Phenotypic and Molecular Features of a Large ODDD Family: Expanding the Spectrum of CX43-Related Disorder

We present a family of five siblings who came to our attention with a clinical and radiological diagnosis of familial hypomyelinating leukodystrophy. Despite brain white matter abnormalities being present in all siblings, the clinical phenotype was variable: the three brothers presented with a clear-cut late-onset spastic paraplegia, whereas the two sisters displayed only mild pyramidal signs. Molecular analysis revealed a single relevant variant shared by all affected siblings, namely the likely pathogenic variant c.659C>T (p.Ser220Phe) in the GJA1 gene. Variants in this gene are generally associated with oculodentodigital dysplasia (ODDD), an autosomal dominant condition characterized by distinctive facial features and anomalies of the eyes, teeth, and digits. Neurological features are reported in about 30% of cases. In this family, ODDD manifested as a predominantly neurological phenotype. Although a clear explanation for this uncommon presentation is lacking, shared genetic modifiers, the effect of the specific variant, and a possible patient-population bias may have contributed. This case highlights the wide phenotypic spectrum of CX43-related disorders and suggests the importance of testing the GJA1 gene in individuals with atypical presentations, including predominant or isolated neurological phenotypes such as late-onset spastic paraplegia. MRI findings may also provide a useful diagnostic clue when ODDD is suspected.