Antiepileptic medications increase osteoporosis risk in male fabry patients: bone mineral density in an Australian cohort

Assessing osteopenia and osteoporosis with dual-energy x-ray absorptiometry studies in Fabry disease

BACKGROUND

Fabry disease (FD) is a rare multi-systemic lysosomal storage disease that affects the heart and kidneys most significantly. An underappreciated manifestation of FD is reduced bone mineral density. Currently, there are no specific guidelines for routine bone density assessments, and treatment of osteoporosis and osteopenia in FD.

MATERIALS AND METHODS

To ascertain the frequency of low bone mineral density in FD we studied dual-energy x-ray absorptiometry (DXA) scans obtained as part of routine care from a cohort of 25 individuals followed at the University of California-Irvine Medical Center for the period 2008-2023. The most recent BMD results for the lumbar spine and femoral neck were collected from 12 males and 13 females to examine the prevalence of low bone mineral density. The lowest Z- and/or T-scores of either lumbar spine or femoral neck were selected for analysis. Demographic factors, disease and ERT status, and other laboratory values were collected concurrently (within ± 9 months) with DXA scan results and were analyzed with Z- and T-scores to assess for correlations. In our cohort the mean age was 51 years (median 56 years, range 18-77 years). The Z-scores for all participants and T-scores from postmenopausal women and men ≥ 50-year-old were analyzed and correlated with various measures including disease duration, BMI, renal function (measured by eGFR), plasma GL3, Lyso-GL3, calcium, vitamin D, and alkaline phosphatase levels. These parameters were concurrent with DXA scan results.

RESULTS

The average Z-score for all the participants was -1.2 ± 1.3 (range -4.6 to 1.6). Twenty-four percent of all participants (n = 6) had significantly low Z-scores ≤ -2.0. To identify the frequency of subjects with osteopenia, defined as T-score between -1.0 and -2.5 and osteoporosis defined as T-score < -2.5, T-scores were analyzed in postmenopausal women (n = 8) and men 50 years and older (n = 7). Of these 15 individuals, average T-score was -2.2 ± 1.3 (range -5.4 to 0.3), and 86.7% (n = 13) had abnormal results (osteopenia and osteoporosis), 53.3% (n = 8) had osteoporosis and 33.3% (n = 5) had osteoporosis. We found a significant difference in Z-scores between male (-1.98 ± 1.33) and female patients (-.45 ± 0.82) t (23) = 3.487 (p =  < 0.001). We did not find any differences in z-scores between different ethnic backgrounds. There was a strong negative correlation between Z-scores and Lyso-GL3 levels [r (15) = -.72, p = .001] and a moderate positive correlation between Z-scores and body mass index (BMI) [r (23) = .43, p = .033]. No correlation was found between Z-scores and calcium levels. There is a strong negative correlation between T-scores and Lyso-GL3 levels [r (8) = -.86, p = .001] and a negative correlation between T-scores and participants' ages at the time of DXA [r (13) = -.57, p = 0.028]. There is a positive correlation between T- scores and calcium levels [r (12) = .58, p = 0.030]. No significant correlation was observed between T-scores and BMI. There was no correlation between Z or T- scores and disease duration, duration of ERT use, renal function (measured by eGFR), GL3, creatinine, alkaline phosphatase levels, or their use of vitamin D or concomitant antiepileptic medications.

CONCLUSION

The findings of this cohort highlight the high prevalence of low bone mineral density in FD and correlations of low Z and T- scores with elevated levels of Lyso-GL3, and low calcium levels. We did not find correlations with renal function, and vitamin D levels. We discuss etiology, prevention, and treatment strategies for osteopenia/osteoporosis in Fabry disease.

Decreased trabecular bone score in patients affected by Fabry disease

BACKGROUND

Fabry disease (FD) is an inherited X-linked lysosomal storage disease characterized by increased risk of osteoporosis and fractures. The impact of FD on clinical measures of bone quality is unknown. This considered, aim of our study was to evaluate whether trabecular bone microarchitecture, measured by trabecular bone score (TBS), is altered in patients with FD compared to control subjects.

