A novel nonsense mutation in the β-subunit of the epithelial sodium channel causing Liddle syndrome

PURPOSE

Liddle syndrome is a hereditary form of arterial hypertension caused by mutations in the genes coding of the epithelial sodium channel - SCNN1A, SCNN1B and SCNN1G. It is characterised by early onset of hypertension and variable biochemical features such as hypokalaemia and low plasma concentrations of renin and aldosterone. Phenotypic variability is large and, therefore, LS is probably underdiagnosed. Our objective was to examine a family suspected from Liddle syndrome including genetic testing and evaluate clinical and biochemical features of affected family members.

MATERIALS AND METHODS

Thirteen probands from the Czech family, related by blood, underwent physical examination, laboratory tests, and genetic testing. Alleles of SCNN1B and SCNN1G genes were examined by PCR amplification and Sanger sequencing of amplicons.

RESULTS

We identified a novel mutation in the β-subunit of an epithelial sodium channel coded by the SCNN1B gene, causing the nonsense mutation in the protein sequence p.Tyr604*. This mutation was detected in 7 members of the family. The mutation carriers differed in the severity of hypertension and hypokalaemia which appeared only after diuretics in most of them; low aldosterone level (< 0.12 nmol/l) was, however, present in all.

CONCLUSIONS

This finding expands the spectrum of known mutations causing Liddle syndrome. Hypoaldosteronemia was 100% sensitive sign in the mutation carriers. Low levels are observed especially in the Caucasian population reaching 96% sensitivity. Assessment of plasma aldosterone concentration is helpful for differential diagnosis of arterial hypertension.

CONDENSED ABSTRACT

Liddle syndrome is a hereditary form of arterial hypertension caused by mutations in the genes encoding the epithelial sodium channel's α-, β- and γ-subunit. It is usually manifested by early onset of hypertension accompanied by low potassium and aldosterone levels. We performed a physical examination, laboratory tests and genetic screening in 13 members of a Czech family. We found a new mutation of the SCNN1B gene which encodes the β-subunit of the epithelial sodium channel. We describe the variability of each family member phenotype and point out the relevance of using aldosterone levels as a high sensitivity marker of Liddle syndrome in Caucasians.

The effects of intrapartum synthetic oxytocin on maternal postpartum mood: findings from a prospective observational study

Postpartum depression (PPD) affects up to 19% of all mothers, with detrimental effects on both mother and child. The antidepressant and anxiolytic effects of plasma oxytocin are well-documented, but it is still disputable whether synthetic oxytocin (synOT) may protect women against postpartum mood alterations. The current study examined the association between synOT intrapartum and maternal mood postpartum using a prospective design. Two hundred sixty women were screened for depressive symptoms in the last trimester of pregnancy and then again 6 weeks and 9 months postpartum using the Edinburgh Postnatal Depression Scale. They also completed Maternity Blues Questionnaire in the first postpartum week. The data concerning the intrapartum interventions and health status of the newborn were extracted from the medical records. Cox proportional hazards regression adjusted for a history of depression, mode of delivery, and childbirth experience showed that synOT predicted a significantly lower risk of PPD (HR = 0.65, 95% CI 0.45-0.95, p = 0.025). The risk factors for PPD included a history of depression (HR = 3.20, 95% CI 2.33-4.40, p < 0.001) and negative childbirth experience (HR = 1.39, 95% CI 1.01-1.90, p = 0.040). Logistic regression adjusted for the same covariates found no significant effect of synOT on maternity blues (OR = 0.64, 95% CI 0.31-1.32, p = 0.23). While synOT administered intrapartum does not affect maternal mood immediately, it may come to effect some weeks after childbirth to protect mothers from developing PPD symptoms.

[Risk factors for cardiovascular diseases in the descendants of patients after early myocardial infarction]

GOAL

The cardiovascular diseases (CVDs) developing as the result of atherosclerosis are among the most frequent causes of morbidity and mortality within the Czech Republic and elsewhere. Genetic predisposition for cardiovascular diseases is amplified in the presence of routine risk factors which can be influenced. Our aim was to establish whether the level of the risk factors for ICHS already differs in the population of healthy descendants of the patients after early myocardial infarction, as opposed to the control group of examined individuals.

METHODOLOGY

We approached adult children (n = 127; age 28.7 ± 6.5 years) of the patients with early manifestation of ICHS, who were examined within the study EUROASPIRE IV. The examination of both the descendants and the control group (n = 199; age 28.9 ± 5.3 years) focused on identifying the risk factors for ICHS.

