The IMPACT Survey: the economic impact of osteogenesis imperfecta in adults.

BACKGROUND: The IMPACT survey aimed to elucidate the humanistic, clinical and economic burden of osteogenesis imperfecta (OI) on individuals with OI, their families, caregivers and wider society. Research methodology, demographics and initial insights from the survey have been previously reported. The cost of illness (healthcare resource use, productivity loss, out-of-pocket spending) and drivers of the economic impact of OI are reported here. METHODS: IMPACT was an international mixed-methods online survey in eight languages (fielded July-September 2021) targeting adults (aged ≥ 18 years) or adolescents (aged ≥ 12-17 years) with OI, caregivers with or without OI and other close relatives. Survey domains included demographics, socioeconomic factors, clinical characteristics, treatment patterns, quality of life and health economics. The health economic domain for adults, which included questions on healthcare resource use, productivity loss and out-of-pocket spending, was summarised. Regression and pairwise analyses were conducted to identify independent drivers and associations with respondent characteristics. RESULTS: Overall, 1,440 adults with OI responded to the survey. Respondents were mostly female (70%) and from Europe (63%) with a median age of 43 years. Within a 12-month period, adults with OI reported visiting a wide range of healthcare professionals. Two-thirds (66%) of adults visited a hospital, and one-third (33%) visited the emergency department. The mean total number of diagnostic tests undergone by adults within these 12 months was 8.0. Adults had undergone a mean total of 11.8 surgeries up to the time point of the survey. The proportions of adults using queried consumables or services over 12 months ranged from 18-82%, depending on the type of consumable or service. Most adults (58%) were in paid employment, of which nearly one-third (29%) reported missing a workday. Of the queried expenses, the mean total out-of-pocket spending in 4 weeks was €191. Respondent characteristics such as female sex, more severe self-reported OI and the experience of fractures were often associated with increased economic burden. CONCLUSION: IMPACT provides novel insights into the substantial cost of illness associated with OI on individuals, healthcare systems and society at large. Future analyses will provide insights into country-specific economic impact, humanistic impact and the healthcare journey of individuals with OI.

Molecular Genetic Diagnosis with Targeted Next Generation Sequencing in a Cohort of Turkish Osteogenesis Imperfecta Patients and Their Genotype-phenotype Correlation.

Introduction: Osteogenesis imperfecta (OI) is a group of phenotypically and genetically heterogeneous connective tissue disorders that share similar skeletal anomalies causing bone fragility and deformation. This study aimed to investigate the molecular genetic etiology and determine the relationship between genotype and phenotype in OI patients with targeted next-generation sequencing (NGS). Method: In patients with OI, a targeted NGS analysis panel (Illumina TruSight One) containing genes involved in collagen/bone synthesis was performed on the Illumina Nextseq550 platform. Results: Fifty-six patients (female/male: 25/31) from 46 different families were enrolled in the study. Consanguinity between parents was noted in 15 (32.6%) families. Clinically according to Sillence classification; 18(33.1%) patients were considered to type I, 1(1.7%) type II, 26(46.4%) type III and 11(19.6%) type IV. Median body weight was -1.1 (-6.8, - 2.5) SDS, and height was -2.3 (-7.6, - 1.2) SDS. Bone deformity was detected in 30 (53.5%) of the patients, while 31 (55.4%) were evaluated as mobile. Thirty-six (60.7%) patients had blue sclera, 13 (23.2%) had scoliosis, 12 (21.4%) had dentinogenesis imperfecta (DI), and 2 (3.6%) had hearing loss. Disease-causing variants in COL1A1 and COL1A2 genes were found in 24 (52.1%) and 6 (13%) families, respectively. In 8 (17.3%) of the remaining 16 (34.7%) families, the NGS panel revealed disease-causing variants in three different genes (FKBP10, SERPINF1, and P3H1). Nine (23.6%) of the variants detected in all investigated genes were not previously reported in the literature and were classified to be pathogenic according to ACMG guidelines pathogenity scores. In ten (21.7%) families, a disease-related variant was not found in a total of 13 OI genes included in the panel. Conclusion: Genetic etiology was found in 38 (82.6%) of 46 families by targeted NGS analysis. In addition, 9 new variants were assessed in known OI genes which is a significant contribution to the literature.

