Low bone turnover and low bone density in a cohort of adults with Down syndrome

Bone status in genetic syndromes: a review

More and more data seem to indicate the presence of an increasing number of syndromes and genetic diseases characterized by impaired bone mass and quality. Meanwhile, the improvement of etiopathogenetic knowledge and the employment of more adequate treatments have generated a significant increase in survival related to these syndromes and diseases. It is thus important to identify and treat bone impairment in these patients in order to assure a better quality of life. This review provides an updated overview of bone pathophysiology and characteristics in patients with Down, Turner, Klinefelter, Marfan, Williams, Prader-Willi, Noonan, and 22q11 deletions syndrome. In addition, some options for the treatment of the bone status impairment in these patients will be briefly discussed.

Determinants of vitamin d levels in children and adolescents with down syndrome

Background. Poor studies have evaluated 25-hydroxycholecalciferol (25(OH)D) levels in Down syndrome (DS). Objective. To assess in DS subjects serum 25(OH)D value, to identify risk factors for vitamin D deficiency, and to evaluate whether a normal 25(OH)D value can be restored with a 400 I.U. daily supplement of cholecalciferol in respect to controls. Methods. We have longitudinally evaluated 31 DS patients (aged 4.5-18.9 years old) and 99 age- and sex-matched healthy controls. In these subjects, we analysed calcium, phosphate, parathyroid hormone (PTH), 25(OH)D concentrations, and calcium and 25(OH)D dietary intakes, and we quantified outdoor exposure. After 12.3 months (range 8.1-14.7 months) of 25(OH)D supplementation, we reevaluated these subjects. Results. DS subjects showed reduced 25(OH)D levels compared to controls (P < 0.0001), in particular DS subjects with obesity (P < 0.05) and autoimmune diseases history (P < 0.005). PTH levels were significantly higher in DS subjects than controls (P < 0.0001). After cholecalciferol supplementation, 25(OH)D levels were significantly ameliorated (P < 0.05), even if reduced compared to controls (P < 0.0001), in particular in DS subjects with obesity (P < 0.05) and autoimmune diseases (P < 0.001). Conclusions. Hypovitaminosis D is very frequent in DS subjects, in particular in presence of obesity and autoimmune diseases. In these subjects, there could be a need for higher cholecalciferol supplementation.

Characteristics of adults with down syndrome: prevalence of age-related conditions

INTRODUCTION

In the last decades, life expectancy of persons with Down syndrome (DS) has dramatically increased and it is estimated that they will be living as long as the general population within a generation. Despite being included among the progeroid syndromes, because of the presence of features typically observed in older adults, DS is still regarded as a disease of pediatric interest. Because limited knowledge is available on the clinical characteristics of adults with DS, this study aimed to assess clinical and non-clinical features of this population and to describe similarities to the geriatric population.

METHODS

In this study, we described 60 adults with DS evaluated at the Day Hospital of the Geriatric Department of the Policlinico A. Gemelli, Università Cattolica del Sacro Cuore in Rome. Individuals were assessed through a standardized protocol.

RESULTS

The mean age of study participants was 38 years (range, 18-58 years) and 42 (70.0%) were women. Geriatric conditions were highly prevalent: severe cognitive impairment was diagnosed in 39 (65.0%) participants, behavioral symptoms were present in 25 (41.7%), and functional impairment in 23 (38.3%). Six (10.0%) participants lived in institutions and 11 (18.3%) were diagnosed as obese. The mean number of drugs used was 2.4; use of psychotropic drugs was highly prevalent. The most common chronic diseases were thyroid problems (44, 73.3%), followed by mood disorders (19, 31.7%), osteoporosis (18, 30.0%), and cardiac problems (10, 16.7%). Geriatric conditions and chronic diseases were more prevalent among participants aged ≥40 years.

CONCLUSION

Several similarities between older adults and adults with DS were observed. Comorbidities, geriatric conditions, cognitive and functional deficits, and social problems are highly prevalent in both populations, contributing to the high complexity of these patients' assessment and treatment.

