Variable outcome of growth hormone administration in respiratory chain deficiency

Genetic defects of oxidative phosphorylation (OXPHOS) are known to account for a variety of neuromuscular and non-neuromuscular symptoms in childhood, including growth hormone (GH) deficiency. However GH administration for GH deficiency is controversial in OXPHOS deficiencies as GH is a mitosis-stimulator which may increase energy demand for cell proliferation. Here, we report the observation of four unrelated children with OXPHOS deficiency or bearing a mitochondrial DNA rearrangement and growth retardation, who required GH therapy. The first patient had no GH deficiency while the other three had low GH response to test stimulations. The condition of the first two patients quickly deteriorated under GH administration, GH was then stopped and subsequent clinical improvement was noted. In the other two patients, no adverse event was noted but various additional organs were involved following GH administration. In all patients, no benefit was observed concerning growth response as growth speed remained unchanged. These observations question the use of GH as a treatment of growth retardation for patients with OXPHOS deficiency.