Clinical features and GH response in 25 children with duplications in the <i>SHOX</i> region

OBJECTIVE: SHOX plays an important role in growth plate development and function. The clinical implications of duplications of the SHOX region remain uncertain. We evaluated phenotypic characteristics, genotype-phenotype correlations and the response to treatment with recombinant human growth hormone (rhGH) in children with duplications of the SHOX region. METHODS: Twenty-five children (15 boys, 10 girls) with a likely pathogenic duplication and >1 year of rhGH treatment were identified in the Dutch National Registry of GH treatment in children. RESULTS: We identified 23 different duplications of the SHOX region in 25 children. Median (IQR) height was -2.5 SDS (-3.0 to -2.1). The majority (76%) had features of SHOX haploinsufficiency, most frequently an increased sitting-height-to-height (SH/H) ratio. No height differences were found between duplication types. In 19 prepubertal children, median age at start of rhGH was 6.9 years (5.8 to 9.6), and median height gain after 1 year was 0.8 SDS (0.7 to 1.1). Adult height (AH) was reached in 7 children, with a median of -1.1 SDS (-2.1 to -0.3). For pubertal children, median age at start of rhGH was 12.0 years (11.0 to 13.6), and median height gain after 1 year was 0.4 SDS (0.1 to 0.8). AH was reached in 3 children, with a median of -2.9 SDS (-3.6 to -2.7). CONCLUSION: The majority of children had features associated with SHOX haploinsufficiency, with an increased SH/H ratio most frequently described. Furthermore, rhGH treatment leads to a significant growth response in prepubertal children with a duplication of the SHOX region.