Osteogenesis Imperfecta: Skeletal and Non-skeletal Challenges in Adulthood.

Osteogenesis imperfecta (OI) is a Mendelian connective tissue disorder associated with increased bone fragility and other clinical manifestations most commonly due to abnormalities in production, structure, or post-translational modification of type I collagen. Until recently, most research in OI has focused on the pediatric population and much less attention has been directed at the effects of OI in the adult population. This is a narrative review of the literature focusing on the skeletal as well as non-skeletal manifestations in adults with OI that may affect the aging individual. We found evidence to suggest that OI is a systemic disease which involves not only the skeleton, but also the cardiopulmonary and gastrointestinal system, soft tissues, tendons, muscle, and joints, hearing, eyesight, dental health, and women's health in OI and potentially adds negative affect to health-related quality of life. We aim to guide clinicians as well as draw attention to obvious knowledge gaps and the need for further research in adult OI.

Management of Combined Fracture Neck of Femur and Femoral Deformity in Osteogenesis Imperfecta Patient: A Case Report.

Osteogenesis imperfecta (OI) patients usually sustain repeated fractures from trivial trauma and also have skeletal deformities that affect walking. The bone fragility and repeated fractures produce deformities of the long bones especially in femur and tibia. However, neck of femur (NOF) fractures in OI are rarely described. A 11-year-old male patient known to have OI (Sillence type IV) sustained a NOF fracture after a fall. He also had proximal femoral anterolateral bowing proximally and over an intramedullary (IM) rod inserted 4 years back. He was treated by corrective osteotomy and stabilisation with an IM telescoping nail for the deformed femur and the Wagner technique for the NOF fracture. One year after operation, the patient had recovered satisfactory functional outcome with union of the NOF fracture and correction of the femoral deformity. Conclusion: The method of the Wagner technique can achieve stable fixation for femoral neck fractures and introduces the least interference with concurrent telescoping nail insertion. How to cite this article: Elbaseet HM, Ibrahim AH, Abol Oyoun N, et al. Management of Combined Fracture Neck of Femur and Femoral Deformity in Osteogenesis Imperfecta Patient: A Case Report. Strategies Trauma Limb Reconstr 2024;19(1):56-59.

Optimising Health-Related Quality of Life in Children With Osteogenesis Imperfecta.

Osteogenesis Imperfecta is a rare, hereditary bone condition with an incidence of 1/15,000-20,000. Symptoms include bone fragility, long bone deformity, scoliosis, hypermobility, alongside secondary features such as short stature, basilar invagination, pulmonary and cardiac complications, hearing loss, dentinogenesis imperfecta and malocclusion. Osteogenesis Imperfecta can have a large impact on the child and their family; this impact starts immediately after diagnosis. Fractures, pain, immobility, hospital admissions and the need for equipment and adaptations all influence the health-related quality of life of the individual and their family. This narrative review article aims to examine the impact the diagnosis and management of osteogenesis imperfecta has on the health-related quality of life of a child. It will touch on the effect this may have on the quality of life of their wider family and friends and identify strategies to optimise health-related quality of life in this population. Optimising health-related quality of life in children with Osteogenesis Imperfecta is often a complicated, multifaceted journey that involves the child, their extended family, school, extracurricular staff and numerous health professionals.

Rare coexistence of hypopituitarism with osteogenesis imperfecta - A double-trouble for bone.

Osteogenesis imperfecta (OI) commonly involving defects in COL1A1 and COL1A2 is a rare hereditary disease of bone fragility affecting 6-7 per 100,000 population. On the other hand, hypopituitarism is a separate entity that manifests with reduced levels of pituitary hormones. The cooccurrence of these two is seldom reported previously in literature as a deviation from Occam's razor. Here, we reported a case of pathological fracture in a 31-year-old male who had blue sclera and secondary adrenal insufficiency, hypogonadotropic hypogonadism, and growth hormone deficiency along with primary autoimmune hypothyroidism. Diagnosis of OI was suggested by heterozygous missense variant in exon 40 of the COL1A2 gene (chr7: g.94423092G > A; Depth: 99×) that resulted in the amino acid substitution of Serine for Glycine at codon 847. Replacement of glucocorticoid, levothyroxine, and testosterone was started along with antiresorptive therapy for better bone health outcomes.

