Height and Weight in Osteogenesis Imperfecta: Impact of OI Type and Age in a Large Cohort

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 224-247-Osteoporosis I
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-242
Emily L. Germain-Lee*, Feng-Shu Brennen, Diana R. Stern and Jay R. Shapiro
Kennedy Krieger Institute (KKI), Baltimore, MD
Osteogenesis Imperfecta (OI) is a genetic disorder of bone and connective tissue, most commonly caused by mutations that alter synthesis of type I collagen. Impaired linear growth and short stature are salient features of OI, differing in severity based on OI type. The etiology of growth retardation is not well understood; information on weight in OI is scarce. Data have previously been limited for anthropometric parameters in patients with OI. Here we report height (Ht) and weight (Wt) data for a large cohort with different OI types. We examined 344 patients in the OI Clinic at KKI, which included 145 children and 199 adults. The largest group had type I OI (48 girls, 48 boys, 83 adult females, 45 adult males). Ht Z-scores were calculated using the standards developed by CDC/WHO based on age. Our Ht data revealed no gender differences. The children with OI type I had a mean Ht Z- score of -1.26; adult mean Ht Z-score was -1.49. A small group had OI type V (1 girl, 4 boys, 3 adult females, 6 adult males). The mean Ht Z-score in children in this group was -1.17, similar to type I OI; however, the mean adult Ht Z-score (n=9) was impaired at -4.36 (range = -1.39 to -8.89; only two with Z-scores better than -2.0). Patients with OI type IV had significantly decreased mean Ht Z-scores, as previously shown in the literature: childhood mean Ht Z-score = -3.97 (5 girls, 5 boys); adult mean Ht Z-score = -4.61 (15 females, 11 males). Finally, the mean Ht Z-score in type III OI was the most severely impaired: children = -6.49 compared to adult mean of -8.90 (22 girls, 12 boys; 20 adult females, 16 adult males).  Of note, 60% of the children in our cohort were treated with bisphosphonates. There were no significant differences between the treated and untreated groups among all OI types for Ht Z-scores. Longitudinal Ht data were obtained from patients with OI types I and III (18 girls and 18 boys with type I, 8 girls and 2 boys with type III). The growth velocities of children with type III begin to decelerate before age 5; the poor growth continued through puberty without an obvious growth spurt. In type I, the growth velocities taper near the onset of puberty. Obesity is also a concern for all patients with OI, with type III patients being the most severely affected; when taller than 100 cm, patients’ weights were significantly increased. Conclusion: Height was consistent with the severity of the OI type.  In all cases, the mean Ht Z-scores for adults were more affected than those for children. There are multiple etiologies for the disparities in childhood versus adult heights, such as recurrent fractures, worsening scoliosis, vertebral compressions, and sub-normal pubertal growth spurts.  Onset of puberty and progression through the Tanner stages were appropriate, but linear growth was not. This requires further investigation. Immobility due to fractures and worsening scoliosis augments weight increase over time and indicates a need for weight control measures.

Nothing to Disclose: ELG, FSB, DRS, JRS

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: Charitable and Research Foundation, Punta Gorda, Florida