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OA Förderung 2022 Background: Despite an intensive multimodal treatment approach, approximately 50% of high-risk (HR) neuroblastoma (NB) patients experience progression. Despite the advances in targeted therapy, high-dose chemotherapy, and other systemic treatment options, radiation therapy (RT) to sites of relapsed disease can be an option to reduce tumor burden and improve chance for disease control. Methods: Patients who received salvage irradiation with proton beam therapy (PBT) for local or metastatic relapse of HR NB within the prospective registry trials KiProReg and ProReg were eligible for this retrospective analysis. Data on patient characteristics, multimodality therapy, adverse events, and oncologic endpoints were evaluated. Adverse events were assessed before, during, and after PBT according to common terminology criteria for adverse events (CTCAE) V4.0. Results: Between September 2013 and September 2020, twenty (11 male; 9 female) consecutive patients experiencing local (N = 9) or distant recurrence (N = 25) were identified for this analysis. Distant recurrences included osteomedullary (N = 11) or CNS lesions (N = 14). Salvage therapy consisted of re-induction chemo- or chemo-immuno-therapy (N = 19), surgery (N = 6), high-dose chemotherapy and stem cell transplantation (N = 13), radiation (N = 20), and concurrent systemic therapy. Systemic therapy concurrent to RT was given to six patients and included temozolomide (N = 4), carboplatine (N = 1), or anaplastic lymphoma kinase tyrosine kinase inhibitors (ALK-TKI) (N = 1). A median dose of 36 Gy was applied to the 34 recurrent sites. Local RT was applied to 15 patients, while five patients, received craniospinal irradiation for CNS relapse. After a median follow-up (FU) of 20 months (4–66), the estimated rate for local control, distant metastatic free survival, and overall survival at 3 years was 68.0%, 37.9%, and 61.6%, respectively. During RT, ten patients (50%) presented with a higher-grade acute hematologic adverse event. Late higher-grade sequelae included transient myelitis with transverse section (N = 2) and secondary malignancy outside of the RT field (N = 1). Conclusion: Our study demonstrates the efficacy and safety of RT/PBT for recurrent HR NB in a multimodality second-line approach. To better define the role of RT for these patients, prospective studies would be desirable.

