Case Report: Osteosclerotic metaphyseal dysplasia with optic nerve involvement and progressive osteonecrosis of the jaw due to a novel LRRK1 mutation.

Background: Osteosclerotic metaphyseal dysplasia (OSMD, OMIM 615198) is an extremely rare autosomal recessive osteopetrosis disorder resulting in a distinctive pattern of osteosclerosis of the metaphyseal margins of long tubular bones. To date, only thirteen cases have been reported (eight molecularly confirmed). Five homozygous sequence variants in the leucine-rich repeat kinase 1 (LRRK1) gene have been identified to cause OSMD. We present two male siblings with OSMD with a novel LRRK1 variant. Cases: The index case, now aged 6 years, was referred aged 9 months when diffuse sclerosis of the ribs and vertebral bodies, suggestive of osteopetrosis, was incidentally identified on a chest radiograph for suspected lower respiratory tract infection. Parents were consanguineous and of Pakistani origin. Further evaluation revealed developmental delay, nystagmus with bilateral optic nerve hypoplasia and severe visual impairment. Skeletal survey confirmed typical changes of OSMD, with widespread diffuse sclerosis and Erlenmeyer flask deformity of long bones. His older sibling, now aged 12 years, was 7 years at the time of referral and had similar clinical course and skeletal findings. Additionally, he had a chronic progressive osteonecrosis of the left mandible that required debridement, debulking and long-term antibiotics. Skeletal survey revealed findings similar to his sibling. Neither sibling had significant skeletal fractures or seizures. Unlike most previous reports suggesting sparing of the skull and lack of visual impairment, our patients had evidence of osteosclerosis of the cranium. Genetic screening for the common autosomal recessive and dominant pathogenic variants of osteopetrosis was negative. Whole Exome Sequencing (WES) followed by Sanger sequencing, identified a novel homozygous LRRK1 c.2506C>T p. (Gln836Ter) nonsense variant predicted to result in premature truncation of LRRK1 transcript. Conclusion: Our cases confirm the autosomal recessive inheritance and expand the spectrum of genotype and phenotype of OSMD reported in the literature. Increasing reports of LRRK1 variants in this phenotype raise the question of whether LRRK1 should be included in targeted osteopetrosis panels. Bone histology in previous cases has shown this to be an osteoclast rich form of osteopetrosis raising the possibility that haematopoietic stem cell transplantation may be an appropriate treatment modality.

Biallelic KIF24 Variants Are Responsible for a Spectrum of Skeletal Disorders Ranging From Lethal Skeletal Ciliopathy to Severe Acromesomelic Dysplasia.

Skeletal dysplasias comprise a large spectrum of mostly monogenic disorders affecting bone growth, patterning, and homeostasis, and ranging in severity from lethal to mild phenotypes. This study aimed to underpin the genetic cause of skeletal dysplasia in three unrelated families with variable skeletal manifestations. The six affected individuals from three families had severe short stature with extreme shortening of forelimbs, short long-bones, and metatarsals, and brachydactyly (family 1); mild short stature, platyspondyly, and metaphyseal irregularities (family 2); or a prenatally lethal skeletal dysplasia with kidney features suggestive of a ciliopathy (family 3). Genetic studies by whole genome, whole exome, and ciliome panel sequencing identified in all affected individuals biallelic missense variants in KIF24, which encodes a kinesin family member controlling ciliogenesis. In families 1 and 3, with the more severe phenotype, the affected subjects harbored homozygous variants (c.1457A>G; p.(Ile486Val) and c.1565A>G; p.(Asn522Ser), respectively) in the motor domain which plays a crucial role in KIF24 function. In family 2, compound heterozygous variants (c.1697C>T; p.(Ser566Phe)/c.1811C>T; p.(Thr604Met)) were found C-terminal to the motor domain, in agreement with a genotype-phenotype correlation. In vitro experiments performed on amnioblasts of one affected fetus from family 3 showed that primary cilia assembly was severely impaired, and that cytokinesis was also affected. In conclusion, our study describes novel forms of skeletal dysplasia associated with biallelic variants in KIF24. To our knowledge this is the first report implicating KIF24 variants as the cause of a skeletal dysplasia, thereby extending the genetic heterogeneity and the phenotypic spectrum of rare bone disorders and underscoring the wide range of monogenetic skeletal ciliopathies. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Genetic Characterization of Short Stature Patients With Overlapping Features of Growth Hormone Insensitivity Syndromes.

