Osteogenesis imperfecta in a family with a novel variant in the COL1A1 gene and gonadal mosaicism: a clinical case
https://doi.org/10.20538/1682-0363-2026-1-197-201
Abstract
Osteogenesis imperfecta (OI) is a clinically heterogeneous genetic disorder whose primary clinical manifestations include susceptibility to recurrent pathological fractures and progressive skeletal deformities. In clinical practice, cases are observed where the proband’s parents show no overt signs of the disease despite having multiple affected children. This may suggest gonadal mosaicism – a condition in which the causative variant is present only in a subset of parent’s germ cells.
Gonadal mosaicism remains an understudied inheritance mechanism in monogenic diseases, complicating genetic counseling and reproductive risk assessment. In OI, this phenomenon may account for sporadic cases or recurrent births of affected children to clinically healthy parents.
This article presents a case report of a family in which the proband and his younger sister were diagnosed with COL1A1-associated OI, while the parents and other children showed no disease manifestations. Based on clinical and genetic data, the likelihood of gonadal mosaicism in one parent is discussed, along with considerations for differential diagnosis, patient management strategies, and family genetic counseling.
This case highlights the importance of molecular genetic testing not only for the probands but also for their parents to clarify the inheritance mechanism and predict the risks of disease recurrence in the family.
About the Authors
K. G. Zabudskaya
N.P. Bochkov Research Center for Medical Genetics
Russian Federation
Russian Federation
1 Moskvorechye St., 115522 Moscow, Russian Federation
A. E. Voskanyan
N.P. Bochkov Research Center for Medical Genetics
Russian Federation
Russian Federation
1 Moskvorechye St., 115522 Moscow, Russian Federation
R. G. Kuramagomedova
Vetlishchev Research and Clinical Institute of Pediatrics and Pediatric Surgery, N.I. Pirogov Russian National Research Medical University
Russian Federation
Russian Federation
2 Taldomskaya St., 125412 Moscow, Russian Federation
O. P. Ryzhkova
N.P. Bochkov Research Center for Medical Genetics
Russian Federation
Russian Federation
1 Moskvorechye St., 115522 Moscow, Russian Federation
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Review
For citations:
Zabudskaya K.G., Voskanyan A.E., Kuramagomedova R.G., Ryzhkova O.P. Osteogenesis imperfecta in a family with a novel variant in the COL1A1 gene and gonadal mosaicism: a clinical case. Bulletin of Siberian Medicine. 2026;25(1):197-201. https://doi.org/10.20538/1682-0363-2026-1-197-201
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