Good training is the basis for high job satisfaction and high-quality patient care in radiology. The aim of this survey was to record the current state of working conditions for residents in radiology training in Germany and to focus on the aspects of training and psychosocial workload. The description of the actual state should help to identify possible problem areas and to develop improvement approaches. At the beginning of 2018, we sent an electronic questionnaire to the German Roentgen Society (DRG), the German Association of Chairmen in Academic Radiology (KLR), the Chief Physician Forum of the DRG (CAFRAD) and the Forum of Registered Radiologists (FUNRAD) with the request to forward it to radiology residents. With 63 questions, the questionnaire covered seven essential areas of medical working and training conditions. In order to ensure interdisciplinary comparability, most questions were identical to previous surveys among residents of other disciplines. 643 residents started the survey. 501 (78 %) questionnaires were fully processed and included in the final analysis. 65 % of respondents were satisfied with their current job situation. At the same time, shortcomings, especially with regard to the reconciliation of family and work as well as scientific and clinical work, became clear. Only 36 % of participants with children were satisfied with the compatibility of family and work at their workplace. Only 31 % of the researchers were satisfied with their research conditions. In addition, residents experienced a high psychosocial workload. Job satisfaction is high among radiology residents in direct comparison to other disciplines. However, based on this survey, adjustments to working conditions and training in radiology seem necessary to maintain the health of the physicians concerned, to encourage motivation for scientific work and to enhance development opportunities, especially for women, through a better compatibility of work and family life. The present survey identifies strategies and leadership tools that can help to achieve this. Residents in radiology training ... · have a relatively high job satisfaction.. · experience a high psychosocial workload.. · evaluate the compatibility of family and work as in need of improvement.. · are interested in research, but evaluate research conditions as insufficient.· Oechtering TH, Panagiotopoulos N, Völker M et al. Work and Training Conditions of German Residents in Radiology - Results from a Nationwide Survey Conducted by the Young Radiology Forum in the German Roentgen Society. Fortschr Röntgenstr 2020; 192: 458 - 469.ZIEL: Eine qualitativ hochwertige Weiterbildung ist Grundlage für eine hohe Arbeitszufriedenheit und eine exzellente Patientenversorgung in der Radiologie. Ziel dieser Umfrage war es, den aktuellen Stand der Arbeitsbedingungen von Ärzten in der Weiterbildung Radiologie in Deutschland zu erfassen und einen Fokus auf die Teilaspekte Weiterbildung sowie psychosoziale Arbeitsbelastung zu legen. Die Beschreibung des Ist-Zustandes soll helfen, mögliche Problemfelder zu identifizieren und Verbesserungsansätze zu entwickeln. Anfang 2018 wurde ein elektronischer Fragebogen über die Deutsche Röntgengesellschaft (DRG) e. V., die Konferenz der Lehrstuhlinhaber für Radiologie (KLR), das Chefarztforum der DRG (CAFRAD) und das Forum Niedergelassener Radiologen (FUNRAD) an radiologische Weiterbildungsassistenten verschickt. Der Fragebogen deckte mit 63 Fragen 7 wesentliche Themenfelder ärztlicher Arbeits- und Weiterbildungsbedingungen ab. Um eine fächerübergreifende Vergleichbarkeit zu sichern, wurden Fragen von bisherigen Erhebungen unter Ärzten in Weiterbildung anderer Fachrichtungen übernommen. 643 Ärzte haben die Umfrage begonnen. 501 (78 %) Fragebögen wurden vollständig bearbeitet und in die endgültige Analyse einbezogen. 65 % der Befragten waren mit ihrer derzeitigen beruflichen Situation zufrieden. Gleichzeitig wurden Defizite besonders in Bezug auf die Vereinbarkeit von Familie und Beruf sowie die Möglichkeit zu wissenschaftlichem Arbeiten deutlich. Nur 36 % der Teilnehmer mit Kindern waren zufrieden mit der Vereinbarkeit von Familie und Beruf an ihrem Arbeitsplatz. Nur 31 % der wissenschaftlich Tätigen waren zufrieden mit ihren Forschungsbedingungen. Zudem war die psychosoziale Arbeitsbelastung unter den befragten Ärzten stark ausgeprägt. Die Arbeitszufriedenheit ist unter radiologischen Assistenzärzten im Vergleich zu anderen Fachrichtungen hoch. Dennoch scheinen auf Basis dieser Erhebung Anpassungen der Arbeits- und Weiterbildungsbedingungen in der Radiologie erforderlich, um die Gesundheit der betroffenen Ärzte zu erhalten, die Motivation für wissenschaftliches Arbeiten zu fördern und die Entwicklungsmöglichkeiten insbesondere von Frauen durch eine bessere Vereinbarkeit von Familie und Beruf aufzuwerten. Die vorliegende Umfrage zeigt Strategien und Führungsinstrumente auf, mit denen dies erreicht werden kann. Ärzte in radiologischer Weiterbildung ... · sind zufrieden mit ihrer beruflichen Situation.. · stehen unter hoher psychosozialer Arbeitsbelastung.. · bewerten die Vereinbarkeit von Familie und Beruf als verbesserungsbedürftig.. · sind an Forschung interessiert, bewerten die Forschungsbedingungen aber als unzureichend..· Oechtering TH, Panagiotopoulos N, Völker M et al. Work and Training Conditions of German Residents in Radiology – Results from a Nationwide Survey Conducted by the Young Radiology Forum in the German Roentgen Society. Fortschr Röntgenstr 2020; 192: 458 – 470.