CONTEXT: Growth hormone insensitivity (GHI) in children is characterized by short stature, functional insulin-like growth factor (IGF)-I deficiency, and normal or elevated serum growth hormone (GH) concentrations. The clinical and genetic etiology of GHI is expanding. OBJECTIVE: We undertook genetic characterization of short stature patients referred with suspected GHI and features which overlapped with known GH-IGF-I axis defects. METHODS: Between 2008 and 2020, our center received 149 GHI referrals for genetic testing. Genetic analysis utilized a combination of candidate gene sequencing, whole exome sequencing, array comparative genomic hybridization, and a targeted whole genome short stature gene panel. RESULTS: Genetic diagnoses were identified in 80/149 subjects (54%) with 45/80 (56%) having known GH-IGF-I axis defects (GHR n = 40, IGFALS n = 4, IGFIR n = 1). The remaining 35/80 (44%) had diagnoses of 3M syndrome (n = 10) (OBSL1 n = 7, CUL7 n = 2, and CCDC8 n = 1), Noonan syndrome (n = 4) (PTPN11 n = 2, SOS1 n = 1, and SOS2 n = 1), Silver-Russell syndrome (n = 2) (loss of methylation on chromosome 11p15 and uniparental disomy for chromosome 7), Class 3-5 copy number variations (n = 10), and disorders not previously associated with GHI (n = 9) (Barth syndrome, autoimmune lymphoproliferative syndrome, microcephalic osteodysplastic primordial dwarfism type II, achondroplasia, glycogen storage disease type IXb, lysinuric protein intolerance, multiminicore disease, macrocephaly, alopecia, cutis laxa, and scoliosis syndrome, and Bloom syndrome). CONCLUSION: We report the wide range of diagnoses in 149 patients referred with suspected GHI, which emphasizes the need to recognize GHI as a spectrum of clinical entities in undiagnosed short stature patients. Detailed clinical and genetic assessment may identify a diagnosis and inform clinical management.

Correction to: Best practice management guidelines for fibrous dysplasia/McCune-Albright syndrome: a consensus statement from the FD/MAS international consortium.

The original version of this article [1] unfortunately included an error to an author's name. Paul Arundel was inadvertently presented as Paul Arunde.

Best practice management guidelines for fibrous dysplasia/McCune-Albright syndrome: a consensus statement from the FD/MAS international consortium.

Fibrous Dysplasia / McCune Albright syndrome (FD/MAS) represents a wide spectrum of diseases due to somatic gain-of-function mutations of the GNAS gene. The mutation leads to overactivity in the target tissues and to a wide phenotype of clinical features that vary in severity and age of onset. The rarity of the disease and its variable presentation to multiple specialities often leads to misdiagnosis and inappropriate variability in investigations and treatments. To address this, our international consortium of clinicians, researchers, and patients' advocates has developed pragmatic clinical guidelines for best clinical practice for the definition, diagnosis, staging, treatment and monitoring for FD/MAS to empower patients and support clinical teams in both general and specialised healthcare settings. With the lack of strong evidence to inform care, the guidelines were developed based on review of published literature, long-standing extensive experience of authors, input from other healthcare professionals involved in the care of FD/MAS patients and feedback from patients and patient groups across the globe. This has led to the formulation of a set of statements to inform healthcare professionals, patients, their families, carers and patient groups of the best practice of care. It is anticipated the implementation of these recommendations will lead to improvement in the care of patients with FD/MAS internationally.

