medwireNews: Children with Silver-Russell Syndrome (SRS) achieve similar height gains during growth hormone (GH) treatment as other children born small for gestational age (SGA), research shows.

SRS patients did not grow as tall with GH treatment as those born SGA for other reasons, with average final adult height standard deviation scores (SDSs) of –2.17 versus –1.65. But this was because the SRS patients were smaller at baseline, with an average height SDS of –3.67 versus –2.92 in the SGA patients.

In total, the 62 SRS patients gained 1.30 SDS in height, which was similar to the 1.26 SDS gained by the 227 SGA patients, report Carolina Smeets (Erasmus University Medical Centre, Rotterdam, the Netherlands) and co-researchers.

They also note that puberty began significantly earlier in the SRS patients, at an average age of 10.8 years versus 11.7 years in the SGA group, “leading to earlier closure of the growth plates and a lower [adult height] at a younger age.”

The SRS patients began GH treatment earlier, however, at an age average of 4.9 years compared with 6.7 years among SGA patients, giving a significantly longer treatment duration, at 9.6 versus 8.8 years.

Smeets and team found evidence that the underlying cause of SRS may influence treatment response, with the 11 patients with maternal uniparental disomy of chromosome 7 (mUPD7) and the 20 with idiopathic SRS tending to do better than the 31 patients with alterations in the 11p15 region.

The three groups had similar baseline height SDSs and were treated for equivalent durations, but the height SDS gains were 1.37 and 2.04 in the idiopathic and mUPD7 groups, respectively, compared with 0.91 in the 11p15 group.

Although not statistically different, the trend “is in line with a previous study reporting that the 11p15 alterations cause a more severe phenotype of SRS”, write the researchers in The Journal of Clinical Endocrinology & Metabolism.

But they add: “As those with an 11p15 alteration also increase their height with almost 1 SDS, we consider GH treatment also beneficial for SRS patients with an 11p15 alteration.”

Patients in the 11p15 subgroup had a notably increased insulin-like growth factor-1 (IGF-1) SDS after 1 year of GH treatment, at 2.10 compared with between 0.65 and 0.92 in the other subgroups, which the researchers say is in line with the reported reduced IGF-1 sensitivity in SRS patients with 11p15 alterations.

However, they found that levels near the end of treatment were similar across the subgroups and not significantly different to that in the SGA group, which they describe as “reassuring”.

By Eleanor McDermid

J Clin Endocrinol Metab 2016; Advance online publication

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