Introduction Recently recessive mutations in sphingosine-1-phosphate lyase (SGPL1) have been published as a cause of syndromic congenital nephrotic syndrome with adrenal insufficiency. We have identified a case with fetal hydrops and brain malformations due to a mutation in SGPL1. Case report We report a patient presenting with severe fetal hydrops, congenital nephrotic syndrome and adrenal calcifications. MRI imaging showed generalized cortical atrophy with simplified gyral pattern and hypoplastic temporal lobes as well as cerebellar hypoplasia and hyperintensity in the pons. The boy deceased at 6 weeks of age. Via whole exome sequencing, we identified a novel homozygous frameshift mutation c.1233delC (p.Phe411Leufs∗56) in SGPL1. Conclusion In our patient, we describe a novel mutation in sphingosine-1-phosphate lyase (SGPL1) leading to severe brain malformation. Neurodevelopmental phenotypes have been reported earlier, but not described in detail. To this end, we present a review on all published SGPL1-mutations and genotype-phenotype correlations focusing on neurodevelopmental outcomes. We hypothesized on the severe neurological phenotypes, which might be due to disruption of neuronal autophagy. Mutations in SGPL1 shall be considered in the differential diagnosis of fetal hydrops as well as congenital brain malformations and neuropathies.

Central venous cannulation is widely used in neonatal critical care. Pericardial tamponade caused by vessel wall perforation can occur if the catheter tip induces extravasation at the level of the pericardium. To investigate the level of the superior pericardial reflection in stillborn babies. We dissected 20 bodies (11 female, mean gestational age 33 6/7 weeks, range 25–43 weeks), with careful opening of the thoracic area. After injecting contrast medium into the pericardial sac, we introduced a catheter through the right internal jugular vein. We then took radiographs to analyse the relationship between visual osseous landmarks and the pericardium. Mean distance between the pericardial reflection at its upper end and the first thoracic vertebra was 1.3 cm (standard deviation [SD]: 0.3 cm) and did not extend over the 3rd intercostal space. The mean distance from the entry of the superior vena cava into the pericardial sac and the 1st thoracic vertebra was 2.3 cm (SD: 0.5). The upper end of the pericardial reflection in neonates at autopsy lies below the middle of the 3rd thoracic vertebra. The tip of an upper inserted catheter should not extend below the level of the 3rd intercostal space.

Conventional lateral spine and hand radiographs are the standard tools to evaluate vertebral morphometry and bone age in children. Beside bone mineral density analyses, dual-energy X-ray absorptiometry (DXA) measurements with lower radiation exposure provide high-resolution scans which are not approved for diagnostic purposes. Data about the comparability of conventional radiographs and DXA in children are missing yet. The purpose of the trial was to evaluate whether conventional hand and spine radiographs can be replaced by DXA scans to diminish radiation exposure. Thirty-eight children with osteogenesis imperfecta or secondary osteoporosis or short stature (male, n=20; age, 5.0-17.0 yr) were included and assessed once by additional DXA (GE iDXA) of the spine or the left hand. Intraclass correlation coefficients (ICCs) were used to express agreement between X-ray and iDXA assessment. Evaluation of the spine morphometry showed reasonable agreement between iDXA and radiography (ICC for fish-shape, 0.75; for wedge-shape, 0.65; and for compression fractures, 0.70). Bone age determination showed excellent agreement between iDXA and radiography (ICC, 0.97). IDXA-scans of the spine in a pediatric population should be used not only to assess bone mineral density but also to evaluate anatomic structures and vertebral morphometry. Therefore, iDXA can replace some radiographs in children with skeletal diseases.