Cumulative radiation exposure from medical imaging and associated lifetime cancer risk in children with osteogenesis imperfecta.

OBJECTIVES: To estimate the cumulative effective dose of radiation (E) and additional lifetime attributable risk (LAR) of cancer from ionizing radiation in children with osteogenesis imperfecta (OI), who require frequent imaging for fractures and bone densitometry (DXA) surveillance. Also, to evaluate the pattern of long bone fractures. METHODS: We reviewed all imaging (x-rays, DXA and computed tomography [CT]) conducted in a cohort of children with OI with a minimum observation period of 5 years. For each image, E was estimated using age-dependent local data, and LAR of cancer was extrapolated. LAR and fracture data were compared among children with mild, moderate and severe OI. LAR was allocated to cancer risk categories, and the moderate risk group (1 in 1000 to 1 in 100) was evaluated further. RESULTS: Results from 106 children with OI (50% females, 5747 images) are presented, with a median (range) observation period of 11.7 (5.2-15.6) years. CT accounted for 0.8% of total imaging procedures but contributed to 66% of total E. The overall LAR of cancer was minimal, averaging an additional 8.8 cases per 100,000 exposed patients (0.8-403). LAR was significantly lower in children with mild OI compared to those with moderate (p = 0.006) and severe OI (p = 0.001). All patients with a moderate LAR of cancer (n = 8) had undergone CT scans and 88% had scoliosis or vertebral fractures. The cohort experienced 412 long bone fractures, with the most common site being the femur (26.5%). OI severity correlated positively with long bone fracture rates (p < 0.001). CONCLUSIONS: When compared to baseline LAR of cancer (50%) the additional cancer risk from ionizing radiation imaging in our paediatric OI cohort was small (0.0088%). To reduce additional cancer risk, we recommend replacing spinal x-rays with vertebral fracture assessments on DXA and exercising caution with CT imaging.

Phenotypic Spectrum in Osteogenesis Imperfecta Due to Mutations in TMEM38B: Unraveling a Complex Cellular Defect.

Context: Recessive mutations in TMEM38B cause type XIV osteogenesis imperfecta (OI) by dysregulating intracellular calcium flux. Objectives: Clinical and bone material phenotype description and osteoblast differentiation studies. Design and Setting: Natural history study in pediatric research centers. Patients: Eight patients with type XIV OI. Main Outcome Measures: Clinical examinations included bone mineral density, radiographs, echocardiography, and muscle biopsy. Bone biopsy samples (n = 3) were analyzed using histomorphometry, quantitative backscattered electron microscopy, and Raman microspectroscopy. Cellular differentiation studies were performed on proband and control osteoblasts and normal murine osteoclasts. Results: Type XIV OI clinical phenotype ranges from asymptomatic to severe. Previously unreported features include vertebral fractures, periosteal cloaking, coxa vara, and extraskeletal features (muscular hypotonia, cardiac abnormalities). Proband lumbar spine bone density z score was reduced [median -3.3 (range -4.77 to +0.1; n = 7)] and increased by +1.7 (1.17 to 3.0; n = 3) following bisphosphonate therapy. TMEM38B mutant bone has reduced trabecular bone volume, osteoblast, and particularly osteoclast numbers, with >80% reduction in bone resorption. Bone matrix mineralization is normal and nanoporosity low. We demonstrate a complex osteoblast differentiation defect with decreased expression of early markers and increased expression of late and mineralization-related markers. Predominance of trimeric intracellular cation channel type B over type A expression in murine osteoclasts supports an intrinsic osteoclast defect underlying low bone turnover. Conclusions: OI type XIV has a bone histology, matrix mineralization, and osteoblast differentiation pattern that is distinct from OI with collagen defects. Probands are responsive to bisphosphonates and some show muscular and cardiovascular features possibly related to intracellular calcium flux abnormalities.

