Lamin A/C-Related Cardiac Disease: Late Onset With a Variable and Mild Phenotype in a Large Cohort of Patients With the Lamin A/C p.(Arg331Gln) Founder Mutation

BACKGROUND

Interpretation of missense variants can be especially difficult when the variant is also found in control populations. This is what we encountered for the LMNA c.992G>A (p.(Arg331Gln)) variant. Therefore, to evaluate the effect of this variant, we combined an evaluation of clinical data with functional experiments and morphological studies.

METHODS AND RESULTS

Clinical data of 23 probands and 35 family members carrying this variant were retrospectively collected. A time-to-event analysis was performed to compare the course of the disease with carriers of other LMNA mutations. Myocardial biopsies were studied with electron microscopy and by measuring force development of the sarcomeres. Morphology of the nuclear envelope was assessed with immunofluorescence on cultured fibroblasts. The phenotype in probands and family members was characterized by atrioventricular conduction disturbances (61% and 44%, respectively), supraventricular arrhythmias (69% and 52%, respectively), and dilated cardiomyopathy (74% and 14%, respectively). LMNA p.(Arg331Gln) carriers had a significantly better outcome regarding the composite end point (malignant ventricular arrhythmias, end-stage heart failure, or death) compared with carriers of other pathogenic LMNA mutations. A shared haplotype of 1 Mb around LMNA suggested a common founder. The combined logarithm of the odds score was 3.46. Force development in membrane-permeabilized cardiomyocytes was reduced because of decreased myofibril density. Structural nuclear LMNA-associated envelope abnormalities, that is, blebs, were confirmed by electron microscopy and immunofluorescence microscopy.

CONCLUSIONS

Clinical, morphological, functional, haplotype, and segregation data all indicate that LMNA p.(Arg331Gln) is a pathogenic founder mutation with a phenotype reminiscent of other LMNA mutations but with a more benign course.

Quality of life in depression: daily life determinants and variability

Identifying daily influences on subjective well-being can be helpful in understanding the burden of depression. This study used experience sampling methodology (ESM) to examine the contribution of mood states, physical complaints and enjoyment of activities to a momentary measure of quality of life (mQoL), assessed by responses to the question 'In general, how is it going with you right now?' Sixty-three depressed and 22 healthy control subjects completed ESM self-reports during daily activities, 10 times per day for 6 days. In comparison to control subjects, depressed subjects had lower levels of mQoL, positive mood, and enjoyment of activity, higher negative mood, and more frequent and severe complaints. Depressed subjects were more likely than control subjects to be doing nothing and less likely to be engaged in work. Multilevel regression analysis showed that positive mood and enjoyment of the current activity were associated with higher mQoL, whereas negative mood and complaints were associated with lower mQoL. In depressed subjects, mQoL was more variable over time than in control subjects. In contrast to the ESM results, only negative mood and depression were significant predictors of global measures of QoL. We conclude that QoL has important situational determinants that can in part explain the impact of depression on daily functioning and well-being.

Changes in daily life experience associated with clinical improvement in depression

Changes in depressed outpatients' experience of daily activities after 6 weeks of antidepressant treatment were assessed with the experience sampling method (ESM). On the sickness impact profile, treatment responders (HAM-D < or = 7, n = 12) improved more than nonresponders (n = 9) in the domains of household chores, leisure and social activities. On ESM measures completed 10 x each day for 6 days pre- and posttreatment, responders showed greater increases in time spent in chores and greater decreases in passive leisure time than nonresponders. Responders showed greater increases in positive affect and greater decreases in negative affect during all activities. Thus, ESM provides quantitative evidence of changes in real life time use and subjective experience accompanying clinical improvement.