ERN BOND: The key European network leveraging diagnosis, research, and treatment for rare bone conditions.

There is no universally accepted definition for rare diseases: in Europe a disease is considered to be rare when affecting fewer than 1 in 2000 people. European Reference Networks (ERNs) have been the concrete response to address the unmet needs of rare disease patients and many pan-European issues in the field, reducing inequities, and significantly increasing accessibility to high-quality healthcare across Europe. ERNs are virtual networks, involving centres and patient representatives with the general scope to facilitate discussion on complex cases requiring highly specialised competences and trained expertise. ERN BOND - the European Reference Network on rare BONe Diseases - is one of these 24 approved networks with the specific ongoing mission to implement measures facilitating multidisciplinary, holistic, continuous, patient-centred, and participative care provision to patients, and supporting them in the full realisation of their fundamental human rights. ERN BOND includes in 2023 a total of 53 centres of expertise from 20 European countries. Its governing structure installed in March 2017 includes decision-making, operative and consultative committees, which comprise experts in the field and patient representatives ensuring patient's voice and perspectives are taken into account. Over the years, ERN BOND has worked hard to achieve its mission and valuably contribute to the advancement of diagnosis, management, treatment, and research in rare diseases. The network activities are mainly related to (i) the provision of care which collectively involves averagely 2800 patients diagnosed per year, (ii) the development of education for and training of the healthcare personnel consisting until now in the realisation of 7 thematic workshops and 19 webinars, (iii) the dissemination and exchange and spread of knowledge via network's website (https://ernbond.eu/), social media channels, and newsletters, (iv) the management of related data through a disease registry currently mapping over 2300 cases and recording over 600 reported cases, and (v) the enhancement of research which now include two clinical trials endorsed by the network. ERN BOND represents therefore an unprecedented move to improve the healthcare management of patients suffering from rare bone diseases through European collaborations. This network, through the support from the European Health Programme, will continue to pursue its efforts to achieve its goals, always maintaining the patients and their families at the centre of healthcare services.

Treatment of congenital adrenal hyperplasia in children aged 0-3 years: a retrospective multicenter analysis of salt supplementation, glucocorticoid and mineralocorticoid medication, growth and blood pressure.

Objectives: International guidelines recommend additional salt supplementation during infancy in classic congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. The influence of corticoid medication and growth has not been assessed. Aim: To investigate the current use of salt supplementation, fludrocortisone (FC) and hydrocortisone (HC) dosage as well as weight, height, BMI and blood pressure (BP) in CAH children aged 0-3 years. Methods: Retrospective multicentre analysis using data from the I-CAH registry. Salt-treated (ST) and non-salt-treated (NST) children were compared regarding FC and HC dosage, weight, height and BP at 0, 3, 6, 9, 12, 18, 24, 30, and 36 months. Results: We analysed 2483 visits of 331 patients born after year 2000 in 13 countries (male, n = 145) with 203 ST patients (61%). NST children had significantly higher FC dosages at 1.5-4.5 months and higher HC dosages until 1.5 months of age. No differences in weight, length and BP between subgroups were observed. Children of the whole cohort showed increased BMI-SDS during the study period and about half of the reported BP readings were >P95. Conclusion: In children treated with additional salt supplementation, FC and HC dosages are lower during the first months of life but without differences in weight, length and BP until 3 years of age compared to NST children. All children showed an increase in BMI-SDS and a high rate of BP readings >P95 until 3 years, indicating the start of weight gain and negative effects on blood pressure already in very early life.

Spontaneous Growth and Effect of Early Therapy with Calcitriol and Phosphate in X-linked Hypophosphatemic Rickets.

Whereas nutritional vitamin D deficient rickets affects many people world-wide, X-linked hypophosphatemic rickets (XLH, MIM 307800) has a prevalence of only 1:25.000. Like other rare diseases burden of disease in XLH and the effect of the current standard of care are inadequately described. Only few height data of untreated patients with XLH have been published. Here we report on height before start of therapy of 127 patients with XLH from 49 centres. One investigator collected all data from patient files documented at regular visits by treating physicians. Height standard deviation score (HSDS) was calculated and the geometrical mean was analysed. At birth all patients had a documented height within the healthy reference population. In this cross-sectional analysis of documented height at time of diagnosis decelerates until a mean age of 4.3 years to a nadir, i.e. lowest HSDS of -3.2 HSDS. Afterwards a spontaneous catch-up growth of +1.3 HSDS occurs until start of puberty. To assess the impact of calcitriol and phosphate supplementation on growth we analysed from a cohort of 18 patients treated at the Dept. of Paediatrics at O.-v.-Guericke-University Magdeburg. In this subgroup, size at birth and all time lowest HSDS (r=0.56 p=0.002) are correlated as well as all time low HSDS and last height during puberty (r=0.62 p=0.001). 10 of 18 patients were treated before age 18 months. Within this group the mean HSDS decelerates to -2.2 SDS at age 4.4 y. and increased to -1.4 SDS at age 9.9 years. Adult height, i.e. mean age 17.6 years was -2.4 HSDS. In conclusion, untreated children with XLR are characterized by normal length at birth, diminished growth rate compared to reference children until 4.3 years and spontaneous catch-up growth of 1.3 HSDS until start of puberty. Improved growth rate in XLR children occured by combined phosphate and calcitriol treatment before 18 months.