<abstract xmlns="http://www.w3.org/1999/xhtml">Introduction. Osteogenesis imperfecta (OI) is etiologically heterogeneous disorder characterized by childhood osteoporosis. A subtype OI type V is caused by the same c.-14C>T mutation in the IFITM5 gene. Nevertheless, there is a marked interindividual phenotypic variability in clinical presentation; however, response to bisphosphonates is reported to be good. Methods. Two individuals with OI type V had multiple recurrent fractures with hypertrophic calluses, scoliosis and ossifications of the forearm interosseous membranes. Sequencing of IFITM5, genotyping of variants rs2297480 in farnesyl diphosphate synthase gene (FDPS), and rs3840452 in geranylgeranyl diphosphate synthase 1 gene (GGPS1), both involved in bisphosphonate metabolism, was performed. Results. In patient 1 BMD reached normal values during bisphosphonate treatment and remained normal four years after the treatment discontinuation. In patient 2 no increase in BMD after five years of bisphosphonate treatment was observed and callus formation continued. The c.-14C>T IFITM5 mutation in heterozygous state was detected in both individuals. Additionally, both patients carried FDPS variant rs2297480 in homozygous state, and were heterozygous for GGPS 1 variant rs3840452. Conclusions. The paper presents a short overview of childhood osteoporosis with a special emphasis on OI type V by presenting two cases. Both OI type V patients had identical disease-causing mutation, but marked interindividual phenotypic variability. The striking failure in response to bisphosphonate treatment in one of the patients could not be explained by the variants in genes involved in bisphosphonate metabolism.</abstract>

Introduction. Osteogenesis imperfecta (OI) is etiologically heterogeneous disorder characterized by childhood osteoporosis. A subtype OI type V is caused by the same c.-14C>T mutation in the IFITM5 gene. Nevertheless, there is a marked interindividual phenotypic variability in clinical presentation; however, response to bisphosphonates is reported to be good. Methods. Two individuals with OI type V had multiple recurrent fractures with hypertrophic calluses, scoliosis and ossifications of the forearm interosseous membranes. Sequencing of IFITM5, genotyping of variants rs2297480 in farnesyl diphosphate synthase gene (FDPS), and rs3840452 in geranylgeranyl diphosphate synthase 1 gene (GGPS1), both involved in bisphosphonate metabolism, was performed. Results. In patient 1 BMD reached normal values during bisphosphonate treatment and remained normal four years after the treatment discontinuation. In patient 2 no increase in BMD after five years of bisphosphonate treatment was observed and callus formation continued. The c.-14C>T IFITM5 mutation in heterozygous state was detected in both individuals. Additionally, both patients carried FDPS variant rs2297480 in homozygous state, and were heterozygous for GGPS 1 variant rs3840452. Conclusions. The paper presents a short overview of childhood osteoporosis with a special emphasis on OI type V by presenting two cases. Both OI type V patients had identical disease-causing mutation, but marked interindividual phenotypic variability. The striking failure in response to bisphosphonate treatment in one of the patients could not be explained by the variants in genes involved in bisphosphonate metabolism.

Childhood Osteoporosis and Presentation of Two Cases with Osteogenesis Imperfecta Type V / Osteoporoza V Otroški Dobi in Predstavitev Dveh Bolnikov Z Osteogenesis Imperfecta Tipa V

University Children’s Hospital, Department of Pediatric Endocrinology, Diabetes and Metabolic Diseases, Bohoriceva 20, 1000 Ljubljana, Slovenia

University Medical Centre Ljubljana, University Children’s Hospital, Unit for Special Laboratory Diagnostics, Vrazov trg 1, 1000 Ljubljana, Slovenia

University of Ljubljana, Faculty of Medicine, Vrazov trg 2, 1000 Ljubljana, Slovenia

University of Ljubljana, Faculty of Farmacy, Askerceva 7, 1000 Ljubljana, Slovenia

Slovenian Journal of Public Health

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Introduction. Osteogenesis imperfecta (OI) is etiologically heterogeneous disorder characterized by childhood osteoporosis. A subtype OI type V is caused by...

Childhood Osteoporosis and Presentation of Two Cases with Osteogenesis Imperfecta Type V / Osteoporoza V Otroški Dobi in Predstavitev Dveh Bolnikov Z Osteogenesis Imperfecta Tipa V

Published Online: Mar 13, 2015

Page range: 119 - 125

Received: Dec 16, 2014

Accepted: Feb 03, 2015

DOI: https://doi.org/10.1515/sjph-2015-0018

© National Institute of Public Health, Slovenia

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.