A case report on moyamoya syndrome associated with Noonan-like syndrome with loose anagen hair and growth hormone insufficiency

Introduction: Noonan-like syndrome with loose anagen hair (NS/LAH) is a RASopathy caused by genetic variants in SHOC2. There are now several reports of moyamoya syndrome in association with this condition and with Noonan and other Noonan-like syndromes. Case Presentation: We report the case of a young boy with NS/LAH secondary to the c.4A>G, p.Ser2Gly variant in SHOC2 who was subsequently diagnosed with growth hormone insufficiency. Although the pituitary appeared normal on brain magnetic resonance imaging, findings consistent with moyamoya syndrome were identified and subsequently confirmed by magnetic resonance angiography. He remains on growth hormone treatment, with ongoing close surveillance planned to monitor the progression of his moyamoya. Growth hormone insufficiency predominates as the cause of short stature in NS/LAH. We conducted a comprehensive review of published case reports to date on patients with Noonan and Noonan-like syndromes and moyamoya syndrome. From this review, we identified 13 clinically diagnosed cases. Genotype data was only available for 5 patients, 3 of whom had NS/LAH secondary to SHOC2 variants. To our knowledge, our patient represents the 4th reported case with NS/LAH and moyamoya. Conclusion: The possibility of moyamoya should be considered during follow-up of patients with Noonan and Noonan-like syndromes, including NS/LAH, to facilitate timely recognition and intervention.