The prevalence of mitochondrial mutations associated with aminoglycoside-induced sensorineural hearing loss in an NICU population.

Several mitochondrial DNA variants increase risk for developing sensorineural hearing loss following exposure to aminoglycoside antibiotics, a particular concern in the premature infant population, as many of these babies spend time in neonatal intensive care units and are treated with aminoglycosides. To determine the relative prevalence of five mitochondrial DNA variants in the 12S rRNA gene, MT-RNR1, we genotyped 703 neonatal intensive care unit patients and 1473 individuals from the general Iowa population. We found that the aggregate frequency of these variants (∼1.8%) was comparable between populations. Although no hearing loss was detected by newborn hearing screens in the at-risk patients, these neonatal intensive care unit graduates have an increased life-time risk for developing aminoglycoside-induced deafness.

Intravenous bisphosphonate therapy in children with osteogenesis imperfecta.

OBJECTIVE: Several studies have reported beneficial effects of bisphosphonates in children with osteogenesis imperfecta (OI); however, these studies have differed in the protocols they used, and none has been independently replicated. We intended to confirm the efficacy of a specific intravenous bisphosphonate protocol in children with moderate to severe OI. METHODS: We used the protocol described by Glorieux et al and performed a prospective clinical trial in 6 children who were aged 22 months to 14 years. Each patient received intravenous pamidronate therapy for a minimum of 2 years in cycles of 1 mg/kg daily over 3 consecutive days at a mean cycle interval of 3.8 months. Outcome measures included lumbar spine areal bone mineral density (BMD) and z score, fracture rate, and occupational therapy functional assessment with serial Pediatric Evaluation of Disability Inventory. RESULTS: While on therapy, the average annual increase in areal BMD was 48% and the average annual increase in BMD z score was 1.0. This increase in z score is statistically significant. There was no clear correlation between changes in BMD and fracture rate. All patients experienced functional improvement in mobility. CONCLUSIONS: Our results support the findings of Glorieux et al that cyclic administration of intravenous pamidronate in children with OI has beneficial effects with respect to BMD z scores and physical disability. Long-term follow-up will be required to determine whether bisphosphonate therapy will decrease fracture rates and increase mobility in children with moderate to severe OI.