JOURNAL OF BEHCET UZ CHILDRENS HOSPITAL, cilt.15, sa.2, ss.131-135, 2025 (ESCI, TRDizin)
Cystic hygroma (CH) is a lymphatic malformation commonly associated with various genetic disorders, including RASopathies-syndromes caused by mutations in the RAS-MAPK signaling pathway. We present a neonate referred to our center due to CH and dysmorphic facial features. During follow-up, interventricular septal hypertrophy and nystagmus were identified. Molecular analysis revealed a pathogenic c.4A>G (p.Ser2Gly) variant in the SHOC2 gene. This mutation is associated with a rare subtype of RASopathies known as Noonan-like syndrome with loose anagen hair. Although four additional male relatives also exhibited nystagmus, sequencing of the FRMD7 gene and whole-exome analysis did not reveal any other pathogenic variants associated with nystagmus, highlighting the clinical complexity of the case. This report emphasizes the importance of considering the possibility of dual diagnoses in cases presenting with complex clinical features. It also underscores the value of prioritizing multigene panel testing in patients with overlapping phenotypes among RASopathy subgroups, where phenotypic distinctions remain unclear.