Xue Gong1, Peiyu Yu1,2, Ting Wu3, Yunru He1, Kaiyu Zhou1, Yimin Hua1, Sha Lin1, Tao Wang1, He Huang4, Yifei Li1. 1. Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China. 2. Department of Pediatrics, Chengdu Shangjin Nanfu Hospital, Chengdu, China. 3. Department of Ultrasonic Medicine, West China Second University Hospital, Sichuan University, Chengdu, China. 4. Department of Echocardiography, West China Hospital, Sichuan University, Chengdu, China.
Abstract
BACKGROUND: PRKAG2 cardiac syndrome is a rare autosomal dominant genetic disorder caused by a PRKAG2 gene variant. There are several major adverse cardiac presentations, including hypertrophic cardiomyopathy (HCM) and life-threatening arrhythmia. Two cases with pathogenic variants in the PRKAG2 gene are reported here who presents different cardiac phenotypes. METHODS: Exome sequencing and variant analysis of PRKAG2 were performed to obtain genetic data, and clinical characteristics were determined. RESULTS: The first proband was a 9-month-old female infant (Case 1), and was identified with severe DCM and resistant heart failure. The second proband was a 10-year-old female infant (Case 2), and presented with HCM and ventricular preexcitation. Exome sequencing identified a de novo c.425C > T (p.T142I) heterozygous variant in the PRKAG2 gene for Case 1, and a c.869A > T (p.K290I) for Case 2. The mutated sites in the protein were labeled and identified as p.K290 in the CBS domain and p.T142 in the non-CBS domain. Differences in the molecular functions of CBS and non-CBS domains have not been resolved, and variants might lead to the different cardiomyopathy phenotypes. Single-cell RNA analysis demonstrated similar expression levels of PRKAG2 in cardiomyocytes and conductive tissues. These results suggest that the arrhythmia induced by the PRKAG2 variant was the primary change, and not secondary to cardiomyopathy. CONCLUSION: In summary, this is the first case report to describe a DCM phenotype with early onset in patients possessing a PRKAG2 c.425C > T (p.T142I) pathogenic variant. Our results aid in understanding the molecular function of non-CBS variants in terms of the disordered sequence of transcripts. Moreover, we used scRNA-seq to show that electrically conductive cells express a higher level of PRKAG2 than do cardiomyocytes. Therefore, variants in PRKAG2 are expected to also alter the biological function of the conduction system.
BACKGROUND: PRKAG2 cardiac syndrome is a rare autosomal dominant genetic disorder caused by a PRKAG2 gene variant. There are several major adverse cardiac presentations, including hypertrophic cardiomyopathy (HCM) and life-threatening arrhythmia. Two cases with pathogenic variants in the PRKAG2 gene are reported here who presents different cardiac phenotypes. METHODS: Exome sequencing and variant analysis of PRKAG2 were performed to obtain genetic data, and clinical characteristics were determined. RESULTS: The first proband was a 9-month-old female infant (Case 1), and was identified with severe DCM and resistant heart failure. The second proband was a 10-year-old female infant (Case 2), and presented with HCM and ventricular preexcitation. Exome sequencing identified a de novo c.425C > T (p.T142I) heterozygous variant in the PRKAG2 gene for Case 1, and a c.869A > T (p.K290I) for Case 2. The mutated sites in the protein were labeled and identified as p.K290 in the CBS domain and p.T142 in the non-CBS domain. Differences in the molecular functions of CBS and non-CBS domains have not been resolved, and variants might lead to the different cardiomyopathy phenotypes. Single-cell RNA analysis demonstrated similar expression levels of PRKAG2 in cardiomyocytes and conductive tissues. These results suggest that the arrhythmia induced by the PRKAG2 variant was the primary change, and not secondary to cardiomyopathy. CONCLUSION: In summary, this is the first case report to describe a DCM phenotype with early onset in patients possessing a PRKAG2 c.425C > T (p.T142I) pathogenic variant. Our results aid in understanding the molecular function of non-CBS variants in terms of the disordered sequence of transcripts. Moreover, we used scRNA-seq to show that electrically conductive cells express a higher level of PRKAG2 than do cardiomyocytes. Therefore, variants in PRKAG2 are expected to also alter the biological function of the conduction system.
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