Jacky Cutler

Heterozygous factor XI deficiency associated with three novel mutations

To determine the utility of single‐stranded conformation polymorphism (SSCP) analysis for screening mutations in the factor XI (fXI) gene, we investigated three patients with heterozygous factor XI deficiency. DNA sequence analysis confirmed three novel mutations; a CGC → TGC (Arg308Cys) mutation in exon 9, a GCT→GTT (Ala412Val) mutation in exon 11 and an AGC → AGA (Ser576Arg) mutation in exon 15. We postulated on the structural implications of these missense mutations. Our results demonstrated that genotypic analysis is a useful tool for conclusive differentiation between heterozygous factor XI deficiency and normal subjects.

Vitamin K metabolism: Current knowledge and future research

Vitamin K is an essential fat-soluble micronutrient that is required for the post-translational γ-carboxylation of specific glutamic acid residues in hepatic and extra-hepatic proteins involved in blood coagulation and preventing cartilage and vasculature calcification. In humans, sources of vitamin K are derived from plants as phylloquinone and bacteria as the menaquinones. Menadione is a synthetic product used as a pharmaceutical but also represents an intermediate in the tissue-specific conversion of vitamin K to menaquinone-4, which preferentially resides in tissues such as brain. Research into vitamin K metabolism is essential for the understanding of vitamin K biology in health and disease. Progress in this area, driven by knowledge of vitamin K and the availability of markers of vitamin K status, has already proved beneficial in many areas of medicine and further opportunities present themselves. Areas of interest discussed in this review include prophylactic administration of vitamin K1 in term and preterm neonates, interactions between vitamins K and E, the industrial conversion of vitamin K to dihydro-vitamin K in foods, tissue-specific conversion of vitamin K to menaquinone-4, the biological activity of the five and seven carbon metabolites of vitamin K and circadian variations.

Rapid Genetic Diagnosis in Neonatal Pulmonary Artery Thrombosis Caused by Homozygous Antithrombin Budapest 3

We report a case of spontaneous left pulmonary artery thrombosis in a 3-day-old male neonate. The presenta tion of heparin resistance and thrombosis raised the possibility of a type II heparin binding site antithrombin deficiency. A continuous infusion of antithrombin concentrate was used suc cessfully, following failure of plasma, to correct the heparin resistance. Rapid genetic analysis allowed sequencing of the antithrombin gene within 5 working days. This showed the infant to be homozygous for the substitution of C to T at nucleotide 2759. This base change causes mutation of the na tive leucine at codon 99 to a phenylalanine. This antithrombin variant has been previously reported (antithrombin Budapest 3) and results in reduced binding of heparin to antithrombin. Such a molecular diagnostic approach is feasible and warranted in such cases of neonatal thrombosis because of the diagnostic difficulties encountered.

Third trimester amniocentesis for diagnosis of inherited bleeding disorders prior to delivery

X‐linked and autosomally inherited bleeding disorders confer a risk of foetal intracranial haemorrhage during delivery. Conventional prenatal diagnosis involving chorionic villus sampling or early amniocentesis is primarily aimed at offering the choice of pregnancy termination. Currently, non‐invasive procedures, involving analysis of free foetal DNA in the maternal circulation, are restricted to gender determination, and are of limited value in women at risk of carrying a foetus with a bleeding disorder. These limitations, together with the rising proportion of women shown to be carrying an affected foetus, who decide to continue the pregnancy, have led to the development of prenatal mutation identification via late amniocentesis after 34 weeks of gestation, with the sole aim of directing delivery management. Although this approach has been documented in some cases of potential foetal anomaly, there are no previous reports of its use in women with heritable bleeding disorders. We report a single‐centre experience of this technique in managing nine such deliveries. Of these, three showed an affected foetus, five showed an unaffected foetus and in one case no result could be obtained. In the three affected cases and the one with the inconclusive result restrictive birth plans were implemented, whereas the five unaffected cases underwent routine obstetric management; with one delivery necessitating interventions which would have been contraindicated if foetal status had not been determined. Late amniocentesis is a safe technique for guiding delivery management in women with bleeding disorders where the mutation is known.

A diagnostic dilemma: variant Bernard–Soulier syndrome, a difficult clinical and genetic diagnosis

this position; the difference in hydrophobicity will cause loss of hydrogen bonds in the core of the protein and as a result disrupt correct folding. Given that the missense mutation of the gene leads to amino acid change, the differences in size, hydrophobicity and physicochemical properties of the resulting protein will influence its correct folding and spatial structure. Consequently, the activity of FVIII will be influenced, and this will result in haemophilia A. Author contributions