Hypopituitarism in children with cerebral palsy.

Poor growth and delayed puberty in children with cerebral palsy is frequently felt to be related to malnutrition. Although growth hormone deficiency is commonly described in these children, multiple pituitary hormone deficiency (MPHD) has not been previously reported. We present a series of four children with cerebral palsy who were born before 29 weeks gestation who were referred to the regional endocrinology service, three for delayed puberty and one for short stature, in whom investigations identified MPHD. All patients had a height well below -2 standard deviation score (2nd centile) at presentation and three who had MRI scans had an ectopic posterior pituitary gland. We therefore recommend that the possibility of MPHD should be considered in all children with cerebral palsy and poor growth or delayed puberty. Early diagnosis and treatment is essential to maximise growth and prevent associated morbidity and mortality.

Loss of Functional Osteoprotegerin: More Than a Skeletal Problem.

Introduction: Juvenile Paget's disease (JPD), an ultra-rare, debilitating bone disease due to loss of functional osteoprotegerin (OPG), is caused by recessive mutations in TNFRFSF11B. A genotype-phenotype correlation spanning from mild to very severe forms is described. Aim: This study aimed to describe the complexity of the human phenotype of OPG deficiency in more detail and to investigate heterozygous mutation carriers for clinical signs of JPD. Patients: We investigated 3 children with JPD from families of Turkish, German, and Pakistani descent and 19 family members (14 heterozygous). Results: A new disease-causing 4 bp-duplication in exon 1 was detected in the German patient, and a microdeletion including TNFRFSF11B in the Pakistani patient. Skeletal abnormalities in all affected children included bowing deformities and fractures, contractures, short stature and skull involvement. Complex malformation of the inner ear and vestibular structures (2 patients) resulted in early deafness. Patients were found to be growth hormone deficient (2), displayed nephrocalcinosis (1), and gross motor (3) and mental (1) retardation. Heterozygous family members displayed low OPG levels (12), elevated bone turnover markers (7), and osteopenia (6). Short stature (1), visual impairment (2), and hearing impairment (1) were also present. Conclusion: Diminished OPG levels cause complex changes affecting multiple organ systems, including pituitary function, in children with JPD and may cause osteopenia in heterozygous family members. Diagnostic and therapeutic measures should aim to address the complex phenotype.

Global Consensus Recommendations on Prevention and Management of Nutritional Rickets.

BACKGROUND: Vitamin D and calcium deficiencies are common worldwide, causing nutritional rickets and osteomalacia, which have a major impact on health, growth, and development of infants, children, and adolescents; the consequences can be lethal or can last into adulthood. The goals of this evidence-based consensus document are to provide health care professionals with guidance for prevention, diagnosis, and management of nutritional rickets and to provide policy makers with a framework to work toward its eradication. EVIDENCE: A systematic literature search examining the definition, diagnosis, treatment, and prevention of nutritional rickets in children was conducted. Evidence-based recommendations were developed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system that describe the strength of the recommendation and the quality of supporting evidence. PROCESS: Thirty-three nominated experts in pediatric endocrinology, pediatrics, nutrition, epidemiology, public health, and health economics evaluated the evidence on specific questions within five working groups. The consensus group, representing 11 international scientific organizations, participated in a multiday conference in May 2014 to reach a global evidence-based consensus. RESULTS: This consensus document defines nutritional rickets and its diagnostic criteria and describes the clinical management of rickets and osteomalacia. Risk factors, particularly in mothers and infants, are ranked, and specific prevention recommendations including food fortification and supplementation are offered for both the clinical and public health contexts. CONCLUSION: Rickets, osteomalacia, and vitamin D and calcium deficiencies are preventable global public health problems in infants, children, and adolescents. Implementation of international rickets prevention programs, including supplementation and food fortification, is urgently required.

