COLD-PCR and microarray: two independent highly sensitive approaches allowing the identification of fetal paternally inherited mutations in maternal plasma.

BACKGROUND: Until now, non-invasive prenatal diagnosis of genetic diseases found only limited routine applications. In autosomal recessive diseases, it can be used to determine the carrier status of the fetus through the detection of a paternally inherited disease allele in cases where maternal and paternal mutated alleles differ. METHODS: Conditions for non-invasive identification of fetal paternally inherited mutations in maternal plasma were developed by two independent approaches: coamplification at lower denaturation temperature-PCR (COLD-PCR) and highly sensitive microarrays. Assays were designed for identifying 14 mutations, 7 causing ß-thalassaemia and 7 cystic fibrosis. RESULTS: In total, 87 non-invasive prenatal diagnoses were performed by COLD-PCR in 75 couples at risk for ß-thalassaemia and 12 for cystic fibrosis. First, to identify the more appropriate methodology for the analysis of minority mutated fetal alleles in maternal plasma, both fast and full COLD-PCR protocols were developed for the most common Italian ß-thalassaemia Cd39 and IVSI.110 mutations. In 5 out of 31 samples, no enrichment was obtained with the fast protocol, while full COLD-PCR provided the correct fetal genotypes. Thus, full COLD-PCR protocols were developed for all the remaining mutations and all analyses confirmed the fetal genotypes obtained by invasive prenatal diagnosis. Microarray analysis was performed on 40 samples from 28 couples at risk for ß-thalassaemia and 12 for cystic fibrosis. Results were in complete concordance with those obtained by both COLD-PCR and invasive procedures. CONCLUSIONS: COLD-PCR and microarray approaches are not expensive, simple to handle, fast and can be easily set up in specialised clinical laboratories where prenatal diagnosis is routinely performed.

Prevalence of CYP2C9 polymorphisms in the south of Europe.

CYP2C9 is a major liver enzyme responsible of the metabolism of many clinically important drugs. The presence of CYP2C9 genetic polymorphisms has been associated with marked interindividual variability in its catalytic activity that could result in drug toxicity. Here we present frequencies of the most common CYP2C9 coding variants CYP2C9*2 (C430T) and CYP2C9*3 (A1075C) in representative samples of four regions from Spain (Basque Country, n=358; Catalonia, n=240; Central Spain, n=190 and Galicia, n=288) and one northern Italian region, (Verona, n=164), which range between 0.125 and 0.165 in the case of CYP2C9*2 and between 0.071 and 0.085 for CYP2C9*3. No significant differences between CYP2C9 allele frequencies were found comparing all the sampled populations. A more extensive comparative analysis using allele frequency data of populations widely spread over Europe was performed, showing significant differences in the CYP2C9*2 allele frequencies distribution between some of the regions, being quite homogeneous in the case of CYP2C9*3 variant. The results obtained show that above 40% of our samples carry a mutate allele, which can result in a poor metabolization of low therapeutic index drugs as oral anticoagulants (warfarin, acenocoumarol), oral antidiabetic drugs and some non-steroidal anti-inflammatory drugs. Our study constitutes both a large (n=1240) and robust allele frequency database on CYP2C9 polymorphisms, which represents one of the most numerous CYP2C9*2 and *3 database existing to date.

Lung function comparison between two decades in cystic fibrosis children: A single centre study.

OBJECTIVES: The purpose of this study was to compare two cohorts of cystic fibrosis (CF) patients born and treated in two different decades, diagnosed through a CF neonatal screening program. METHODOLOGY: We compared pulmonary function decline from 10 to 15 years of age in patients with cystic fibrosis born between 1979 and 1984 (Cohort 1) and between 1991 and 1996 (Cohort 2). Forced expiratory volume in 1 sec (FEV1%) and forced expiratory flow from 25% to 75% (FEF 25-75%) were analyzed by a linear mixed model approach. The differences between the two cohorts were estimated and the overall cohort effect was tested. RESULTS: Ninety-two patients (51 males, 41 females) fulfilled the selection criteria. Pancreatic insufficiency and CF related diabetes were present in 91% and 20% of patients, respectively. The mean absolute decrement of FEV1% was 9.2 (standard deviation [SD] 11.2) in Cohort 1 and 0.6 (SD 10.4) in Cohort 2 (P < 0.001). The mean decrement of FEF 25-75% was 16.3 (SD 19.5) in Cohort 1 and 1.3 (SD 16.8) in Cohort 2 (P < 0.001) and the Pseudomonas aeruginosa (Pa) colonization was 28% and 15% respectively (P = 0.1). CONCLUSIONS: Our results show that pulmonary function has clearly ameliorated over a decade in young CF patients, in a period during which several significant therapeutic changes have been introduced, such as dornase alfa, tobramycin and hypertonic saline. To our knowledge this is the first study showing a cohort effect in patients diagnosed after neonatal screening.