increased Hcy levels and a tight association between metabolically directly and indirectly related compounds, e.g. positive relation between Hcy versus cysteine and folate versus GSH and negative relation between folate versus Hcy and both Hcy and cysteine versus GSH. We demonstrated the expression of cystathionine-β-synthase (CBS) in human placenta at term by RT-PCR and western blot analysis, for the first time, and confirmed its catalytic activity and the accumulation of cysteine and CBS in placental explants cultivated in the presence of elevated Hcy concentrations. We suggest that disturbance in placental folate-related metabolism may be one of the pathogenetic factors in preeclampsia.

Fibrinogen Poissy II (gammaN361K): a novel dysfibrinogenemia associated with defective polymerization and peptide B release

A fibrinogen variant was identified in a pregnant patient with disseminated intravascular coagulation and abruptio placentae. This dysfibrinogen was also found in four asymptomatic members of the patient's family. Coagulation studies showed prolongation of both the thrombin and reptilase times, and discrepancy was noted between the levels of plasma fibrinogen as determined by a kinetic versus an immunological determination or light-scattering assay. Studies on purified fibrinogen revealed an impaired release of fibrinopeptide B by thrombin related to a delayed thrombin-induced fibrin polymerization. DNA sequencing revealed a heterozygous T <-- A point mutation in position 9373 of the gamma-chain gene (exon 9), which substituted a K for an N at position 361.

Fibrinogen Saint-Germain I: a case of the heterozygous Aalpha GLY 12 --> VAL fibrinogen variant

A fibrinogen variant was suspected based on the results of routine coagulation tests in a 2-year-old asymptomatic child. Coagulation studies showed marked prolongation of both the thrombin and reptilase times, and discrepancy was noted between the level of plasma fibrinogen as measured by a kinetic versus immunological determination. Family studies revealed that the father beared the same abnormality. Studies of purified fibrinogen revealed an impaired release of both fibrinopeptides by thrombin. Fibrin monomer polymerization and fibrin stabilization were normal. DNA sequencing revealed a heterozygous G --> T point mutation in exon 2 of the gene coding for the Aalpha chain, which substituted a Gly for Val at position 12. Although the mutation is the same as in fibrinogen Rouen, fibrinogen Saint-Germain I shows a different fibrinopeptide release pattern and a mild factor V deficiency.