Aim Intraosseous (IO)-access plays an alternative route during resuscitation. Our study was performed to investigate the successful rate of IO-access in preterm and term stillborns using different devices and techniques. Methods The cadavers used were legal donations. 16 stillborns, median: 29.2 weeks (IQR 27.2–38.4) were investigated. Two different needles (a: Butterfly needle, 21G, Venofix® Fa.Braun; b: Arrow®EZ-IO®15G, Teleflex, Dublin, Ireland) were used. Needles were inserted i: manually, using a Butterfly needle; ii: manually, using EZ-IO® needle or iii: using a battery-powered semi-automatic drill (Arrow®EZ-IO®). Spectral-CT's were performed. The diameter of the corticalis was determined from the CT-images. Successful hit rates with 95% confidence intervals (CI) and odds ratios between the three methods were estimated using a generalised linear mixed model (GLMM). Results Estimated success rate was 61.1% (95%CI:39.7%–78.9%) for the Butterfly needle, 43.0% (95%CI:23.4%–65.0%) for hand-twisted EZ-IO® screwing and 39.7% (95%CI:24.1–57.7%) for the semi-automatic drill (Arrow®EZ-IO®), all referring to an average diameter of the corticalis of 1.2 mm. The odds of a correct position were 2.4 times higher (95%CI:0.8–7.6) when using the Butterfly needle than with the drill. In contrast, the odds of correct positioning when inserting the needle by hand were not significantly different from using the drill (odds ratio 1.1, 95%CI: 0.4–3.3). Neither of these effects nor the diameter of the corticalis with an odds ratio near one were significant in the model. Median diameter of the bone marrow cavity was 4.0 mm [IQR 3.3–4.7]. Conclusion Intraosseous access for premature and neonatal infants could be best achieved by using a manually twisted Butterfly needle.

Polycystic kidney disease (PKD) is among the leading causes of end-stage renal disease. Increasing evidence exists that molecular therapeutic strategies targeted to cyst formation and growth might be more efficacious in early disease stages, highlighting the growing need for sensitive biomarkers. Here we apply quantitative magnetic resonance imaging techniques of T2 mapping and diffusion-weighted imaging in the jck mouse model for PKD using a clinical 3.0 T scanner. We tested whether kidney T2 values and the apparent diffusion coefficient (ADC) are superior to anatomical imaging parameters in the detection of early cystogenesis, as shown on macro- and histopathology. We also tested whether kidney T2 values and ADC have the potential to monitor early treatment effects of therapy with the V2 receptor antagonist Mozavaptane. Kidney T2 values and to a lesser degree ADC were found to be highly sensitive markers of early cystogenesis and superior to anatomical-based imaging parameters. Furthermore, kidney T2 values exhibited a nearly perfect correlation to the histological cystic index, allowing a clear separation of the two mouse genotypes. Additionally, kidney T2 values and ADC were able to monitor early treatment effects in the jck mouse model in a proof-of-principle experiment. Thus, given the superiority of kidney T2 values and ADC over anatomical-based imaging in mice, further studies are needed to evaluate the translational impact of these techniques in patients with PKD.

We describe a consanguineous Iraqi family with Leber congenital amaurosis (LCA), Joubert syndrome (JBTS), and polycystic kidney disease (PKD). Targeted next-generation sequencing for excluding mutations in known LCA and JBTS genes, homozygosity mapping, and whole-exome sequencing identified a homozygous missense variant, c.317G>C (p.Arg106Pro), in POC1B, a gene essential for ciliogenesis, basal body, and centrosome integrity. In silico modeling suggested a requirement of p.Arg106 for the formation of the third WD40 repeat and a protein interaction interface. In human and mouse retina, POC1B localized to the basal body and centriole adjacent to the connecting cilium of photoreceptors and in synapses of the outer plexiform layer. Knockdown of Poc1b in zebrafish caused cystic kidneys and retinal degeneration with shortened and reduced photoreceptor connecting cilia, compatible with the human syndromic ciliopathy. A recent study describes homozygosity for p.Arg106ProPOC1B in a family with nonsyndromic cone-rod dystrophy. The phenotype associated with homozygous p.Arg106ProPOC1B may thus be highly variable, analogous to homozygous p.Leu710Ser in WDR19 causing either isolated retinitis pigmentosa or Jeune syndrome. Our study indicates that POC1B is required for retinal integrity, and we propose POC1B mutations as a probable cause for JBTS with severe PKD.

