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Hypertrophic cardiomyopathy (HCM) is a genetically heterogeneous disorder with several established genotype-phenotype relationships. While biallelic truncating variants in the ALPK3 gene cause severe congenital HCM, recent studies have associated heterozygous truncating variants (ALPK3tv) with milder adult-onset HCM. Here we describe a multicenter cohort of 21 individuals with heterozygous ALPK3tv from 10 institutions in the United States, highlighting distinctive clinical characteristics compared to a control group of 132 patients with HCM caused by deleterious variants in sarcomeric genes. As compared to other HCM genotypes, ALPK3tv patients present at an older age (mean 57.25 years) with significantly lower left ventricular wall thickness (14.09 vs 19.78 mm with echocardiogram and 16.13 vs 21.13 mm with cardiac MRI), a lower prevalence of obstructive HCM (15% of ALPK3tv vs 45% of controls), and a strikingly higher incidence of apical aneurysm (22.22% vs. 2.40% in the control group). These results suggest a milder degree of hypertrophy in heterozygous ALPK3-related HCM as compared to other Mendelian causes of HCM, although the increased occurrence of apical aneurysms could have implications for ventricular arrhythmia risk. Our study underscores the importance of recognizing heterozygous ALPK3tv as a cause of adult-onset HCM and provides a comprehensive characterization of its clinical phenotype.

Pathogenic variants in ACTA2, encoding smooth muscle α-actin, predispose to thoracic aortic aneurysms and dissections. ACTA2 variants altering arginine 179 predispose to a more severe, multisystemic disease termed smooth muscle dysfunction syndrome (SMDS; OMIM 613834). Vascular complications of SMDS include patent ductus arteriosus (PDA) or aortopulmonary window, early-onset thoracic aortic disease (TAD), moyamoya-like cerebrovascular disease, and primary pulmonary hypertension. Patients also have dysfunction of other smooth muscle-dependent systems, including congenital mydriasis, hypotonic bladder, and gut hypoperistalsis. Here, we describe five patients with novel heterozygous ACTA2 missense variants, p.Arg179Gly, p.Met46Arg, p.Thr204Ile, p.Arg39Cys, and p.Ile66Asn, who have clinical complications that align or overlap with SMDS. Patients with the ACTA2 p.Arg179Gly and p.Thr204Ile variants display classic features of SMDS. The patient with the ACTA2 p.Met46Arg variant exhibits exclusively vascular complications of SMDS, including early-onset TAD, PDA, and moyamoya-like cerebrovascular disease. The patient with the ACTA2 p.Ile66Asn variant has an unusual vascular complication, a large fusiform internal carotid artery aneurysm. The patient with the ACTA2 p.Arg39Cys variant has pulmonary, gastrointestinal, and genitourinary complications of SMDS but no vascular manifestations. Identifying pathogenic ACTA2 variants associated with features of SMDS is critical for aggressive surveillance and management of vascular and nonvascular complications and delineating the molecular pathogenesis of SMDS., (© 2022 Wiley Periodicals LLC.)

Background: Disclosure of pathogenic variants to thoracic aortic dissection biobank participants was implemented. The impact and costs, including confirmatory genetic testing in a Clinical Laboratory Improvement Amendments (CLIA)-certified laboratory, were evaluated., Methods: We exome sequenced 240 cases with thoracic aortic dissection and 258 controls, then examined 11 aortopathy genes. Pathogenic variants in 6 aortopathy genes (COL3A1, FBN1, LOX, PRKG1, SMAD3, and TGFBR2) were identified in 26 participants, representing 10.8% of the cohort (26/240). A second research sample was used to validate the initial findings. Mailed letters to participants disclosed that a potentially disease causing DNA alteration had been identified (neither the gene nor variant was disclosed). Participants were offered clinical genetic counseling and confirmatory genetic testing in a CLIA laboratory., Results: Excluding 6 participants who were deceased or lost to follow-up, 20 participants received the disclosure letter, 10 of whom proceeded with genetic counseling, confirmatory genetic testing, and enrolled in a survey study. Participants reported satisfaction with the letter (4.2 ± 0.7) and genetic counseling (4.4 ± 0.4; [out of 5, respectively]). The psychosocial impact was characterized by low decisional regret (11.5 ± 11.6) and distress (16.0 ± 4.2, [out of 100, respectively]). The average cost for 26 participants was $400, including validation and sending letters. The average cost for those who received genetic counseling and CLIA laboratory confirmation was $605., Conclusions: Participants were satisfied with the return of clinically significant biobank genetic results and CLIA laboratory testing; however, the process required significant time and resources. These findings illustrate the trade-offs involved for researchers considering returning research genetic results.

Ring chromosomes are uncommon findings in prenatal diagnosis. Growth retardation is the most significant manifestation, in particular among patients with rings of larger chromosomes. A 30-year-old gravida 1, para 0 white woman was referred for genetic counseling because of maternal anxiety. Cytogenetic analysis of amniotic fluid cells at 16 weeks gestation revealed an abnormal mosaic female chromosome complement; 46,XX,r(11)(p15q25)[14]/45,XX,-11[7]. The ring 11 showed no detectable loss of chromosomal material at 450 band level. Both parents had a normal karyotype. Fluorescence in situ hybridization demonstrated intact subtelomeric regions in the ring chromosome. A targeted ultrasound evaluation at the time of consultation suggested no significant abnormalities. The parents were counseled and subsequently decided to terminate the pregnancy. The autopsy revealed an immature female fetus with abnormal craniofacial features including brachycephaly, low-set ears and hypertelorism, bicornuate uterus, and calcifications in the renal tubules. The abnormal phenotypes could be a consequence of the ring instability, submicroscopic deletion, and/or alteration of genetic material at the site of fusion., (Copyright 2001 Wiley-Liss, Inc.)