The bone tissue of children and adolescents with Down syndrome is sensitive to mechanical stress in certain skeletal locations: a 1-year physical training program study

The systemic complications of Down syndrome (DS) attenuate the osteogenic response to physical activity in DS patients. Through an interventional study we showed the effects of physical training on development of bone mineral content (BMC) and density (BMD) as well as on quantitative bone ultrasound (QUS) parameters in individuals with DS. A total of 42 children with DS were randomly assigned to either an exercising (DS-E, n=20, age 16 ± 1.8 years) or non-exercising group (DS-NE, n=22, age 16.9 ± 1.5 years). DS-E group was assigned to a program of osteogenic activities with 60 min sessions twice a week, over 12 month period. Bone mass measures were performed by dual X-ray absorpsiometry (DXA) at the spine and hip, and ultrasound attenuation (BUA) and velocity (SOS) assessed from the calcaneus by QUS device. All bone parameters had evolved with age, except for neck BMD. One year of training increased BMC values at lumbar spine (7%, p<.005) and total hip (10%, p<.05), and BMD values only at lumbar spine (4%, p<.05). Changes in BUA and SOS values were not evident following training. Trained individuals increased their motor skills measured through Eurofit tests. It was concluded that a program of osteogenic physical training may induce bone improvement in children with DS, but with a lower magnitude than that reported in the specialized literature for individuals without DS.

Aneuploidy and skeletal health

The normal human chromosome complement consists of 46 chromosomes comprising 22 morphologically different pairs of autosomes and one pair of sex chromosomes. Variations in either chromosome number and/or structure frequently result in significant mental impairment and/or a variety of other clinical problems, among them, altered bone mass and strength. Chromosomal syndromes associated with specific chromosomal abnormalities are classified as either numerical or structural and may involve more than one chromosome. Aneuploidy refers to the presence of an extra copy of a specific chromosome, or trisomy, as seen in Down's syndrome (trisomy 21), or the absence of a single chromosome, or monosomy, as seen in Turner syndrome (a single X chromosome in females: 45, X). Aneuploidies have diverse phenotypic consequences, ranging from severe mental retardation and developmental abnormalities to increased susceptibility to various neoplasms and premature death. In fact, trisomy 21 is the prototypical aneuploidy in humans, is the most common genetic abnormality associated with longevity, and is one of the most widespread genetic causes of intellectual disability. In this review, the impact of trisomy 21 on the bone mass, architecture, skeletal health, and quality of life of people with Down syndrome will be discussed.

Bone mass and density in preadolescent boys with and without Down syndrome

Preadolescent boys with Down syndrome at 7-10 years of age have lower bone mass and density in the pelvis than age-matched children without Down syndrome. However, bone mass and density of total body less head and lumbar spine are not different between these two groups.

INTRODUCTION

This study aimed to assess bone mineral content (BMC) and density (BMD) in preadolescent boys with and without Down syndrome (DS) at 7-10 years of age.

METHODS

Eleven preadolescent boys with DS and eleven age-matched children without DS participated in this study. Dual-energy X-ray absorptiometry was used to measure BMC and BMD in whole body and lumbar spine. Both BMC and BMD of total body less head (TBLH) and lumbar spine (vertebrae L2-L4) were compared between the two groups, with and without adjusting for physical characteristics such as bone area, body height, and total lean mass. Two bone mineral apparent density (BMAD) variables were calculated to estimate volumetric BMD in the lumbar spine.

RESULTS

Both BMC and BMD in the pelvis were lower in the DS group, after adjusting for physical characteristics. However, with and without adjusting for physical characteristics, the two groups were not different in BMC and BMD of the arms, legs, and TBLH from the whole body scan and in BMC, BMD, and BMAD of the lumbar spine from the lumbar spine scan.

CONCLUSIONS

These findings indicate that the pelvis may be the first site to show the significant difference in BMC and BMD between preadolescent boys with and without DS. It also suggests that significantly lower BMC and BMD in whole body and lumbar spine, which is usually observed in young adults with DS, may not occur before adolescence.

Low bone turnover and low BMD in Down syndrome: effect of intermittent PTH treatment

Trisomy 21 affects virtually every organ system and results in the complex clinical presentation of Down syndrome (DS). Patterns of differences are now being recognized as patients' age and these patterns bring about new opportunities for disease prevention and treatment. Low bone mineral density (BMD) has been reported in many studies of males and females with DS yet the specific effects of trisomy 21 on the skeleton remain poorly defined. Therefore we determined the bone phenotype and measured bone turnover markers in the murine DS model Ts65Dn. Male Ts65Dn DS mice are infertile and display a profound low bone mass phenotype that deteriorates with age. The low bone mass was correlated with significantly decreased osteoblast and osteoclast development, decreased bone biochemical markers, a diminished bone formation rate and reduced mechanical strength. The low bone mass observed in 3 month old Ts65Dn mice was significantly increased after 4 weeks of intermittent PTH treatment. These studies provide novel insight into the cause of the profound bone fragility in DS and identify PTH as a potential anabolic agent in the adult low bone mass DS population.