Background. The infantile form of primary hyperoxaluria type I (PHI) is the most devastating PH subtype leading to early end-stage renal failure and severe systemic oxalosis. Combined or sequential liver–kidney transplantation (LKTx) is the only curative option but it involves substantial risks, especially in critically ill infants. The procedure also requires resources that are simply not available to many children suffering from PHI worldwide. Less invasive and less complex therapeutic interventions allowing a better timing are clearly needed. Liver cell transplantation (LCT) may expand the narrow spectrum of auxiliary measures to buy time until LKTx for infants can be performed more safely. Methods. We performed LCT (male neonate donor) in a 15-month-old female in reduced general condition suffering from systemic oxalosis. Renal replacement therapy, initiated at the age of 3 months, was complicated by continuous haemodialysis access problems. Living donor liver transplantation was not available for this patient. Plasma oxalate (Pox) was used as the primary outcome measure. Results. Pox decreased from 104.3 6 8.4 prior to 70.0 6 15.0lmol/L from Day 14 to Day 56 after LCT. A significant persistent Pox reduction (P < 0.001) comparing mean levels prior to (103.8 lmol/L) and after Day 14 of LCT until LKTx (77.3 lmol/L) was seen, although a secondary increase and wider range of Pox was also observed. In parallel, the patient’s clinical situation markedly improved and the girl received a cadaveric LKTx 12 months after LCT. However, biopsy specimens taken from the explanted liver did not show male donor cells by amelogenin polymerase chain reaction. Conclusions. With due caution, our pilot data indicate that LCT in infantile oxalosis warrants further investigation. Improvement of protocol and methodology is clearly needed in order to develop a procedure that could assist in the cure of PHI.

Joubert syndrome (JBTS) is characterized by a specific brain malformation with various additional pathologies. It results from mutations in any one of at least 10 different genes, including NPHP1, which encodes nephrocystin-1. JBTS has been linked to dysfunction of primary cilia, since the gene products known to be associated with the disorder localize to this evolutionarily ancient organelle. Here we report the identification of a disease locus, JBTS12, with mutations in the KIF7 gene, an ortholog of the Drosophila kinesin Costal2, in a consanguineous JBTS family and subsequently in other JBTS patients. Interestingly, KIF7 is a known regulator of Hedgehog signaling and a putative ciliary motor protein. We found that KIF7 co-precipitated with nephrocystin-1. Further, knockdown of KIF7 expression in cell lines caused defects in cilia formation and induced abnormal centrosomal duplication and fragmentation of the Golgi network. These cellular phenotypes likely resulted from abnormal tubulin acetylation and microtubular dynamics. Thus, we suggest that modified microtubule stability and growth direction caused by loss of KIF7 function may be an underlying disease mechanism contributing to JBTS.

