Gene conversion is a likely cause of mutation in PKD1

Approximately 70% of the gene responsible for the most common form of autosomal dominant polycystic kidney disease ( PKD1 ) is replicated in several highly homologous copies located more proximally on chromosome 16. We recently have described a novel technique for mutation detection in the duplicated region of PKD1 that circumvents the difficulties posed by these homologs. We have used this method to identify two patients with a nearly identical cluster of base pair substitutions in exon 23. Since pseudogenes are known to be reservoirs for mutation via gene conversion events for a number of other diseases, we decided to test whether these sequence differences in PKD1 could have arisen as a result of this mechanism. Using changes in restriction digest patterns, we were able to show that these sequence substitutions are also present in N23HA, a rodent-human somatic cell hybrid that contains only the PKD1 homologs. Moreover, these changes were also detected in total DNA from several affected and unaffected individuals that did not harbor this mutation in their PKD1 gene copy. This is the first example of gene conversion in PKD1 , and our findings highlight the importance of using gene-specific reagents in defining PKD1 mutations.      

Identification of isolate-specific sporozoite proteins of Cryptosporidium parvum by two-dimensional gel electrophoresis.

Five isolates of Cryptosporidium parvum collected from human, horse, and calf sources were compared for differences in sporozoite protein patterns by using two-dimensional gel electrophoresis. Silver-stained two-dimensional gels contained over 300 protein spots from detergent-solubilized sporozoites. A distinguishing 106-kilodalton peptide that shifted in isoelectric point was detected in four of the five isolates. Computerized two-dimensional gel analysis was performed to obtain objective quantitation of the pI shift. Three of these four isolates could be differentiated from one other by the pI shift in this peptide. The fifth isolate was distinguished by the absence of the 106-kilodalton peptide and the presence of a 40-kilodalton peptide that was not observed in any other isolate.     

Epigenetic modulation at birth – altered DNA-methylation in white blood cells after Caesarean section

Aim:  Delivery by C-section (CS) has been associated with increased risk for allergy, diabetes and leukaemia. Whereas the underlying cause is unknown, epigenetic change of the genome has been suggested as a candidate molecular mechanism for perinatal contributions to later disease risk. We hypothesized that mode of delivery affects epigenetic activity in newborn infants.
Methods:  A total of 37 newborn infants were included. Spontaneous vaginal delivery (VD) occurred in 21, and 16 infants were delivered by elective CS. Blood was sampled from the umbilical cord and 3–5 days after birth. DNA-methylation was analyzed in leucocytes.
Results:  Infants born by CS exhibited higher DNA-methylation in leucocytes compared with that of those born by VD (p < 0.001). After VD, newborn infants exhibited stable levels of DNA-methylation, as evidenced by comparing cord blood values with those 3–5 days after birth (p = 0.55). On postnatal days 3–5, DNA-methylation had decreased in the CS group (p = 0.01) and was no longer significantly different from that of VD (p = 0.10).
Conclusion:  DNA-methylation is higher in infants delivered by CS than in infants vaginally born. Although currently unknown how gene expression is affected, or whether epigenetic differences related to mode of delivery are long-lasting, our findings open a new area of clinical research with potentially important public health implications.     

The English version of the Verona medical interview classification system (VR-MICS). An assessment of its reliability and a comparative cross-cultural test of its validity

OBJECTIVE: This study aimed to assess the inter-rater and intra-rater reliability of the English translation of the original Italian version of the VR-MICS and to evaluate its sensitivity by comparing the coding of English and Italian general practice consultations with emotionally distressed and non-distressed patients, as defined by the 12-item General Health Questionnaire (GHQ-12). METHOD: Six male GPs from Manchester (UK) and six from Verona (Italy) each contributed five consultations, which were coded using the VR-MICS. Intra-rater and inter-rater reliability were assessed both for the division of interviews into speech units and the speech unit coding. Interaction and main effects of GHQ-12 status and nationality on patient and GP expressions were assessed by two-way ANOVA. RESULTS: Agreement indices for the division of speech units varied between 88-96 and 87-93% for GP and patient speech, respectively; those for coding categories between 88-91 and 82-86%, with Cohen's Kappa values between 0.86-0.91 and 0.80-0.85 for GP and patient speech, respectively. Cross-cultural comparisons of patient and GP speech showed no interaction effects between GHQ-12 status and nationality. The Italian GPs were more 'doctor-centred', while the UK GPs tended to use a more 'sharing' consulting style. Independent of nationality, distressed patients talked more, gave more psychosocial cues and increased amounts of positive talk compared to non-distressed patients. GPs in both settings, when interviewing distressed patients, reduced social conversation and increased psychosocial information-giving, checking questions and reassurance. CONCLUSION: The English translation of the VR-MICS showed satisfactory reliability indices and similar sensitivity to patients' verbal behaviours in relation to their emotional state in the two settings. PRACTICE IMPLICATIONS: The VR-MICS may be an useful coding instrument to support collaborative research on doctor-patient communication between the two countries.