Pseudoarthrosis of the Distal Humerus in Pediatric Osteogenesis Imperfecta Patients: A Case Series and Literature Review.

Osteogenesis imperfecta (OI) is a rare skeletal disorder that increases a patient's susceptibility to bone fracture. One complication commonly associated with fractures in this population is the occurrence of non-union leading to pseudoarthrosis. In this case series, three cases of non-union of the distal humerus leading to pseudoarthrosis in the pediatric OI population are presented. One case presents a successful attempt at treatment, one case presents a failed attempt at treatment, and the third case presents a patient's refusal to get treated. Furthermore, a literature review highlighting other institutions' attempts, successes, and failures at treating this clinical entity is presented. Combining the data retrieved from our institution and others, this review demonstrates that there is currently no standard for treating these patients. Additionally, based on the small case series and literature review presented in this article, definitive guidelines for the treatment of pseudoarthrosis of the distal humerus in pediatric OI patients cannot be outlined. However, our findings suggest that both non-surgical and surgical treatments could be viable options for patients with asymptomatic pseudoarthrosis of the distal humerus.

A case of osteogenesis imperfecta diagnosed after subchondral insufficiency fracture of bilateral femoral heads.

Osteogenesis imperfecta (OI) is a heterogeneous disorder characterised by bone fragility. Herein, we report a case of OI diagnosed after subchondral insufficiency fracture (SIF) of bilateral femoral heads. A 37-year-old woman was referred to Saitama Medical University Hospital due to left hip pain without any trauma that lasted for 2 months. She was subsequently diagnosed with SIF of the left femoral head. After 3 months, she further developed SIF of the right hip without any trauma. Magnetic resonance imaging of the bilateral hips showed linear low-signal changes of the subchondral bone and bone marrow oedema of the femoral head on T2-weighted coronal and sagittal images, diagnosing of both SIFs. The bone mineral density was 0.851 g/cm2 (T-score, -1.3) at the lumbar spine, 0.578 g/cm2 (T-score, -1.9) at the right femoral neck, and 0.582 g/cm2 (T-score, -1.9) at the left femoral neck. Considering that the patient had multiple histories of fracture, blue sclera, and mild bilateral sensorineural hearing loss, she satisfied the diagnostic criteria for OI. Genetic testing revealed a mutation in COL1A1 (NM_000088.3, c.3806G>A: p. Trp1269*). After 7 months of conservative therapy, her symptoms improved. After 4 years, both hips were pain-free with no evidence of osteoarthritis progression. OI can result in insufficiency fractures due to bone fragility in adolescence and adulthood or later, and none of the cases of OI, except for the current case, were diagnosed as a result of bilateral SIF.

Exome Sequencing for the Diagnostics of Osteogenesis Imperfecta in Six Russian Patients.

Osteogenesis imperfecta (OI) is a group of inherited disorders of connective tissue that cause significant deformities and fragility in bones. Most cases of OI are associated with pathogenic variants in collagen type I genes and are characterized by pronounced polymorphisms in clinical manifestations and the absence of clear phenotype-genotype correlation. The objective of this study was to conduct a comprehensive molecular-genetic and clinical analysis to verify the diagnosis of OI in six Russian patients with genetic variants in the COL1A1 and COL1A2 genes. Clinical and laboratory data were obtained from six OI patients who were observed at the Medical Genetics Center in Saint Petersburg from 2016 to 2023. Next-generation sequencing on MGISEQ G400 (MGI, China) was used for DNA analysis. The GATK bioinformatic software (version 4.5.0.0) was used for variant calling and hard filtering. Genetic variants were verified by the direct automatic sequencing of PCR products using the ABI 3500X sequencer. We identified six genetic variants, as follows pathogenic c.3505G>A (p. Gly1169Ser), c.769G>A (p.Gly257Arg), VUS c.4123G>A (p.Ala1375Thr), and c.4114A>T (p.Asn1372Tyr) in COL1A1; and likely pathogenic c.2035G>A (p.Gly679Ser) and c.739-2A>T in COL1A2. In addition, clinical cases are presented due to the presence of the c.4114A>T variant in the COL1A2 gene. Molecular genetics is essential for determining different OI types due to the high similarity across various types of the disease and the failure of unambiguous diagnosis based on clinical manifestations alone. Considering the variable approaches to OI classification, an integrated strategy is required for optimal patient management.

