Genetic variations in PTPN11 lead to a recurrent Left Ventricular Outflow Tract Obstruction phenotype in childhood hypertrophic cardiomyopathy

Objective Left ventricular septal myotomy provides a favorable prognosis for children with hypertrophic obstructive cardiomyopathy (HOCM). However, some children still suffer from recurrent left ventricular outflow tract obstruction (LVOTO) after surgery. Poor prognosis exists for HOCM caused by PTPN11 mutation. Therefore, the aim of this study was to determine the clinical features of recurrent obstruction in children with HOCM caused by pathogenic mutations in the PTPN11 gene. Methods A total of 56 children were diagnosed with HOCM underwent septal myectomies. Whole exome sequencing of 49 pediatric cardiomyopathies associated genes (including PTPN11) were performed. We performed hematoxylin-eosin(H&E), Masson, and wheat germ agglutinin (WGA)staining of tissues positive for PTPN11 and those negative for PTPN11 were conducted. Results Whole exome sequencing results showed 11 PTPN11 mutation (19.6%) children. In long-term follow-up (median 37 months, maximum 9 years), children with PTPN11 mutation had 6(54.5%) recurrent LVOTO compared with other groups (P=.015), but similar survival rates(P=.514). The mean postoperative time to recurrent obstruction was 22 ± 27 months. Children with PTPN11 mutation were 9-fold more likely to experience the risk associated with recurrent obstruction (95% CI = 1.77-45.81, P < .001). H&E, Masson and WGA staining also revealed more cardiomyocyte hypertrophy in PTPN11 mutation tissues. See Figure 4 for a graphical abstract of the study. Conclusion Children with PTPN11 mutation-associated hypertrophic cardiomyopathy have a higher risk of recurrent LVOTO.