Introduction Percutaneous renal biopsy (PRB) is a decisive diagnostic procedure for children and adolescents with renal diseases. Aim of this study was to evaluate retrospectively the complication rates of percutaneous kidney biopsies and their therapeutic consequences to assess the role of ultrasound-guidance including Doppler ultrasound examinations in preparation, execution and follow-up care and to present a recommended protocol. Patients and Methods Institutional review board approved this retrospective study; informed consent was waived. Between 1997 and 2011 a total of 438 ultrasound-guided biopsies were performed in 295 patients, 169 of the biopsies were performed on kidney transplants. Average age of patients was 10.2+/−5.2 years (range of 15 days until age of 23). Before and post biopsy ultrasound examination including Doppler examination was carried out. Biopsy itself was ultrasound monitored. Complications were analysed with regard to age of patient, kidney transplants, year of occurrence, number of punctures, performing physician and time interval of occurrence to develop an optimized protocol for ultrasound-guidance. Results In 99% of cases successful PRB were performed, i.e. enough kidney parenchyma for histological analysis was obtained. No lethal or major complication that required surgical intervention occurred. Eighteen relevant complications were observed (complication rate: 4.1%). Except in one case in which additional MRI diagnostic was necessary, ultrasound examination after 4 hours post biopsy or even earlier when symptoms occurred, was able to detect complications and determine indications for intervention. Conclusion Ultrasound-guided PRB is an established and effective method in children and adolescents, but shows a certain rate of complications and therefore should not be indicated without diligence. Ultrasound including Doppler ultrasound is a valuable tool in preparation, guidance of biopsy, detection of complications and in follow-up care. Ultrasound examinations (including Doppler) pre-, during and 4 hours post kidney biopsy and, depending from case, a few days until weeks after biopsy is recommended.

Background Osteogenesis imperfecta (OI) is a hereditary disease causing reduced bone mass, increased fracture rate, long bone deformities and vertebral compressions. Additional non skeletal findings are caused by impaired collagen function and include hyperlaxity of joints and blue sclera. Most OI cases are caused by dominant mutations in COL1A1/2 affecting bone formation. During the last years, recessive forms of OI have been identified, mostly affecting posttranslational modification of collagen. In 2011, mutations in SERPINF1 were identified as the molecular cause of OI type VI, and thereby a novel pathophysiology of the disease was elucidated. The subgroup of patients with OI type VI are affected by an increased bone resorption, leading to the same symptoms as observed in patients with an impaired bone formation. Severely affected children are currently treated with intravenous bisphosphonates regardless of the underlying mutation and pathophysiology. Patients with OI type VI are known to have a poor response to such a bisphosphonate treatment. Method Deciphering the genetic cause of OI type VI in our 4 patients (three children and one adolescent) led to an immediate translational approach in the form of a treatment with the monoclonal RANKL antibody Denosumab (1 mg/kg body weight every 12 weeks). Results Short-term biochemical response to this treatment was reported previously. We now present the results after 2 years of treatment and demonstrate a long term benefit as well as an increase of bone mineral density, a normalization of vertebral shape, an increase of mobility, and a reduced fracture rate. Conclusion This report presents the first two-year data of denosumab treatment in patients with Osteogenesis imperfecta type VI and in Osteogenesis imperfecta in general as an effective and apparently safe treatment option.

Purpose Resection is generally considered the gold standard for treatment of low-grade (WHO grades I and II) gliomas (LGGs) in childhood. However, approximately 30% to 50% of these tumors are inoperable because of their localization in highly eloquent brain areas. A few reports have suggested stereotactic brachytherapy (SBT) with implantation of iodine-125 (125I) seeds as a safe and effective local treatment alternative. This single-center study provides a summary of the long-term outcome after SBT in one of the largest reported patient series. Patients and Methods All pediatric patients treated with SBT (125I seeds; cumulative therapeutic dose 50-65 Gy within 9 months) by our group for LGG with follow-up of more than 6 months were included. Clinical and radiologic outcome, time to progression, and overall survival were evaluated. Prognostic factors (age, sex, Karnofsky performance score, tumor volume, and histology) for survival and disease progression were investigated. Results In all, 147 of 160 pediatric patients treated with SBT (from 1982 through 2009) were analyzed in detail. Procedure-related mortality was zero, and the 30-day morbidity was transient and low (5.4%). Survival rates at 5 and 10 years were 93%, and 82%, respectively, with no significant difference between WHO grades I and II tumors (median follow-up, 67.1 ± 57.7 months). Twenty-one (14.8%) of 147 patients presented with tumor relapse. The remaining 126 patients revealed complete response in 24.6%, partial response in 31.0%, and stable disease in 29.6%. Neurologic status improved (57.8%) or remained stable (23.0%). None of the evaluated factors had significant impact on the study's end points except tumor volume more than 15 mL, which caused significantly higher rates of tumor recurrence (P < .05). Conclusion We demonstrate that SBT represents a safe, minimally invasive, and highly effective local treatment option for pediatric patients with inoperable LGG WHO grades I and II.