Caregiver Burden, Parenting Stress and Coping Strategies: The Experience of Parents of Children and Adolescents with Osteogenesis Imperfecta.

Only a few studies, mainly qualitative thematic analyses of interviews, have dealt with the psychological experience of parents of children and adolescents with osteogenesis imperfecta (OI), a rare genetic syndrome involving skeletal fragility and increased exposure to bone fractures. The aim of the present study was to evaluate both negative (i.e., parental burden and parenting stress) and positive (i.e., coping strategies and perceived social support) experiences of parents related to their children's disease and behaviour. The participants were 34 parents of children and adolescents with OI who completed a specifically developed online survey assessing their psychological experience with caregiving, their perception of the severity level of their children's condition and any possible behavioural problems experienced by their children. Data analyses showed that 65% of the parents showed a clinical level of caregiver burden and nearly 30% a clinical level of parenting stress. Caregiver burden was related to the perceived severity level of the condition and the externalising problems shown by their children. Concerning the positive aspects of the parents' experience, a high level of perceived social support was connected to a lower level of parenting stress; the same did not happen for caregiver burden. Coping strategies were connected to stress and burden; in particular, a higher level of stress corresponded to a higher level of avoidance, and a higher level of burden corresponded to a higher level of positive attitude.

Galunisertib downregulates mutant type I collagen expression and promotes MSCs osteogenesis in pediatric osteogenesis imperfecta.

Qualitative alterations in type I collagen due to pathogenic variants in the COL1A1 or COL1A2 genes, result in moderate and severe Osteogenesis Imperfecta (OI), a rare disease characterized by bone fragility. The TGF-ß signaling pathway is overactive in OI patients and certain OI mouse models, and inhibition of TGF-ß through anti-TGF-ß monoclonal antibody therapy in phase I clinical trials in OI adults is rendering encouraging results. However, the impact of TGF-ß inhibition on osteogenic differentiation of mesenchymal stem cells from OI patients (OI-MSCs) is unknown. The following study demonstrates that pediatric skeletal OI-MSCs have imbalanced osteogenesis favoring the osteogenic commitment. Galunisertib, a small molecule inhibitor (SMI) that targets the TGF-ß receptor I (TßRI), favored the final osteogenic maturation of OI-MSCs. Mechanistically, galunisertib downregulated type I collagen expression in OI-MSCs, with greater impact on mutant type I collagen, and concomitantly, modulated the expression of unfolded protein response (UPR) and autophagy markers. In vivo, galunisertib improved trabecular bone parameters only in female oim/oim mice. These results further suggest that type I collagen is a tunable target within the bone ECM that deserves investigation and that the SMI, galunisertib, is a promising new candidate for the anti-TGF-ß targeting for the treatment of OI.

Musculoskeletal System and Gait Characteristics in Patients with Osteogenesis imperfecta.

OBJECTIVES: The aim of the study was to assess the muscoloskeletal system and spatiotemporal gait parameters of patients in three types of osteogenesis imperfecta. DESIGN STUDY: Retrospective observational study. SETTINGS: The Department of Rehabilitation, Children's Memorial Health Institute in Warsaw, Poland. PARTICIPANTS: This study investigated individuals with various types of osteogenesis imperfecta: 33 with osteogenesis imperfecta I (aged 13.9), 16 with osteogenesis imperfecta III (aged 10.4), and 14 with osteogenesis imperfecta IV (aged, 15.8), as well as a reference group of 400 healthy individuals. MAIN MEASURES: The musculoskeletal assessment included: medical record review, clinical evaluation, functional tests, long bone deformity assessment via clinical and X-ray examination, and objective gait analysis with the Vicon Motion Systems (Ltd, Oxford, UK). RESULTS: The study revealed notable differences in clinical presentation, deformities within the musculoskeletal system, gait parameters across the various types of osteogenesis imperfecta (p < 0.001). The most affected gait parameters were: cadence, gait speed and step length. The greatest deformities of lower limbs and spine were presented in patients with osteogenesis imperfecta type III. CONCLUSIONS: These findings are significant for understanding gait abnormalities in osteogenesis imperfecta patients and designing customized physiotherapy programs to help them participate fully in daily life. Improvement of muscle strength is one of the key for easier engagement in activities like walking or stair-climbing.

