Functional characterization of a novel missense mutation identified in a Turkish patient affected by severe coagulation factor V deficiency.

Factor V (FV) deficiency is a rare coagulation disorder, characterized by a bleeding phenotype varying from mild to severe. To date, 115 mutations have been described along the gene encoding for FV (F5) but only few of them have been functionally characterized. Aim of this study was the identification and the molecular characterization of genetic defects underlying severe FV deficiency in a 7-month-old Turkish patient. Mutation detection was performed by sequencing the whole F5 coding region, exon-intron boundaries and about 300 bp of the promoter region. Functional analysis of the identified missense mutation was conducted by transient expression of wild-type and mutant FV recombinant molecules in COS-1 cells. Two novel mutations: a missense (Pro132Arg) and a 1-bp deletion (Ile1890TyrfsX19) were identified in the F5 gene. While the frameshift mutation is responsible for the introduction of a premature stop codon, likely triggering F5 mRNA to nonsense-mediated mRNA degradation, the demonstration of the pathogenic role of the Pro132Arg mutation required an experimental validation. Expression experiments showed that the missense mutation causes a significant reduction in FV secretion and in the specific activity of the residual secreted molecule (77% and 78% decrease, respectively). This paper reports the identification of two novel mutations responsible for FV deficiency, thus widening the mutational spectrum of the F5 gene. The Pro132Arg mutation adds to the only other two functionally characterized missense defects in the FV A1 domain.

Screening of blood glucose levels in healthy neonates.

INTRODUCTION: This study aimed to screen the blood glucose levels in healthy term and near-term neonates, and to assess the influence of mode of delivery, birth weight and gestational age on blood glucose levels. METHODS: The blood glucose concentrations of 1,540 healthy term and near-term neonates in the first hour of life were retrospectively evaluated from the clinical charts. Glucose levels were estimated from heel prick capillary samples. The glucose concentration was correlated with the mode of delivery, birth weight and gestational age. RESULTS: Vaginally delivered neonates had higher glucose levels. The glucose concentrations were not significantly different between infants in the different birth weight groups. However, glucose concentration was significantly correlated with gestational age, and the levels were observed to rise with increasing gestational age. CONCLUSION: Screening asymptomatic, healthy term and near-term neonates for hypoglycaemia in the first hour following birth is unnecessary. Glucose strips and glucose meters are useful only as screening devices for neonatal hypoglycaemia, and a screening cut-off value must be established.

Purpura fulminans in a child with combined heterozygous prothrombin G20210A and factor V Leiden mutations.

Although thrombosis is relatively rare in children, reports of young patients with thrombosis are becoming more frequent with time. Activated protein C resistance and prothrombin 20210 A mutation are results of point mutations described in the last decade. This article highlights a case of a child with severe arterial thrombosis who was heterozygous for the factor V Leiden (FVL) and prothrombin G20210A mutations. The patient diagnosed with purpura fulminans was an 8-year-old boy who was referred to our hospital with purpuric lesions on the extremities and necrosis of the penis. We believe that the coexistence of more than one thrombophilic mutation contributed to the occurrence of severe thrombosis at a young age in this patient.

Significant differences between capillary and venous complete blood counts in the neonatal period.

The normal capillary and venous hematologic values for neonates have not been defined clearly. It is well known that capillary blood has higher hemoglobin (Hb) and hematocrit (Hct) values than venous blood. In a recent study, we reported differences between capillary and venous complete blood counts (CBC) in healthy term neonates on day 1 of life. The aim of this study was to extend our previous investigation. Term neonates (n=141) were stratified into four groups by days of postnatal age: group 2 (day 7, n=38), group 3 (day 14, n=35), group 4 (day 21, n=32) and, group 5 (day 28, n=36). Data from our previous study were included in the statistical analysis as group 1 (day 1, n=95). A CBC and differential count were carried out on each capillary and venous sample drawn simultaneously. Within each group, the mean and standard deviation for each parameter in capillary and venous blood were calculated and then compared using the paired sample t-test. In all groups, the capillary blood samples had higher Hb, Hct, red blood cell (RBC), white blood cell (WBC), and lymphocyte counts. In each group, venous platelet counts were significantly higher than the corresponding capillary values. There was also a trend toward higher venous mean corpuscular volume, higher capillary polymorphonuclear leukocyte (PML) count and mean platelet volume in all groups. In both capillary and venous blood, Hb, Hct, RBC, MCV values and WBC, lymphocyte, PML counts decreased and platelet counts increased steadily during neonatal period. This study reveals that CBC parameters and differential counts may differ depending on the blood sampling used. The findings underline the importance of considering the sample source when using hematologic reference ranges for healthy or septic neonates. When interpreting results, the term 'peripheral blood' should be replaced with 'capillary blood' or 'venous blood' so that an accurate assessment can be made.

Activated protein C resistance and false type 2 protein C deficiency detected after multiple shunt failures in a patient with hydrocephalus.

A 2-year-old hydrocephalic boy who had suffered multiple shunt failures was evaluated for hypercoagulability after a thrombus was removed from his right atrium. The work-up revealed that the patient had the heterozygous form of activated protein C resistance and false type 2 protein C deficiency by the clotting method. His protein C activity was normal by the chromogenic method. We suggest that patients having hydrocephalus, shunt-associated thrombus formation, or both should be evaluated for thrombophilic disorders, and protein C activity should be measured by chromogenic assay in patients with documented activated protein C resistance.