medwireNews: Young children with short stature due to aggrecan (ACAN) deficiency achieve a marked improvement in height velocity during their first year of treatment with recombinant human growth hormone (rhGH), shows a cohort study.
“It will be interesting to see if patients allowed to progress through puberty normally will have a strong pubertal growth spurt and experience a lasting positive impact on adult height outcome”, the researchers write in The Journal of Clinical Endocrinology & Metabolism.
The 10 children all had confirmed heterozygous mutations in ACAN and their median height standard deviation score (SDS) at the start of treatment was –2.5, ranging from –4.3 to –1.1.
The target daily dose of rhGH was 50 µg/kg, but the average dose being used after 1 year of treatment was 41 µg/kg, after five patients had a dose reduction because of elevated insulin-like growth factor-1 levels.
Nevertheless, the children achieved a significant increase in height velocity, from a median of 5.2 cm/year (range 3.8 to 7.1 cm/year) before treatment to 8.3 cm/year (range 7.3 to 11.2 cm/year) during the first year of rhGH therapy. This resulted in a median improvement in height SDS of 0.62.
“It was reassuring that the [bone age] advancement, often observed in aggrecan deficient patients, did not worsen while on rhGH therapy”, say Philippe Backeljauw (Cincinnati Children’s Hospital Medical Center, Ohio, USA) and co-researchers.
At baseline, the children’s median chronological age was 5.6 years, whereas their bone age was 6.9 years, giving a median ratio of 1.2. During the first year of rhGH treatment the ratio increased by a nonsignificant 0.10.
Just one patient had a significant increase in bone age during treatment, but this occurred “in the context of excessive weight gain in an already obese individual”, say the researchers.
They say that the study participants have been enrolled into an extension trial, to ascertain the longer-term effects of rhGH on height velocity.
“It should be noted that an increase in [height velocity] was observed on a lower-than-intended rhGH dosing”, say Backeljauw and team.
“The ability to achieve good catch-up growth, and continued normal growth afterwards on lower doses of GH will be desirable in aggrecan deficient patients, given their underlying propensity to present with [bone age] advancement.”
By Eleanor McDermid
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