Global Consensus Recommendations on Prevention and Management of Nutritional Rickets.

BACKGROUND: Vitamin D and calcium deficiencies are common worldwide, causing nutritional rickets and osteomalacia, which have a major impact on health, growth, and development of infants, children, and adolescents; the consequences can be lethal or can last into adulthood. The goals of this evidence-based consensus document are to provide health care professionals with guidance for prevention, diagnosis, and management of nutritional rickets and to provide policy makers with a framework to work toward its eradication. EVIDENCE: A systematic literature search examining the definition, diagnosis, treatment, and prevention of nutritional rickets in children was conducted. Evidence-based recommendations were developed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system that describes the strength of the recommendation and the quality of supporting evidence. PROCESS: Thirty-three nominated experts in pediatric endocrinology, pediatrics, nutrition, epidemiology, public health, and health economics evaluated the evidence on specific questions within five working groups. The consensus group, representing 11 international scientific organizations, participated in a multiday conference in May 2014 to reach a global evidence-based consensus. RESULTS: This consensus document defines nutritional rickets and its diagnostic criteria and describes the clinical management of rickets and osteomalacia. Risk factors, particularly in mothers and infants, are ranked, and specific prevention recommendations including food fortification and supplementation are offered for both the clinical and public health contexts. CONCLUSION: Rickets, osteomalacia, and vitamin D and calcium deficiencies are preventable global public health problems in infants, children, and adolescents. Implementation of international rickets prevention programs, including supplementation and food fortification, is urgently required.

Sunshine and vitamin D.

Vitamin D is vital for bone health and its deficiency deemed as a disease of the past has re-emerged as an important health concern. Exposure of the skin to solar ultraviolet B radiation is the major source of vitamin D and only a small proportion is derived from dietary intake. We review the various factors that influence the cutaneous synthesis of vitamin D and the recommendations regarding safe sun exposure and dietary supplementation to achieve adequate vitamin D levels proposed for optimal bone health.

A Practical Approach to Vitamin D Deficiency and Rickets.

Rickets is a condition in which there is failure of the normal mineralisation (osteomalacia) of growing bone. Whilst osteomalacia may be present in adults, rickets cannot occur. It is generally caused by a lack of mineral supply, which can either occur as a result of the deficiency of calcium (calciopaenic rickets, now known as parathyroid hormone-dependent rickets) or of phosphate (phosphopaenic rickets, now called FGF23-dependent rickets). Renal disorders may also interfere with the process of mineralisation and cause rickets. Only parathyroid hormone-dependent rickets and distal renal tubular disorders will be discussed in this chapter. The most common cause of rickets is still vitamin D deficiency, which is also responsible for other problems. Disorders of vitamin D metabolism or responsiveness may also cause similar issues. Distal renal tubular acidosis may also be caused by a variety of metabolic errors similar to those of osteoclasts. One form of distal renal tubular acidosis also causes a type of osteopetrosis. This chapter describes these conditions in detail and sets out a logical approach for treatment.

Case Histories.

Conditions related to abnormalities of calcium and bone metabolism are large in number and are characterised by hypocalcaemia, hypercalcaemia, primary and secondary osteoporosis, rickets resulting from both vitamin D and phosphate metabolism disorders, and a series of miscellaneous conditions. Included in this chapter is a series of cases drawn from our clinics and from colleagues who have presented these clinical problems at the recent Advanced Courses in Paediatric Bone and Calcium Metabolism run by the British Paediatric and Adolescent Bone group. This series of cases is not fully comprehensive but is designed to cover the major aspects of bone- and calcium-related disorders.

Neomycin improves cationic lipid-mediated transfection of DNA in human cells.

Delivery of oligonucleotides has been a major impediment in the development of nucleic acid based drugs. In this report, we show that neomycin, an aminoglycoside antibiotic, when combined with a cationic lipid preparation such as DOTAP, enhances transfection efficiency of both reporter plasmids and oligonucleotides and results in a significant increase in transgene expression. The results described here open a new lead in ongoing efforts for oligonucleotide delivery.

