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Published on: December 16, 2022
Case Series of 6 Fetuses With Osteogenesis Imperfecta Type II: A Retrospective Study of Heart Pathology
Sara J E Verdonk1,2,3, Silvia Storoni1,2,3, Lidiia Zhytnik2,3,4,5,6
1Department of Endocrinology and Metabolism, Amsterdam University Medical Center, Amsterdam, The Netherlands.
Insights
Osteogenesis imperfecta (OI) type II fetuses show normal collagen type I expression in the heart without structural anomalies. This suggests collagen defects may not cause early heart issues but could increase later-life degeneration risk.
Area of Science:
- Genetics
- Pathology
- Developmental Biology
Background:
- Osteogenesis imperfecta (OI) is a rare genetic disorder causing bone fragility.
- Skeletal issues in OI are well-known, but fetal cardiac effects are understudied.
Purpose of the Study:
- To investigate cardiac pathology in fetuses with Osteogenesis Imperfecta type II.
- To determine the role of collagen type I in fetal heart development in OI.
Main Methods:
- Retrospective case series of 6 genetically confirmed OI type II fetuses.
- Analysis of medical records and autopsy reports.
- Immunohistochemistry to examine collagen type I expression in fetal hearts.
Main Results:
- Robust collagen type I expression was confirmed in all fetal hearts.
- No structural heart anomalies were observed in any of the fetuses.
- Heart weight was normal in five fetuses; one showed low weight due to growth retardation.
Conclusions:
- Collagen type I abnormalities do not appear to cause heart anomalies in early OI type II development.
- The impact of collagen defects might relate to increased susceptibility to later degenerative changes.
Introduction:
Osteogenesis imperfecta (OI) is a rare genetic disorder characterized by bone fragility. While skeletal manifestations are well documented, few studies have explored the effect of OI on the fetal heart. This retrospective case series investigates cardiac pathology in OI type II fetuses, aiming to address this gap.
Methods:
Medical records and autopsy reports of 6 genetically confirmed OI type II cases were examined. Fetuses had pathogenic variants in COL1A1 or PPIB, inducing structural defects in collagen type I. In addition to hematoxylin and eosin and Elastic van Gieson staining, the expression of collagen type I, COL1A1 and COL1A2 chains was examined by immunohistochemistry.
Results:
Immunohistochemistry confirmed robust expression of collagen type I throughout the heart. Five fetuses had normal heart weight, while 1 had a low heart weight in the context of generalized growth retardation. None displayed structural heart anomalies.
Conclusion:
This study reveals robust collagen type I expression in the hearts of OI type II fetuses without structural anomalies. We hypothesize that collagen type I abnormalities may not be causative factors for heart anomalies during early embryonic development. Instead, their impact may be conceivably related to an increased susceptibility to degenerative changes later in life.
