Noonan syndrome: rhGH treatment and PTPN11 mutation

Objective: To analyze the clinical data and genetic characteristics of Noonan syndrome, both the effect and side effects of recombinant human growth hormone (rhGH) treatment.

Methods: We collected clinical data from 8 children with Noonan syndrome diagnosed from November 2017 to June 2021. The diagnosis was clarified by exome second-generation sequencing and parental PCR-NGS validation and interpretation of the preceding evidence, and growth hormone therapy was administered. Of the cases, four males and four females were seen for slow height growth and the median age at diagnosis was 8 years 7 months (1 year 7 months to 12 years 6 months).

Results: Here, 7 children were treated with rhGH. Compared to the pre-treatment period, the growth rate increased after rhGH treatment [3.7 ± 0.5 cm/year before treatment and 8.0 ± 1.0 cm/year after treatment, p < 0.01], with the maximum growth rate between 3 and 6 months of treatment and decreasing with the duration of treatment thereafter. The growth hormone treatment was discontinued and the orthopedic consultation was ordered with regular follow-up, which was considered to be related to the PTPN11 mutation.

Conclusion: Noonan syndrome is characterized by slow growth, short stature, mental retardation, peculiar facial features, structural heart abnormalities and abnormal bone metabolism. and osteochondroma was found after case 2 rhGH treatment. Genetic examination is mostly caused by PTPN11 mutation. It is recommended to pay attention to bone metabolism abnormalities before growth hormone treatment, especially in children with PTPN11 mutations.