👤 Galit Tal

Few studies describe the impact of rapid exome sequencing (ES) on pediatric cardiomyopathy in urgent clinical settings. Here, we retrospectively report the impact of rapid singleton ES in pediatric patients presented with acute heart failure and isolated cardiomyopathy or myocarditis, between 2021 and 2023 at a single tertiary care center. A total of nine patients were included; age range: 5 days-11 years (median 42 days). Eight patients (88.8%) presented in the first year of life. The turnaround time for the ES results was 5-14 days (median 9 days). The diagnostic yield was 5/9 (55.5%), confirming primary cardiomyopathy. The majority had dominant disorders (ACTC1, MYBCP3, TNNI3, and NKX2-5), with two (22.2%) occurring de novo. One patient had a recessive condition (MYBPC3). In three patients (33.3%) who rapidly deteriorated during hospitalization, ES results had a major impact on immediate medical management. In most patients, the diagnosis led to the avoidance of further metabolic workup, cardiac magnetic imaging and vitamin treatment. In two families with no prior history of cardiomyopathy, at-risk relatives were advised to initiate cardiac surveillance. Overall the results show high clinical impact due to a shorter time to diagnosis, a high diagnostic yield, an improved therapeutic approach, in addition to the facilitation of genetic counseling for family planning and cascade testing of relatives at risk. Show less

Post-transcriptional regulatory processes may change transcript levels and affect cell-to-cell variability or noise. We study small-RNA downregulation to elucidate its effects on noise in the iron homeostasis network of Escherichia coli In this network, the small-RNA RyhB undergoes stoichiometric degradation with the transcripts of target genes in response to iron stress. Using single-molecule fluorescence in situ hybridization, we measured transcript numbers of the RyhB-regulated genes sodB and fumA in individual cells as a function of iron deprivation. We observed a monotonic increase of noise with iron stress but no evidence of theoretically predicted, enhanced stoichiometric fluctuations in transcript numbers, nor of bistable behavior in transcript distributions. Direct detection of RyhB in individual cells shows that its noise is much smaller than that of these two targets, when RyhB production is significant. A generalized two-state model of bursty transcription that neglects RyhB fluctuations describes quantitatively the dependence of noise and transcript distributions on iron deprivation, enabling extraction of in vivo RyhB-mediated transcript degradation rates. The transcripts' threshold-linear behavior indicates that the effective in vivo interaction strength between RyhB and its two target transcripts is comparable. Strikingly, the bacterial cell response exhibits Fur-dependent, switch-like activation instead of a graded response to iron deprivation. Show less