Craniofacial dysmorphism of osteogenesis imperfecta mouse and effect of cathepsin K knockout: Preliminary craniometry observations.

OBJECTIVES: In addition to bone fragility, patients with osteogenesis imperfecta (OI) type III have typical craniofacial abnormalities, such as a triangular face and maxillary micrognathism. However, in the osteogenesis imperfecta mouse (oim), a validated model of OI type III, few descriptions exist of craniofacial phenotype. Treatment of OI mostly consists of bisphosphonate administration. Cathepsin K inhibition has been tested as a promising therapeutic approach for osteoporosis and positive results were observed in long bones of cathepsin K knocked out oim (oim/CatK-/-). This craniometry study aimed to highlight the craniofacial characteristics of oim and Cathepsin K KO mouse. MATERIALS AND METHODS: We analyzed the craniofacial skeleton of 51 mice distributed in 4 genotype groups: Wt (control), oim, CatK-/-, oim/CatK-/-. The mice were euthanized at 13 weeks and their heads were analyzed using densitometric (pQCT), X-ray cephalometric, and histomorphometric methods. RESULTS: The craniofacial skeleton of the oim mouse is frailer than the Wt one, with a reduced thickness and mineral density of the cranial vault and mandibular ramus. Different cephalometric data attest a dysmorphism similar to the one observed in humans with OI type III. Those abnormalities were not improved in the oim/CatK-/- group. CONCLUSION: These results suggest that oim mouse could serve as a complete model of the human OI type III, including the craniofacial skeleton. They also suggest that invalidation of cathepsin K has no impact on the craniofacial abnormalities of the oim model.

Perioperative Evaluation and Management of Children with Osteoporosis and Low Bone Mineral Density.

As medical and surgical treatment options for children with osteoporosis expand, multidisciplinary strategies for bone health optimization become more important. Each patient's bone mineral density and fracture history should be interpreted in context. Off-label bisphosphonate use is a standard pharmacologic intervention for children with osteoporosis for optimal bone accrual. It is possible to continue this therapy perioperatively under certain circumstances. The rare side effects (osteonecrosis of the jaw and atypical femur fractures) seem less common in children. Physical therapy, vitamin D supplementation, and other interventions are also important tools for optimal bone health perioperatively and for satisfactory surgical outcomes.

Dickkopf-1 (DKK1) blockade mitigates osteogenesis imperfecta (OI) related bone disease.

BACKGROUND: The current treatment of osteogenesis imperfecta (OI) is imperfect. Our study thus delves into the potential of using Dickkopf-1 antisense (DKK1-AS) to treat OI. METHODS: We analysed serum DKK1 levels and their correlation with lumbar spine and hip T-scores in OI patients. Comparative analyses were conducted involving bone marrow stromal cells (BMSCs) and bone tissues from wild-type mice, untreated OI mice, and OI mice treated with DKK1-ASor DKK1-sense (DKK1-S). RESULTS: Significant inverse correlations were noted between serum DKK1 levels and lumbar spine (correlation coefficient = - 0.679, p = 0.043) as well as hip T-scores (correlation coefficient = - 0.689, p = 0.042) in OI patients. DKK1-AS improved bone mineral density (p = 0.002), trabecular bone volume/total volume fraction (p < 0.001), trabecular separation (p = 0.010), trabecular thickness (p = 0.001), trabecular number (p < 0.001), and cortical thickness (p < 0.001) in OI mice. DKK1-AS enhanced the transcription of collagen 1α1, osteocalcin, runx2, and osterix in BMSC from OI mice (all p < 0.001), resulting in a higher von Kossa-stained matrix area (p < 0.001) in ex vivo osteogenesis assays. DKK1-AS also reduced osteoclast numbers (p < 0.001), increased ß-catenin and T-cell factor 4 immunostaining reactivity (both p < 0.001), enhanced mineral apposition rate and bone formation rate per bone surface (both p < 0.001), and decreased osteoclast area (p < 0.001) in OI mice. DKK1-AS upregulated osteoprotegerin and downregulated nuclear factor-kappa B ligand transcription (both p < 0.001). Bone tissues from OI mice treated with DKK1-AS exhibited significantly higher breaking force compared to untreated OI mice (p < 0.001). CONCLUSIONS: Our study elucidates that DKK1-AS has the capability to enhance bone mechanical properties, restore the transcription of osteogenic genes, promote osteogenesis, and inhibit osteoclastogenesis in OI mice.

