News in brief: Vitamin D and BMD boost in Tas; Height gain with vosoritide in kids; Genetic clue to shared aetiology in T1D and T2D

Vitamin D turn around improves bone health

Altered sun exposure behaviours and vitamin D supplement use have been positively associated with increases in serum 25-hydroxyvitamin D concentration over ten years, according to evidence from the Tasmanian Older Adult Cohort study.

The study compared 25(OH)D levels in more than 1,000 Australians 50-80 years old at baseline in 2002-2004. Data from 565 participants was available at the 10-year follow-up.

It found deseasonalised 25(OH)D increased over the study period as did the percentage of participants attaining levels ≥50 nmol/L and therefore considered vitamin D sufficient.

“Compared to participants who were always vitamin D deficient, persistent vitamin D sufficiency was associated with significantly less BMD loss at the femoral neck, total hip and lumbar spine and achieving vitamin D sufficiency was associated with significantly less BMD loss at the lumbar spine,” the study said.

The study noted that vitamin D supplement use by participants increased 16-fold, mirroring that in the community.

“Our data therefore most likely capture the influence of universal 25(OH)D measurement superimposed on existing trends in clinical practice and public health messages, resulting in an accentuated improvement in cohort vitamin D status.”

The Journal of Clinical Endocrinology and Metabolism

Growth spurt achieved in children with achondoplasia

Australian-led research has shown vosoritide has persistent two-year beneficial effects on growth in children with achondroplasia.

Professor Ravi Savarirayan, group leader in skeletal therapies at the Murdoch Children’s Research Institute, presented the findings recently at ENDO 2021. The findings extend earlier results published in The Lancet last year.

Mean annualised growth velocity (AGV) was 4.28 cm/year at baseline, 5.71 cm/year after one year of daily treatment with vosoritide and 5.65 cm/year after the second year of treatment with the C-type natriuretic peptide analogue.

The children also had a better height z-score after the second year of treatment and showed a trend towards a better ratio of upper to lower body segments.

Longer term follow-up is ongoing where additional data on quality of life, functional measures and final adult height will help to confirm the clinical relevance of these improvements in growth and proportionality.

Overlapping genetic association in T1D and T2D

Five genetic variants in different chromosome regions impact the risk of developing both type 1 and type 2 diabetes.

The data from GWAS meta-analyses in both conditions in European populations found four signals (near CTRB1/BCAR1, INS, TMEM129 and PGM1) co-localised between the two diseases.

In all four cases, the allele increasing risk for one disease was protective against the other.

A fifth association, near GLIS3, is likely to co-localise between diseases, with concordant direction of effect.

“That four of five co-localisation signals had opposite directions of effect implies a complex genetic relationship between the two diseases,” the study said.

“While the directional discordance offers little hope for effective treatments for both diseases simultaneously at these particular targets, it can offer biological insight into the disease pathways that these regions act upon, and even if there is directional discordance, the genetics could be highlighting the same therapeutic target.”



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