METHODS

This retrospective monocentric study enrolled 14 patients (M/F 1/1, median age 46 [37-63] years, range 31-72 years) newly diagnosed with FD between January 2016 and July 2023 who underwent dual-energy X-ray absorptiometry (DXA) image at the time of diagnosis and 42 matched controls. In all subjects, data about bone mineral density (BMD) and lumbar spine TBS were collected and total calcium, parathyroid hormone (PTH), 25(OH) vitamin D, alkaline phosphatase (ALP), creatinine and estimated glomerular filtration rate (eGFR) were evaluated. In subjects with FD, globotriaosylsphingosine (lyso-Gb3), 24-hour proteinuria and albumin-creatinine ratio were also assessed.

RESULTS

Patients with FD presented significantly lower lumbar spine TBS (1.29 [1.22-1.38] vs. 1.42 [1.39-1.47], p < 0.001) and lower lumbar spine BMD (0.916 ± 0.166 vs. 1.031 ± 0.125 g/cm2, p = 0.008) compared to controls; moreover, FD was shown to be an independent risk factor for both low lumbar spine TBS (β = -0.118, p < 0.001) and BMD (β = -0.115, p = 0.009). No differences were found in serum calcium, ALP, 25(OH) vitamin D and eGFR in both groups, but FD patients had significantly higher PTH levels compared to controls (p = 0.016). Finally, 8 patients with FD presented either moderately or severely increased albuminuria and only 2 patients presented normal lyso-Gb3 levels.

CONCLUSION

Patients affected by FD present significantly lower lumbar spine TBS and BMD compared to controls. Our findings strongly support the importance of carrying out a thorough evaluation of bone status in all patients affected by FD at baseline.

The Effect of Fabry Disease Therapy on Bone Mineral Density

Fabry disease (FD) is an X-linked lysosomal storage disorder, characterised by the cellular accumulation of globotriaosylceramide due to impaired alpha-galactosidase A enzyme activity. FD may manifest with multisystem pathology, including reduced bone mineral density (BMD). Registry data suggest that the introduction of Fabry-specific therapies (enzyme replacement therapy or chaperone therapy) has led to significant improvements in overall patient outcomes; however, there are limited data on the impact on bone density. The aim of this study was to describe the effect of Fabry-specific therapies on longitudinal changes in bone mineral density (BMD) in FD. We performed a retrospective observational study analysing bone densitometry (DXA) in patients with genetically confirmed FD. Patients were grouped based on the use of Fabry-specific therapies. The between-group longitudinal change in BMD Z-score was analysed using linear mixed effects models. A total of 88 FD patients were analysed (50 untreated; 38 treated). The mean age at first DXA was 38.5 years in the untreated group (84% female) and 43.7 years in the treated group (34% female). There was no significant longitudinal between-group difference in the BMD Z-score at the lumbar spine. However, the Z-score per year at the total hip (β = -0.105, p < 0.001) and femoral neck (β = -0.081, p = 0.001) was significantly lower over time in the treated than the untreated group. This may reflect those receiving therapy having a more severe underlying disease. Nevertheless, this suggests that Fabry-specific therapies do not reverse all disease mechanisms and that the additional management of BMD may be required in this patient population.

Investigation of bone mineral density and the changes by enzyme replacement therapy in patients with Fabry disease

BACKGROUND

Fabry disease (FD) is an inherited disorder that causes organ dysfunction. However, only a few studies have reported on bone mineral density (BMD) in FD patients, and the relationship between BMD and clinical factors such as globotriaosylsphingosine (lyso-Gb3) remains unclear. Therefore, the current study sought to investigate BMD in FD patients, the relationship between BMD and lyso-Gb3, and the effects of enzyme replacement therapy (ERT) on changes in BMD and lyso-Gb3.

METHODS

This single-center, observational study included 15 patients who visited our facility for FD between January 2008 and June 2021. We assessed BMD and clinical characteristics in study patients, including plasma lyso-Gb3 levels, and examined the relationship between BMD and plasma lyso-Gb3 levels, and changes in BMD after starting ERT.

RESULTS

Male patients' BMD had reduced, whereas female patients' BMD was preserved. Male patients had significantly higher plasma lyso-Gb3 levels than female patients. Moreover, plasma lyso-Gb3 levels were found to be significantly related to the lumbar spine and femoral BMD. These were strongly linked with plasma lyso-Gb3 levels in male patients, whereas no strong link was observed in female patients. Furthermore, BMD significantly increased only in male patients although plasma lyso-Gb3 levels significantly decreased by ERT in all patients.

