Bone disease in patients with phenylketonuria (PKU) is incompletely characterized. We therefore analyzed, in a cross-sectional study radius macroscopic bone architecture and forearm muscle size by peripheral quantitative computed tomography (pQCT) and muscle strength by hand dynamometry in a large cohort (n = 56) of adolescent and adult patients with PKU aged 26.0 ± 8.9 (range, 11.8-41.5) years. Data were compared with a reference population (n = 700) from the DONALD study using identical methodology. We observed a significant reduction of cortical thickness (z-score -1.01 ± 0.79), Strength-Strain Index (SSI) (z-score -0.81 ± 1.03), and total bone mineral density (BMD) of the distal radius (z-score -1.05 ± 1.00). Mean muscle cross-sectional area (z-score -0.98 ± 1.19) and muscle grip force (z-score -0.64 ± 1.26) were also significantly reduced, indicating an impaired muscular system as part of the clinical phenotype of PKU. SSI positively correlated (r = 0.53, P< 0.001) with the corresponding muscle cross-sectional area in the reference population; however, the regression line slope in PKU patients was less steep (P < 0.001), indicating that bone strength is not adequately adapted to muscle force. In conclusion, the radial bone in PKU patients is characterized by reduced bone strength in relation to muscular force, decreased cortical thickness, and impaired total BMD at the metaphyseal site. These alterations indicate a mixed bone defect in PKU, both of which are due to primary alterations of bone metabolism and to secondary alterations in response to neuromuscular abnormalities.
In two independent ongoing next-generation sequencing projects for individuals with holoprosencephaly and individuals with disorders of sex development, and through international research collaboration, we identified twelve individuals with de novo loss-of-function (LoF) variants in protein phosphatase 1, regulatory subunit 12a (PPP1R12A), an important developmental gene involved in cell migration, adhesion, and morphogenesis. This gene has not been previously reported in association with human disease, and it has intolerance to LoF as illustrated by a very low observed-to-expected ratio of LoF variants in gnomAD. Of the twelve individuals, midline brain malformations were found in five, urogenital anomalies in nine, and a combination of both phenotypes in two. Other congenital anomalies identified included omphalocele, jejunal, and ileal atresia with aberrant mesenteric blood supply, and syndactyly. Six individuals had stop gain variants, five had a deletion or duplication resulting in a frameshift, and one had a canonical splice acceptor site loss. Murine and human in situ hybridization and immunostaining revealed PPP1R12A expression in the prosencephalic neural folds and protein localization in the lower urinary tract at critical periods for forebrain division and urogenital development. Based on these clinical and molecular findings, we propose the association of PPP1R12A pathogenic variants with a congenital malformations syndrome affecting the embryogenesis of the brain and genitourinary systems and including disorders of sex development.
Background: Paediatric prolactinomas are rare. The aim of this study was to investigate the clinical features and outcome of paediatric patients with prolactinomas. Methods: In this single-centre retrospective analysis, clinical, biochemical, and radiological features of all paediatric patients with pituitary adenomas diagnosed between 2000 and 2016 were evaluated. Results: Among 21 patients with pituitary adenomas, 12 patients with prolactinomas (median age 14.2 years, range 11–16.6 years, 8 females, 4 males) were identified (7 macro- and 5 microprolactinomas). The most common clinical symptoms were headaches (67%) and pubertal delay (67%). All patients with macroprolactinomas with prolactin concentrations >10,000 mU/L had at least 1 pituitary hormone deficiency. Cabergoline as first-line treatment (n = 11, median follow-up of 37 months, range 12–89 months) induced normoprolactinemia (n = 8), reduced the mean tumour volume by 80%, and ameliorated headaches (p = 0.016) and pubertal delay (p = 0.031), whereas intermittent moderate side effects occurred in 55%. Conclusion: Adolescents with headaches and pubertal delay should be investigated for prolactinomas. Treatment with cabergoline is well tolerated and effective in reducing clinical symptoms and prolactin concentrations was well as inducing tumour shrinkage. Further clinical prospective studies are needed to standardize paediatric treatment modalities.
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