Endocrine Abstracts

JOINT3544

Introduction: Noonan syndrome (NS) is a rare autosomal dominant disorder caused by mutations in genes involved in the RAS-MAPK signaling pathway, most commonly the PTPN11 gene. Patients with this syndrome exhibit characteristic dysmorphic features, cardiac anomalies, and growth delay. Among these manifestations, growth delay is one of the most common signs. Treatment with recombinant growth hormone (rhGH) is a widely used approach to stimulate growth in these patients.

Clinical Observation: We report the case of a 13-year-old boy, born by vaginal delivery with a birth weight of 1,800 g. He presents with characteristic dysmorphic features of Noonan syndrome, including low-set hairline and ears, hypertelorism, a triangular face, a mildly deformed chest, and widely spaced nipples. He measures 140.5 cm (< -3 SD) and weighs 29 kg (< -3 SD), indicating severe growth retardation. His genital examination revealed a penile length of 4.5 cm and testes measuring 2 × 1.5 cm. Biological investigations revealed an IGF-1 level of 169.2 ng/ml with a Z-score of -0.74. Bone age assessment showed a delay of 1 year and 2 months (bone age of 12 years). Additional investigations, including hypothalamic-pituitary MRI, renal ultrasound, and echocardiography, were normal. Furthermore, an insulin-induced hypoglycemia test showed no growth hormone deficiency. Treatment with recombinant growth hormone (rhGH) was initiated to stimulate growth. Regular follow-up is planned to evaluate the treatment response and monitor potential complications, particularly cardiac ones.

Discussion: Growth delay affects 50 to 70% of children with Noonan syndrome and often becomes apparent between the ages of 3 and 4 years. During childhood, these children generally have a height below the age-related norms. In adolescence, growth delay may worsen due to frequent pubertal delay in both sexes. Multiple factors can contribute to this growth delay, including growth hormone deficiency or IGF-1 resistance. In this context, treatment with recombinant growth hormone (rhGH) is a commonly used strategy to enhance growth. The results are generally positive, with notable improvements in growth velocity. However, cardiac abnormalities and the increased risk of hematological disorders often associated with Noonan syndrome require regular and thorough medical monitoring.

Conclusion: Growth delay in Noonan syndrome requires early and tailored management, along with regular follow-up, to improve growth and enhance the quality of life of patients.