Browsing by Author "Polgreen, Lynda E."

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    Autosomal Dominant Osteopetrosis
    (Elsevier, 2023) Polgreen, Lynda E.; Imel, Erik A.; Econs, Michael J.; Medicine, School of Medicine
    Autosomal dominant osteopetrosis (ADO) is the most common form of osteopetrosis. ADO is characterized by generalized osteosclerosis along with characteristic radiographic features such as a "bone-in-bone" appearance of long bones and sclerosis of the superior and inferior vertebral body endplates. Generalized osteosclerosis in ADO typically results from abnormalities in osteoclast function, due most commonly to mutations in the chloride channel 7 (CLCN7) gene. A variety of debilitating complications can occur over time due to bone fragility, impingement of cranial nerves, encroachment of osteopetrotic bone in the marrow space, and poor bone vascularity. There is a wide spectrum of disease phenotype, even within the same family. Currently, there is no disease specific treatment for ADO, so clinical care focuses on monitoring for disease complications and symptomatic treatment. This review describes the history of ADO, the wide disease phenotype, and potential new therapies.
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    Autosomal Dominant Osteopetrosis (ADO) Caused by a Missense Variant in the TCIRG1 Gene
    (Oxford University Press, 2024) Jodeh, Wade; Katz, Amy J.; Hart, Marian; Warden, Stuart J.; Niziolek, Paul; Alam, Imranul; Ing, Steven; Polgreen, Lynda E.; Imel, Erik A.; Econs, Michael J.; Medicine, School of Medicine
    Context: Autosomal dominant osteopetrosis (ADO) is a rare genetic disorder resulting from impaired osteoclastic bone resorption. Clinical manifestations frequently include fractures, osteonecrosis (particularly of the jaw or maxilla), osteomyelitis, blindness, and/or bone marrow failure. ADO usually results from heterozygous missense variants in the Chloride Channel 7 gene (CLCN7) that cause disease by a dominant negative mechanism. Variants in the T-cell immune regulator 1 gene (TCIRG1) are commonly identified in autosomal recessive osteopetrosis but have only been reported in 1 patient with ADO. Case description: Here, we report 3 family members with a single heterozygous missense variant (p.Gly579Arg) in TCIRG1 who have a phenotype consistent with ADO. Three of 5 protein prediction programs suggest this variant likely inhibits the function of TCIRG1. Conclusion: This is the first description of adult presentation of ADO caused by a TCIRG1 variant. Similar to families with ADO from CLCN7 mutations, this variant in TCIRG1 results in marked phenotype variability, with 2 subjects having severe disease and the third having very mild disease. This family report implicates TCIRG1 missense mutations as a cause of ADO and demonstrates that the marked phenotypic variability in ADO may extend to disease caused by TCIRG1 missense mutations.
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    Patient-Reported Outcomes in Autosomal Dominant Osteopetrosis: Findings From the Osteopetrosis Registry Study
    (Oxford University Press, 2025) Polgreen, Lynda E.; Villa-Lopez, Eva; Chen, Liz; Liu, Ziyue; Katz, Amy; Parks-Schenck, Corinne; Hart, Marian; Imel, Erik A.; Econs, Michael J.; Biostatistics and Health Data Science, Richard M. Fairbanks School of Public Health
    Context: Autosomal dominant osteopetrosis (ADO) is a rare sclerotic bone disease characterized by impaired osteoclast activity, resulting in high bone mineral density and skeletal fragility. The full phenotype and disease burden on patients' daily lives has not been systematically measured. Objective: We developed an online registry to ascertain population-based data on the spectrum and rate of progression of disease and to identify relevant patient-centered outcomes that could be used to measure treatment effects and guide the design of future clinical trials. Methods: Cross-sectional data from participants with osteopetrosis were collected using an online REDCap-based database. Thirty-four participants with a confirmed diagnosis of ADO, aged 4-84 years were included. Participants aged 18 years and older completed the PROMIS 57, participants aged 8-17 years completed the PROMIS Pediatric 49, and parents of participants aged <18 years completed the PROMIS Parent Proxy 49. Results: Based on the PROMIS 57, relative to the general population, adults with ADO reported low physical function and low ability to participate in social roles and activities, and high levels of anxiety, fatigue, sleep problems, and pain interference. Daily pain medications were reported by 24% of the adult population. In contrast, neither pediatric participants nor their parent proxy reported a negative impact on health-related quality of life. Conclusion: Data from this registry demonstrate the broad spectrum of ADO disease severity and high impact on health-related quality of life in adults with ADO.
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    Unusual Cortical Phenotype After Hematopoietic Stem Cell Transplantation in a Patient With Osteopetrosis
    (Wiley, 2022-04-29) Afshariyamchlou, Sonia; Ng, Michelle; Ferdjallah, Asmaa; Warden, Stuart J.; Niziolek, Paul; Alam, Imranul; Polgreen, Lynda E.; Imel, Erik A.; Orchard, Paul; Econs, Michael J.; Medicine, School of Medicine
    The osteopetroses are a group of rare genetic diseases caused by osteoclast dysfunction or absence. The hallmark of osteopetrosis is generalized increased bone mineral density (BMD). However, the bone is fragile and fractures are common. Autosomal recessive osteopetrosis is usually a severe disorder and often life-threatening in childhood. We present male siblings with autosomal recessive osteopetrosis due to biallelic variants in TCIRG1 who survived childhood and underwent hematopoietic stem cell transplant (HSCT) in adulthood. One sibling died of posttransplant complications. After transplant, the other sibling had improvement of multiple clinical parameters, including some decline in BMD Z-scores by dual-energy X-ray absorptiometry (DXA) and cessation of fractures. However, spine quantitative computed tomography 11 years after transplant demonstrated an anvil pattern of sclerosis with BMD Z-score of +18.3. High-resolution peripheral quantitative computed tomography (HR-pQCT) of the tibia demonstrated near complete obliteration of the marrow space combined with an unusual cortical phenotype, suggesting extensive cortical porosity at the distal tibia. This case highlights that despite successful transplantation and subsequent improvement in clinical parameters, this patient continued to have significantly elevated bone density and decreased marrow space. Transplant-associated increased cortical porosity is multifactorial and occurs in two-thirds of non-osteopetrotic patients undergoing HSCT. This finding after transplant in osteopetrosis may suggest particular sensitivity of the cortical bone to resorptive activity of transplanted osteoclasts. The case also suggests HR-pQCT may be a useful modality for imaging and assessing the therapeutic effects on bone in individuals with osteopetrosis.