The effect of genetic and nongenetic factors on warfarin dose variability in Qatari population

The objective of this study is to estimate the prevalence of VKORC1, CYP2C9, and CYP4F2 genetic variants and their contribution to warfarin dose variability in Qataris. One hundred and fifty warfarin-treated Qatari patients on a stable dose and with a therapeutic INR for at least three consecutive clinic visits were recruited. Saliva samples were collected using Oragene DNA self-collection kit, followed by DNA purification and genotyping via TaqMan Real-Time-PCR assay. The population was stratified into derivation and validation cohorts for the dosing model. The minor allele frequency (MAF) of VKORC1 (-1639G>A) was A (0.47), while the MAF's for the CYP2C9*2 and *3 and CYP4F2*3 were T (0.12), C (0.04) and T (0.43), respectively. Carriers of at least one CYP2C9 decreased function allele (*2 or *3) required lower median (IQR) warfarin doses compared to noncarriers [24.5 (14.5) mg/week vs. 35 (21) mg/week, p < 0.001]. Similarly, carriers of each additional copy of (A) variant in VKORC1 (-1639G>A) led to reduction in warfarin dose requirement compared to noncarriers [21(7.5) vs. 31.5(18.7) vs. 43.7(15), p < 0.0001]. CYP4F2*3 polymorphism on the other hand was not associated with warfarin dose. Multivariate analysis on the derivation cohort (n = 104) showed that a dosing model consisting of hypertension (HTN), heart failure (HF), VKORC1 (-1639G>A), CYP2C9*2 & *3, and smoking could explain 39.2% of warfarin dose variability in Qataris (P < 0.001). In the validation cohort (n = 45), correlation between predicted and actual warfarin doses was moderate (Spearman's rho correlation coefficient = 0.711, p < 0.001). This study concluded that VKORC1 (-1639G>A), CYP2C9*2 & *3 are the most significant predictors of warfarin dose along with HTN, HF and smoking.

Improved neurological outcome in children with chronic renal disease from infancy

Progressive encephalopathy, developmental delay, microcephaly, electroencephalogram (EEG) and computed tomographic (CT) scan abnormalities have been reported in 80% of children with chronic renal failure (CRF) in infancy. Malnutrition, aluminium intoxication and psychosocial deprivation are proposed as causes. In 15 children with CRF from infancy we evaluated the effect of no aluminium salts and early vigorous nutritional and psychosocial support, in addition to the standard therapy, on neurological development. Six patients underwent dialysis (2 at birth) and 3 received transplants. None of our patients were given aluminium therapy. The nutritional status of the patients in the first 2 years of life was assessed with the waterlow classification. At the end of the follow-up period (mean 50 months range 14-148 months), patients underwent neurodevelopmental assessment, head CT scan, EEG, nerve conduction velocity (NCV) and auditory brain stem evoked response (ABER). None of our patients developed progressive encephalopathy or recurrent seizures. All have a normal neurological examination apart from hypotonia. Microcephaly was present in 5 patients. There was a good correlation between malnutrition in the first 2 years of life and microcephaly. Developmental delay was present in 3 patients; all 3 were microcephalic. There was evidence of brain atrophy on CT scan in only 3 patients. EEG was abnormal in 6 patients, but only severe in 1 patient. Only 1 patient had diminished NCV; all patients had a normal ABER. We conclude that a policy of no oral aluminium therapy and early nutritional support leads to better neurological outcome in children with CRF from infancy.

Erythrocyte glucose-6-phosphate dehydrogenase status of newborns and adults in eastern Libya

One hundred and twenty cord and 320 venous blood samples were collected from Libyan newborns and adults respectively for the estimation of glucose-6-phosphate dehydrogenase (G-6-PD) activity by a screening technique and by quantitative estimation. The mean (S.D.) enzyme activity in the non-deficient neonates and adults was 1.13 (0.23) and 0.87 (0.21) IU/ml RBC/min respectively. The incidence of G-6-PD deficiency in the male population was 2.8%. The enzyme activity in the deficient male population ranged from 0-19.5%; none of them was symptomatic or had haematological abnormality. Of the female subjects 1.8% had enzyme activity of 50-65%. The frequency of enzyme deficiency appears to be low compared with that found in other Arab populations and is comparable with the incidence in other mediterranean countries.

Serum concentrations of vitamin D metabolites in maternal and umbilical cord blood of Libyan and Norwegian women

The serum concentrations of the vitamin D metabolites 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D (1,25-(OH)2D) and 24,25-dihydroxyvitamin D (24,25-(OH)2D), and vitamin D binding protein, calcium, phosphate and alkaline phosphatase were determined in 19 grand multiparous Libyan women at delivery, and in the umbilical cord blood of 14 of their babies. The results were compared with similarly collected data from 22 vitamin D-supplemented Norwegian mother-infant pairs. The median 25-OHD and 24,25-(OH)2D concentrations were significantly lower for the Libyan group (maternal 25-OHD: 34 vs 112 nmol/l; cord 25-OHD: 20 vs 76 nmol/l; maternal 24,25-(OH)2D: 0.6 vs 4.1 nmol/l; cord 24,25-(OH)2D: 0.4 vs 2.7 nmol/l, P less than 0.001 for all differences). In both groups the 25-OHD and 24,25-(OH)2D levels in maternal as well as in cord blood were closely associated (P less than 0.001). The median 1,25-(OH)2D level was similar for the two maternal groups (198 vs 194 pmol/l), but slightly lower for the Libyan than for the Norwegian cord samples (80 vs 93 pmol/l, P = 0.04). A calculated free 1,25-(OH)2D concentration (not bound to vitamin D binding protein) did not differ between the two maternal or cord groups. Calcium and phosphate concentrations were similar for the respective maternal and cord samples, while the median alkaline phosphatase level of cord blood was slightly higher for the Libyan group (P = 0.04). The results suggest that calcium and phosphate homoeostasis of pregnant women and their fetuses can be maintained despite wide variations in vitamin D supply and numerous repeated pregnancies.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypochloremic alkalosis in infants associated with soy protein formula

Thirteen infants, 2 to 10 months of age, developed hypochloremic alkalosis (serum chloride 59 to 92 mEq/l) while taking Neo-Mull-Soy (Syntex), a soy-based formula low in chloride (measured to be 0 to 2 mEq/l) but with considerable potassium citrate. Range of symptoms included lethargy, anorexia, mild spitting up, diarrhea, hematuria, and growth failure. Urine chloride excretion was less than 3 mEq/l. Plasma renin activity or aldosterone, measured in six infants, was elevated. All responded promptly to supplemental salt. One infant receiving Neo-Mull-Soy redeveloped alkalosis when supplemental salt was discontinued. Two of nine apparently normal infants receiving Neo-Mull-Soy also had hypochloremia (85, 86 mEq/l). Three of four receiving Prosobee (Mead Johnson; Cl content 7 mEq/l) had urine chloride concentration less than 20 mEq/l. The chloride content of some infant formulas is insufficient to offset salt losses following mild stress.