Guidelines for Care of Adults With Down Syndrome

Woodward, Julie; Jan, Sophie; Ciccarelli, Mary

doi:10.1001/jama.2020.19150

Cited by 2 publications

(2 citation statements)

References 25 publications

(48 reference statements)

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“…Men and women with DS displayed lower BMD in the femoral neck and lumbar spine much earlier than individuals without DS, with men exhibiting bone loss around 20 years of age, and females experience rapid decline in BMD around 40 years of age [6,7,14]. A heretofore unidentified relationship between increased gene dosage of Hsa21 and perturbation of molecular pathways or cellular functions has been hypothesized [21,[24][25][26][27][28][29][30][31]. A report in a woman with DS that quantified the presence and number of bone cells, suggested an adynamic bone phenotype that lacked active osteoclasts [26].…”

Section: Development Of Skeletal Abnormalities In Individuals With Dsmentioning

confidence: 99%

“…1.5. Hypothesis; Reduction of Dyrk1a in Osteoblasts Will Improve Skeletal Deficits Associated with Ts21 in Ts65Dn Male and Female Mice Not much is known about specific causes of skeletal abnormalities in DS, and more information is needed to understand when these deficits appear, possible genes related to altered skeletal development, and how skeletal phenotypes present differently in males and females with DS [29]. Based on previous work, we proposed that Dyrk1a over-expression at or before 6 weeks would cause attenuated osteoblast function, leading to reduced bone formation and low bone mass compared to euploid control animals [31].…”

Section: Associated Skeletal Abnormalities From Ds Mouse Modelsmentioning

confidence: 99%

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Skeletal Deficits in Male and Female down Syndrome Model Mice Arise Independent of Normalized Dyrk1a Expression in Osteoblasts

Thomas

Sloan

Cave

et al. 2021

Genes

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Trisomy 21 (Ts21) causes alterations in skeletal development resulting in decreased bone mass, shortened stature and weaker bones in individuals with Down syndrome (DS). There is a sexual dimorphism in bone mineral density (BMD) deficits associated with DS with males displaying earlier deficits than females. The relationships between causative trisomic genes, cellular mechanisms, and influence of sex in DS skeletal abnormalities remain unknown. One hypothesis is that the low bone turnover phenotype observed in DS results from attenuated osteoblast function, contributing to impaired trabecular architecture, altered cortical geometry, and decreased mineralization. DYRK1A, found in three copies in humans with DS, Ts65Dn, and Dp1Tyb DS model mice, has been implicated in the development of postnatal skeletal phenotypes associated with DS. Reduced copy number of Dyrk1a to euploid levels from conception in an otherwise trisomic Ts65Dn mice resulted in a rescue of appendicular bone deficits, suggesting DYRK1A contributes to skeletal development and homeostasis. We hypothesized that reduction of Dyrk1a copy number in trisomic osteoblasts would improve cellular function and resultant skeletal structural anomalies in trisomic mice. Female mice with a floxed Dyrk1a gene (Ts65Dn,Dyrk1afl/wt) were mated with male Osx-Cre+ (expressed in osteoblasts beginning around E13.5) mice, resulting in reduced Dyrk1a copy number in mature osteoblasts in Ts65Dn,Dyrk1a+/+/Osx-Cre P42 male and female trisomic and euploid mice, compared with littermate controls. Male and female Ts65Dn,Dyrk1a+/+/+ (3 copies of DYRK1A in osteoblasts) and Ts65Dn,Dyrk1a+/+/Osx-Cre (2 copies of Dyrk1a in osteoblasts) displayed similar defects in both trabecular architecture and cortical geometry, with no improvements with reduced Dyrk1a in osteoblasts. This suggests that trisomic DYRK1A does not affect osteoblast function in a cell-autonomous manner at or before P42. Although male Dp1Tyb and Ts65Dn mice exhibit similar skeletal deficits at P42 in both trabecular and cortical bone compartments between euploid and trisomic mice, female Ts65Dn mice exhibit significant cortical and trabecular deficits at P42, in contrast to an absence of genotype effect in female Dp1Tyb mice in trabecular bone. Taken together, these data suggest skeletal deficits in DS mouse models and are sex and age dependent, and influenced by strain effects, but are not solely caused by the overexpression of Dyrk1a in osteoblasts. Identifying molecular and cellular mechanisms, disrupted by gene dosage imbalance, that are involved in the development of skeletal phenotypes associated with DS could help to design therapies to rescue skeletal deficiencies seen in DS.

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