CONCLUSION

BMD decreased possibly due to Gb3 accumulation, and ERT could increase BMD in male FD patients.

Reduced hip bone mineral density is associated with high levels of calciprotein particles in patients with Fabry disease

Calciprotein particles (CPP) are nanoscale mineralo-protein aggregates that help stabilize excess mineral in the circulation. We examined the relationship between CPP and bone mineral density in Fabry disease patients. We found an inverse correlation with total hip and femoral neck density, but none with lumbar spine.

PURPOSE

Calciprotein particles (CPP) are colloidal mineral-protein complexes made up primarily of the circulating glycoprotein fetuin-A, calcium, and phosphate. They form in extracellular fluid and facilitate the stabilization, transport, and clearance of excess minerals from the circulation. While most are monomers, they also exist in larger primary (CPP-I) and secondary (CPP-II) form, both of which are reported to be raised in pathological states. This study sought to investigate CPP levels in the serum of patients with Fabry disease, an X-linked systemic lysosomal storage disorder that is associated with generalized inflammation and low bone mineral density (BMD).

METHODS

We compared serum CPP-I and CPP-II levels in 59 patients with Fabry disease (37 female) with levels in an age-matched healthy adult cohort (n=28) and evaluated their association with BMD and biochemical data obtained from routine clinical review.

RESULTS

CPP-I and CPP-II levels were higher in male Fabry disease patients than female sufferers as well as their corresponding sex- and age-matched controls. CPP-II levels were inversely correlated with BMD at the total hip and femoral neck, but not the lumbar spine. Regression analyses revealed that these associations were independent of common determinants of BMD, but at the femoral neck, a significant association was only found in female patients.

CONCLUSION

Low hip BMD was associated with high CPP-II in patients with Fabry disease, but further work is needed to investigate the relevance of sex-related differences and to establish whether CPP measurement may aid assessment of bone disease in this setting.

Low bone mineral density due to secondary hyperparathyroidism in the GlatmTg(CAG-A4GALT) mouse model of Fabry disease

Low bone mineral density (BMD)-diagnosed as osteoporosis or osteopenia-has been reported as a new characteristic feature of Fabry disease; however, the mechanism underlying the development of low BMD is unknown. We previously revealed that a mouse model of Fabry disease [GlatmTg(CAG-A4GALT)] exhibits impaired functioning of medullary thick ascending limb (mTAL), leading to insufficient Ca2+ reabsorption and hypercalciuria. Here, we investigated bone metabolism in GlatmTg(CAG-A4GALT) mice without marked glomerular or proximal tubular damage. Low BMD was detected by 20 weeks of age via micro-X-ray-computed tomography. Bone histomorphometry revealed that low BMD results by accelerated bone resorption and osteomalacia. Plasma parathyroid hormone levels increased in response to low blood Ca2+-not plasma fibroblast growth factor 23 (FGF-23) elevation-by 5 weeks of age and showed progressively increased phosphaturic action. Secondary hyperparathyroidism developed by 20 weeks of age and caused hyperphosphatemia, which increased plasma FGF-23 levels with phosphaturic action. The expression of 1α-hydroxylase [synthesis of 1α,25(OH)2D3] in the kidney did not decrease, but that of 24-hydroxylase [degradation of 1α,25(OH)2D3] decreased. Vitamin D deficiency was ruled out as the cause of osteomalacia, as plasma 1α,25(OH)2D3 and 25(OH)D3 levels were maintained. Results demonstrate that secondary hyperparathyroidism due to mTAL impairment causes accelerated bone resorption and osteomalacia due to hyperphosphaturia and hypercalciuria, leading to low BMD in Fabry model mice.

European expert consensus statement on therapeutic goals in Fabry disease

BACKGROUND

Fabry disease, an inherited lysosomal storage disorder, causes multi-organ pathology resulting in substantial morbidity and a reduced life expectancy. Although Fabry disease is an X-linked disorder, both genders may be affected, but generally to a lesser extent in females. The disease spectrum ranges from classic early-onset disease to non-classic later-onset phenotypes, with complications occurring in multiple organs or being confined to a single organ system depending on the stage of the disease. The impact of therapy depends upon patient- and disease-specific factors and timing of initiation.