Collagen mutation and age contribute to differential craniofacial phenotypes in mouse models of osteogenesis imperfecta.

Craniofacial and dentoalveolar abnormalities are present in all types of osteogenesis imperfecta (OI). Mouse models of the disorder are critical to understand these abnormalities and underlying OI pathogenesis. Previous studies on severely affected OI mice report a broad spectrum of craniofacial phenotypes, exhibiting some similarities to the human disorder. The Brtl/+ and G610c/+ are moderately severe and mild-type IV OI, respectively. Little is known about the aging effects on the craniofacial bones of these models and their homology to human OI. This study aimed to analyze the Brtl/+ and G610c/+ craniofacial morphometries during aging to establish suitability for further OI craniofacial bone intervention studies. We performed morphological measurements on the micro-CT-scanned heads of 3-wk-old, 3-mo-old, and 6-mo-old female Brtl/+ and G610c/+ mice. We observed that Brtl/+ skulls are shorter in length than WT (P < .05), whereas G610c/+ skulls are similar in length to their WT counterparts. The Brtl/+ mice exhibit alveolar bone with a porotic-like appearance that is not observed in G610c/+. As they age, Brtl/+ mice show severe bone resorption in both the maxilla and mandible (P < .05). By contrast, G610c/+ mice experience mandibular resorption consistently across all ages, but maxillary resorption is only evident at 6 mo (P < .05). Western blot shows high osteoclastic activities in the Brtl/+ maxilla. Both models exhibit delayed pre-functional eruptions of the third molars (P < .05), which are similar to those observed in some bisphosphonate-treated OI subjects. Our study shows that the Brtl/+ and G610c/+ mice display clear features found in type IV OI patients; both show age-related changes in the craniofacial growth phenotype. Therefore, understanding the craniofacial features of these models and how they age will allow us to select the most accurate mouse model, mouse age, and bone structure for the specific craniofacial bone treatment of differing OI groups.

Project SATURN- a real-world evidence data collaboration with existing European datasets in Osteogenesis Imperfecta to support future therapies.

Regulatory marketing authorisation is not enough to ensure patient access to new medicinal products. Health Technology Assessment bodies may require data on effectiveness, relative effectiveness, and cost-effectiveness. Healthcare systems may require data on clinical utility, savings, and budget impact. Furthermore, the exact requirements of these bodies vary country by country and sometimes even region to region, resulting in a patchwork of different data requirements to achieve effective, reimbursed patient access to new therapies. In addition, clinicians require data to make informed clinical management decisions. This requirement is of key importance in rare diseases where there is often limited data and clinical experience at the time of regulatory approval.This paper describes an innovative initiative that is called Project SATURN: Systematic Accumulation of Treatment practices and Utilization, Real world evidence, and Natural history data for the rare disease Osteogenesis Imperfecta. The objective of this project is to generate a common core dataset by utilising existing data sources to meet the needs of the various stakeholders and avoiding fragmentation through multiple approaches (e.g., a series of individual national requests/approaches, and unconnected with the regulators' potential requirements). It is expected that such an approach will reduce the time for patient access to life-changing medications. Whilst Project SATURN applies to Osteogenesis Imperfecta, it is anticipated that the principles could also be applied to other rare diseases and reduce the time for patient access to new medications.

IFITM5-related (type V) osteogenesis imperfecta with evidence of perinatal involvement: A case report.

Osteogenesis imperfecta (OI) is a rare hereditary disorder characterized by bone fragility and frequent fractures. While most cases are attributed to variations in collagen-coding genes COL1A1 and COL1A2, other genes such as IFITM5 have also been associated with the disease, accounting for up to 5 % of cases. Here, we report a case of a 3-month-old female with a femur fracture and limb deformity. X-rays revealed evidence of osteopenia and previous fractures in the arms, clavicle, ribs, and left limb, alongside prenatal bone deformities detected by ultrasound. Initial clinical evaluation suggested progressively deforming (Sillence's type III) osteogenesis imperfecta (OI). Molecular testing led to the diagnosis of IFITM5-related OI, identifying the c.-14C>T (rs587776916) variant. Although this variant has been previously reported in patients with IFITM5-related OI, prenatal involvement had not been associated with this variant.