Related Experiment Video
Updated: May 13, 2026
Investigating the Pathogenesis of MYH7 Mutation Gly823Glu in Familial Hypertrophic Cardiomyopathy using a Mouse Model
Published on: August 8, 2022
Cardiac Ultrasound Findings in Infants with Severe (Hurler Phenotype) Untreated Mucopolysaccharidosis (MPS) Type I
L Schroeder1, P Orchard, C B Whitley
1Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA.
Insights
Cardiac valve thickening and aortic root dilation are common in infants with severe mucopolysaccharidosis type I (MPS I). Early detection and intervention may reduce the severity of cardiac complications in these infants.
Area of Science:
- Pediatric Cardiology
- Rare Genetic Disorders
- Biochemical Genetics
Background:
- Severe mucopolysaccharidosis type I (MPS I) is associated with cardiac valve disease and left ventricular hypertrophy in older children.
- Cardiac findings in infants with severe MPS I have not been previously reported.
- Early intervention is assumed to prevent cardiac complications, but evidence in infants is lacking.
Purpose of the Study:
- To evaluate cardiac findings in infants under one year of age with severe mucopolysaccharidosis type I.
- To assess the presence and severity of cardiac valve abnormalities and left ventricular hypertrophy in this population.
- To inform the potential benefits of early intervention strategies.
Main Methods:
- Retrospective review of echocardiograms from 13 untreated infants (<1 year) with severe MPS I.
- Analysis of left ventricular dimensions, wall thickness, systolic function, and aortic sinus diameters.
- Evaluation of mitral and aortic valves for thickening, regurgitation, and stenosis.
Main Results:
- All infants exhibited mitral valve thickening; 9/13 had mitral regurgitation (3 significant).
- 10/13 infants had aortic valve thickening; no significant aortic regurgitation or stenosis was observed.
- Left ventricular dilation (3/13) and increased wall thickness (2/13) were noted in a subset of infants; aortic root dilation occurred in 5/13.
Conclusions:
- Characteristic cardiac features of severe MPS I are present in infancy, including universal mitral and aortic valve thickening.
- While cardiac abnormalities exist, they appear less severe in infants compared to older children with MPS I.
- Findings support the potential benefit of early intervention, possibly starting with neonatal screening, to mitigate cardiac manifestations.
Background:
Serious cardiac valve disease and left ventricular hypertrophy occur in most untreated older children with severe mucopolysaccharidosis type I. Although it is assumed that early intervention prevents these processes, evaluation of cardiac findings in these infants has not yet been reported.
Methods:
We reviewed echocardiograms of 13 untreated infants < 1 year of age with severe mucopolysaccharidosis type I who had undergone evaluation for hematopoietic cell transplantation. We recorded left ventricular chamber dimensions, septal and posterior wall thicknesses, ventricular function, and aortic sinus diameters. We evaluated mitral and aortic valves for increased thickness, regurgitation, and stenosis.
Results:
Average age (7M, 6F) was 221 (range 25-347) days. Left ventricular chamber dimension was ≥2 SD of normal in 3/13; wall thicknesses were ≥2 SD of normal in 2/13 infants. Systolic function was normal. Mitral valves were thickened in all infants; mitral regurgitation was present in 9/13, but significant in only three infants. Aortic valves were thickened in 10/13, but no infant had significant aortic regurgitation. Neither mitral nor aortic stenosis occurred. Aortic roots were dilated to ≥2 SD of normal in 5/13.
Conclusions:
Characteristic cardiac features of severe mucopolysaccharidosis type I can be seen in infancy. Mitral and aortic valve thickening are nearly universally present, even in the youngest infants. In 20-30 % of infants, other abnormalities such as left ventricular dilation, increased wall thickness, and mild mitral/aortic regurgitation may occur. Aortic root dilation is a frequent finding. Early intervention with enzyme replacement therapy may minimize the incidence and severity of cardiac findings in these infants.
Summary:
Serious cardiac valve disease and left ventricular hypertrophy occur in most untreated older children with severe mucopolysaccharidosis type I. Although it is assumed that early intervention prevents these processes, evaluation of cardiac findings in these infants has not yet been reported. In our study of 13 infants with severe untreated MPS I < 1 year of age, mitral and aortic valve thickening was nearly universally present and aortic root dilation was frequent. Despite this, we found a lower incidence of left ventricular hypertrophy and both a lower incidence and milder expression of mitral and aortic valve dysfunction than previously reported in older children. These findings suggest that earlier intervention, including neonatal screening, may be of benefit to children with severe MPS I.
Related Concept Videos
01:29Cardiomyopathy III: Hypertrophic Cardiomyopathy
01:23Mitral Stenosis II: Clinical features and Diagnostic Tests
01:27Mitral Valve Prolapse I: Introduction
01:25Cardiovascular System Abnormal Findings II: Auscultation
Abnormal Heart Sounds
Gallops:
01:22Mitral Stenosis I: Introduction
01:22Lysosomal Hydrolases