METHODS

A European panel of experts collaborated to develop a set of organ-specific therapeutic goals for Fabry disease, based on evidence identified in a recent systematic literature review and consensus opinion.

RESULTS

A series of organ-specific treatment goals were developed. For each organ system, optimal treatment strategies accounted for inter-patient differences in disease severity, natural history, and treatment responses as well as the negative burden of therapy and the importance of multidisciplinary care. The consensus therapeutic goals and proposed patient management algorithm take into account the need for early disease-specific therapy to delay or slow the progression of disease as well as non-specific adjunctive therapies that prevent or treat the effects of organ damage on quality of life and long-term prognosis.

CONCLUSIONS

These consensus recommendations help advance Fabry disease management by considering the balance between anticipated clinical benefits and potential therapy-related challenges in order to facilitate individualized treatment, optimize patient care and improve quality of life.

Musculoskeletal manifestations of Fabry disease: A retrospective study

OBJECTIVES

Fabry disease is a rare X-linked metabolic disorder characterized by a deficiency in the enzyme alpha-galactosidase A. Both males and females can be affected. The main presenting symptom is pain in the extremities, whereas at a more advanced stage, the manifestations include hypertrophic cardiomyopathy, cardiac dysrhythmia, proteinuria, chronic kidney dysfunction, stroke, and hearing loss. When not diagnosed and treated, Fabry disease causes early death. No studies specifically designed to describe the musculoskeletal manifestations of Fabry disease are available.

METHODS

We conducted a single-center retrospective study of patients receiving follow-up at a Fabry disease referral center. We described the musculoskeletal manifestations and analyzed the differential diagnoses.

RESULTS

Our study included 40 patients belonging to 20 families, including 25 females with a mean age of 44.2 years (range, 20-76 years) and 15 males with a mean age of 40.1 years (range, 16-61 years). Mean age at the diagnosis of Fabry disease was 37.2 years (range, 7-71 years) in the females and 26.9 years (range, 9-51 years) in the males. Specific enzyme replacement therapy was given to 10 (40%) females and 12 (80%) males. Musculoskeletal manifestations were as follows: past or present pain in the extremities (13 females and 10 males), combined in some patients with vasomotor disorders in the extremities and telangiectasia; exercise intolerance (12 females and 12 males); osteoporotic fractures (2 brothers aged 45 and 44 years, respectively); osteoporosis (3 females, aged 57, 63, and 75 years, respectively), which contributed to death in the oldest patient; osteopenia (2 females aged 38 and 47 years, respectively; and 1 male aged 43 years); Charcot foot and lymphedema with serious infectious complications (4 males older than 40 years), with avascular osteonecrosis of the lower limbs in 2 cases; toe amputations (3 cases); bilateral lower-limb amputation (1 case); abnormally slender lower limbs (5 females and 8 males); acute gout (3 males with severe chronic kidney failure); and carpal tunnel syndrome (1 female and 1 male, both younger than 40 years). Mistaken diagnoses that were made at an early stage, contributing to delay the identification of Fabry disease, included rheumatic fever (2 females and 2 males), growing pains (2 males), pain with paralysis (1 female), chilblains of the lower limbs (1 female), and erythermalgia (1 female). In adulthood, the following mistaken diagnoses were made: Sjögren's syndrome and/or sicca syndrome (6 females), systemic sclerosis (1 male), dysautonomia (1 female), and familial Mediterranean fever (1 female).

CONCLUSION

The diagnosis of Fabry disease is usually delayed, due to confusion with more common disorders. Musculoskeletal manifestations may constitute the presenting symptoms. Past or present pain in the extremities is typical. Osteoporosis may develop early and become severe. Together with the family history, the presence of musculoskeletal manifestations can lead to the correct diagnosis by prompting alpha-galactosidase assays in males and genetic testing in females. Fabry disease is often responsible for musculoskeletal manifestations, of which the most common are pain in the extremities and osteoporosis. These manifestations can be inaugural and lead to diagnostic wanderings. They require specific treatment strategies.