Background/Aims: Osteogenesis imperfecta (OI) is a hereditary disease causing increased bone fragility. Pamidronate (PAM), which has to be administered as a 3-day course according to the original protocol by Glorieux, is the most frequently used therapy. Other bisphosphonates like neridronate (NER), which can be infused during an outpatient visit, have also proven to be effective. This is the first analysis comparing the effect of PAM and NER using vertebral morphometry. Methods: 28 patients with OI type III and IV were retrospectively analyzed by matched pairs. Results: No differences were detected between patients treated with PAM or NER at the start of therapy: mean age 4.4 years (p = 0.730), mean height 86.8 cm/85.3 cm (p = 0.854), lumbar vertebral area 208.9 mm2/206.0 mm2 (p = 0.555), and in all vertebral indices. After 1 year of treatment (mean 1.16 years; p = 0.854) both groups showed a significant increase in the vertebral area and improved vertebral indices. Again there were no differences between the groups in the vertebral area (p = 0.590). Conclusion: In this study there was no difference between patients treated with PAM or NER regarding vertebral morphometry during the first year of therapy. Because of the possibility of an outpatient setting, NER is convenient for these children.

Hyperphosphatemic Familial Tumoral Calcinosis (HFTC; MIM211900) is a rare autosomal recessive disorder characterized by the progressive deposition of calcified masses in cutaneous and subcutaneous tissues, associated with elevated circulating levels of phosphate. The disease was initially found to result from mutations in GALNT3 encoding a glycosyltransferase. However, more recently, the S71G missense mutation in FGF23, encoding a potent phosphaturic protein, was identified in two families. In the present report, we describe a second mutation in FGF23 underlying a severe case displaying calcifications of cutaneous and numerous extracutaneous tissues. The mutation (M96T) was found to affect a highly conserved methionine residue at position 96 of the protein. These observations illustrate the extent of genetic and phenotypic heterogeneity in HFTC.

et al., We report that hypofunctional alleles of WNT1 cause autosomal-recessive osteogenesis imperfecta, a congenital disorder characterized by reduced bone mass and recurrent fractures. In consanguineous families, we identified five homozygous mutations in WNT1: one frameshift mutation, two missense mutations, one splice-site mutation, and one nonsense mutation. In addition, in a family affected by dominantly inherited early-onset osteoporosis, a heterozygous WNT1 missense mutation was identified in affected individuals. Initial functional analysis revealed that altered WNT1 proteins fail to activate canonical LRP5-mediated WNT-regulated β-catenin signaling. Furthermore, osteoblasts cultured in vitro showed enhanced Wnt1 expression with advancing differentiation, indicating a role of WNT1 in osteoblast function and bone development. Our finding that homozygous and heterozygous variants in WNT1 predispose to low-bone-mass phenotypes might advance the development of more effective therapeutic strategies for congenital forms of bone fragility, as well as for common forms of age-related osteoporosis., This work was supported by German Federal Ministry of Education and Research grants 01GM1211A (E-RARE network CRANIRARE-2), 01GM1109C (national rare disease network Forschungsverbund Ausgewählter Craniofacialer Entwicklungsstörungen) to B.W., and 01EC1006A (Molecular Pathogenesis of Osteoporosis) to U.K. and S.M., by TÜBITAK grant 112S398 (E-RARE network CRANIRARE-2) to H.K., and by National Institute of Child Health and Human Development (National Institutes of Health) Intramural Research Program funding to S.L. and J.C.M. M.S. holds a Doc female forte scholarship from Austria and is a member of the Berlin-Brandenburg School for Regenerative Therapies.