RESULTS

Descendants presented arterial hypertension more often (18.9 vs 8.0 %, p = 0.003) and there were more smokers among them compared to the control group (37 vs 24.1 %, p = 0.01). The levels of triglycerides (1.13 vs 0.99 mmol/l, p = 0.05) and LDL-cholesterol (2.7 vs 2.45 mmol/l, p = 0.01) were higher in the descendant group, HDL-cholesterol was similar in both groups (1.6 vs 1.67 mmol/l, p = 0.17). Increased fasting glycemia occurred more frequent in the descendant group (5.5 vs 1.5 %, p = 0.05). None of the examined participants met the criteria for the diagnosis of diabetes mellitus. Aortic stiffness was higher in the descendant group as opposed to the control group (6.2 vs 5.8 m/s, p = 0.001). The total calculated cardiovascular risk based on the SCORE system was also higher in the descendant group as compared to the control group - the current risk related to the age of 40 years: 0.35 (0.19-0.64) vs 0.20 (0.13-0.47), p < 0.0001 and the risk related to the age of 60 years: 3.35 (2.23-5.36) vs 2.40 (1.58-4.11), p < 0.0001.

CONCLUSION

The population of the descendants includes, based on our results, a greater number of smokers and hypertensive patients. They also have higher levels of LDL-cholesterol, triglycerides and impaired fasting glycemia more frequently. Unfavourable genetic predisposition along with unfitting lifestyle contributes to a higher likelihood of accumulation of risk factors, and therefore to a higher risk of a cardiovascular disease manifestation. In practice we should try, with regard to these predisposed individuals, to lower their cardiovascular risk and implement a healthy lifestyle.Key words: atherosclerosis - cardiovascular disease - lifestyle - myocardial infarction - primary prevention - risk factors for CVD.

Differential effect of metabolic syndrome on various parameters of arterial stiffness

Metabolic syndrome (MetSy) is associated with a high risk of cardiovascular complications. Arterial stiffness is an independent predictor of cardiovascular morbidity and mortality. This study investigated the effect of individual MetSy risk factors on central and peripheral parameters of aortic stiffness. In the Czech post-MONICA study, we measured aortic pulse-wave velocity (aPWV), lower extremity pulse-wave velocity (lePWV), augmentation index (AIx) and central augmentation pressure (cAP) in 936 subjects. Based on the definition of MetSy, we divided subjects according to number of risk factors. We used univariate and multivariate linear regression analysis to assess the association between number of risk factors and aPWV, lePWV, AIx and cAP. In analyses adjusted for age, gender, heart rate and mean arterial pressure, aPWV was higher in subjects with MetSy (MetSy+ group) than in those without (MetSy + group) (8.3 vs. 7.7 m/s; p < 0.0001), but lePWV was not significantly different between the groups (11.0 vs. 11.2 m/s; p = 0.2037). After adjustment for covariates, AIx in MetSy+ was lower than in MetSy- respondents (143.2 vs. 146.8; p = 0.014). In adjusted analysis, aPWV rose with increasing number of MetSy risk factors (7.3 ± 0.1 vs. 9.0 ± 0.1 m/s; p for trend < 0.0001). The number of MetSy risk factors did not affect lePWV (p = 0.11). AIx decreased with higher number of MetSy risk factors (148.3 vs. 141.5; p = 0.020). This finding confirms the fact that PWV and AIx may have different associations with risk factors and AIx should not be used as an isolated parameter of arterial stiffness. The individual MetSy risk factors have only a small effect on lower extremity arterial stiffness.

Social psychological predictors of satisfaction with intrapartum and postpartum care - what matters to women in Czech maternity hospitals?

OBJECTIVE

To identify the social psychological factors affecting women's evaluation of care provided in Czech maternity hospitals using following criteria: satisfaction with intrapartum and postpartum care, willingness to return to a given hospital and to recommend the hospital to others.

METHODS

762 women completed a 71-item original Czech questionnaire KLI-P designed to measure the psychosocial climate in both delivery and after-birth unit on six scales. The sample was representative of the Czech parturients population. Multivariate logistic regression was used to investigate the predictive value of the questionnaire scales for maternal satisfaction, willingness to return to and to recommend a given hospital.

RESULTS

For delivery unit, the satisfaction predictors were: helpfulness and empathy of midwives (Χ²=48.9), communication of information and availability of caregivers (Χ²=16.6), helpfulness and empathy of physicians (Χ²=10.9), symmetrical and respectful attitude of staff members (Χ²=9.7) and physical comfort and services (Χ²=7.6). The predictors of satisfaction with after-birth unit included helpfulness and empathy of the staff (Χ²≥42.1), communication of information and availability of caregivers (Χ²=52.5), physical comfort and services (Χ²=30.6), control and involvement in decision-making (Χ²=6.6) and parity (Χ²=8.6). The factors influencing women's willingness to return to and to recommend a hospital differed from the predictors of general satisfaction.

CONCLUSIONS

The satisfaction factors revealed in this research correspond predominantly to the results of studies conducted in other countries (warm, non-formal and supportive approach, sufficient and well-timed provision of information and explanation, availability of caregivers, physical environment). However, participation in decision making, which has been repeatedly shown to be among the strongest predictors of childbirth satisfaction, was not important for the Czech parturients' satisfaction with intrapartal care. This finding can be explained by different attitudes and expectations of both parturients and caregivers in a post-totalitarian country.