Growth and Growth Hormone Use in Osteogenesis Imperfecta

One of the most striking features of moderate to severe osteogenesis imperfecta (OI) is impaired linear growth. In fact, even in mild OI, there are often signs of growth retardation. The heights of patients in all OI types are compromised compared to the heights of unaffected family members, thereby suggesting that the collagen defect per se plays a role in the impaired growth. In addition, the severity of the growth impairment correlates with the severity of the OI in general. The etiology of growth retardation in patients with OI is not completely understood. In general the poor growth in OI appears to be more notable in patients with qualitative collagen defects than in those patients with quantitative defects, thereby making the examination of growth in children with OI an important area for translational studies for genotype-phenotype correlations. Investigations of the genotype-phenotype correlations over the past several years have provided an important avenue through which an understanding of linear growth in OI may even be determined at the molecular and cellular level. The use of recombinant growth hormone (rGH) in the treatment of impaired linear growth in OI has been preliminarily investigated, both alone and in combination with bisphosphonates. Longer, properly controlled treatment trials involving more patients are warranted in order to draw generalized conclusions regarding the effects of rGH use in patients with OI. The data, however, do present a possible case for the importance of selection of patients for rGH treatment based on molecular and biochemical studies, and thus reinforce the need for a translational approach to the future of rGH treatment in OI. Further investigations on the effects on final height as well as the long-term benefits and safety of growth hormone in OI will be important in determining the use of this treatment for the growth retardation that is such a salient feature of this condition.