Mutations that cause osteoglophonic dysplasia define novel roles for FGFR1 in bone elongation.

Activating mutations in the genes for fibroblast growth factor receptors 1-3 (FGFR1-3) are responsible for a diverse group of skeletal disorders. In general, mutations in FGFR1 and FGFR2 cause the majority of syndromes involving craniosynostosis, whereas the dwarfing syndromes are largely associated with FGFR3 mutations. Osteoglophonic dysplasia (OD) is a "crossover" disorder that has skeletal phenotypes associated with FGFR1, FGFR2, and FGFR3 mutations. Indeed, patients with OD present with craniosynostosis, prominent supraorbital ridge, and depressed nasal bridge, as well as the rhizomelic dwarfism and nonossifying bone lesions that are characteristic of the disorder. We demonstrate here that OD is caused by missense mutations in highly conserved residues comprising the ligand-binding and transmembrane domains of FGFR1, thus defining novel roles for this receptor as a negative regulator of long-bone growth.

Wolcott-Rallison Syndrome: clinical, genetic, and functional study of EIF2AK3 mutations and suggestion of genetic heterogeneity.

Wolcott-Rallison syndrome (WRS) is a rare autosomal-recessive disorder characterized by the association of permanent neonatal or early-infancy insulin-dependent diabetes, multiple epiphyseal dysplasia and growth retardation, and other variable multisystemic clinical manifestations. Based on genetic studies of two inbred families, we previously identified the gene responsible for this disorder as EIF2AK3, the pancreatic eukaryotic initiation factor 2alpha (eIF2alpha) kinase. Here, we have studied 12 families with WRS, totalling 18 cases. With the exception of one case, all patients carried EIF2AK3 mutations resulting in truncated or missense versions of the protein. Exclusion of EIF2AK3 mutations in the one patient case was confirmed by both linkage and sequence data. The activities of missense versions of EIF2AK3 were characterized in vivo and in vitro and found to have a complete lack of activity in four mutant proteins and residual kinase activity in one. Remarkably, the onset of diabetes was relatively late (30 months) in the patient expressing the partially defective EIF2AK3 mutant and in the patient with no EIF2AK3 involvement (18 months) compared with other patients (<6 months). The patient with no EIF2AK3 involvement did not have any of the other variable clinical manifestations associated with WRS, which supports the idea that the genetic heterogeneity between this variant form of WRS and EIF2AK3 WRS correlates with some clinical heterogeneity.

Impact of disordered puberty on bone density in beta-thalassaemia major.

Reduction of bone density and its associated morbidity is recognized in young adults with beta-thalassaemia major, but the aetiology is not clear. This study used dual X-ray absorptiometry (DXA) to look at bone mineral apparent density (BMAD) in children and young adults with thalassaemia in a predominantly Asian population, in the context of sexual maturation. Fifty-five patients were scanned (mean age 13.8 years, range 5.9-37.5) and BMAD z-scores were calculated using normal data from locally recruited control subjects. Eighteen patients had undergone bone marrow transplantation (BMT) and the remainder were on a transfusion/chelation regimen. BMAD z-scores ranged from -3.3-1.6 with a mean of -0.92. No difference in BMAD was found between those patients treated conventionally and those who had undergone BMT. When comparing mean BMAD z-score according to sexual maturation, there was a highly significant difference (P < 0.0001) between those whose pubertal maturation was age appropriate (mean z-score -0.22), when compared with those who had disordered puberty (mean z-score -1.82). We have shown that failure to progress normally through puberty is highly significant in the failure of adequate bone mineralization and achievement of peak bone mass in thalassaemic patients. The management of these patients should therefore be pro-active to anticipate problems and facilitate normal sexual maturation.