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- Campos-Xavier, Ana Belinda, et al.
(author)
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Mutations in the heparan-sulfate proteoglycan glypican 6 (GPC6) impair endochondral ossification and cause recessive omodysplasia
- 2009
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In: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297 .- 1537-6605. ; 84:6, s. 760-70
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Journal article (peer-reviewed)abstract
- Glypicans are a family of glycosylphosphatidylinositol (GPI)-anchored, membrane-bound heparan sulfate (HS) proteoglycans. Their biological roles are only partly understood, although it is assumed that they modulate the activity of HS-binding growth factors. The involvement of glypicans in developmental morphogenesis and growth regulation has been highlighted by Drosophila mutants and by a human overgrowth syndrome with multiple malformations caused by glypican 3 mutations (Simpson-Golabi-Behmel syndrome). We now report that autosomal-recessive omodysplasia, a genetic condition characterized by short-limbed short stature, craniofacial dysmorphism, and variable developmental delay, maps to chromosome 13 (13q31.1-q32.2) and is caused by point mutations or by larger genomic rearrangements in glypican 6 (GPC6). All mutations cause truncation of the GPC6 protein and abolish both the HS-binding site and the GPI-bearing membrane-associated domain, and thus loss of function is predicted. Expression studies in microdissected mouse growth plate revealed expression of Gpc6 in proliferative chondrocytes. Thus, GPC6 seems to have a previously unsuspected role in endochondral ossification and skeletal growth, and its functional abrogation results in a short-limb phenotype.
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| 2. |
- Fredwall, Svein O., et al.
(author)
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Cardiovascular risk factors and body composition in adults with achondroplasia
- 2021
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In: Genetics in Medicine. - : SPRINGERNATURE. - 1098-3600 .- 1530-0366. ; 23, s. 732-739
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Journal article (peer-reviewed)abstract
- Purpose An increased cardiovascular mortality has been reported in achondroplasia. This population-based, case-control study investigated cardiovascular risk factors and body composition in Norwegian adults with achondroplasia. Methods We conducted anthropometric, clinical, and laboratory assessments in 49 participants with achondroplasia, of whom 40 completed magnetic resonance imaging (MRI) for body composition analysis. Controls consisted of 98 UK Biobank participants, matched for body mass index (BMI), sex, and age. Results Participants were well matched for BMI (33.3 versus 32.5 kg/m(2)) and sex, but achondroplasia participants were younger than controls (mean age 41.1 versus 54.3 years). Individuals with achondroplasia had lower age-adjusted mean blood pressure, total and low-density lipoprotein (LDL) cholesterol, and triglycerides compared with controls, but similar fasting glucose and HbA1c values. Age-adjusted mean visceral fat store was 1.9 versus 5.3 L (difference -2.7, 95% confidence interval [CI] -3.6 to -1.9; P < 0.001), abdominal subcutaneous fat was 6.0 versus 11.2 L (-4.7, 95% CI -5.9 to -3.4; P < 0.001), and liver fat was 2.2 versus 6.9% (-2.8, 95% CI -5.2 to -0.4; P = 0.02). Conclusion Despite a high BMI, the cardiovascular risks appeared similar or lower in achondroplasia compared with controls, indicating that other factors might contribute to the increased mortality observed in this condition.
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| 3. |
- Fredwall, Svein O., et al.
(author)
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Fat infiltration in the thigh muscles is associated with symptomatic spinal stenosis and reduced physical functioning in adults with achondroplasia
- 2023
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In: Orphanet Journal of Rare Diseases. - : BMC. - 1750-1172. ; 18:1
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Journal article (peer-reviewed)abstract
- BackgroundSymptomatic spinal stenosis is a prevalent complication in adults with achondroplasia. Increased muscle fat infiltration (MFI) and reduced thigh muscle volumes have also been reported, but the pathophysiology is poorly understood. We explored whether the increased MFI and reduced thigh muscle volumes were associated with the presence of symptomatic spinal stenosis and physical functioning.MethodsMFI and thigh muscle volumes were assessed by MRI in 40 adults with achondroplasia, and compared to 80 average-statured controls, matched for BMI, gender, and age. In achondroplasia participants, the six-minute walk-test (6MWT), the 30-s sit-to-stand test (30sSTS), and a questionnaire (the IPAQ) assessed physical functioning.ResultsSymptomatic spinal stenosis was present in 25 of the participants (the stenosis group), while 15 did not have stenosis (the non-stenosis group). In the stenosis group, 84% (21/25) had undergone at least one spinal decompression surgery. The stenosis group had significantly higher MFI than the non-stenosis group, with an age-, gender and BMI-adjusted difference in total MFI of 3.3 percentage points (pp) (95% confidence interval [CI] 0.04 to 6.3 pp; p = 0.03). Compared to matched controls, the mean age-adjusted difference was 3.3 pp (95% CI 1.7 to 4.9 pp; p < 0.01). The non-stenosis group had MFI similar to controls (age-adjusted difference - 0.9 pp, 95% CI - 3.4 to 1.8 pp; p = 0.51). MFI was strongly correlated with the 6MWT (r = - 0.81, - 0.83, and - 0.86; all p-values < 0.01), and moderately correlated with the 30sSTS (r = - 0.56, - 0.57, and - 0.59; all p-values < 0.01). There were no significant differences in muscle volumes or physical activity level between the stenosis group and the non-stenosis group.ConclusionIncreased MFI in the thigh muscles was associated with the presence of symptomatic spinal stenosis, reduced functional walking capacity, and reduced lower limb muscle strength. The causality between spinal stenosis, accumulation of thigh MFI, and surgical outcomes need further study. We have demonstrated that MRI might serve as an objective muscle biomarker in future achondroplasia studies, in addition to functional outcome measures. The method could potentially aid in optimizing the timing of spinal decompression surgery and in planning of post-surgery rehabilitation.
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