Pelizaeus-Merzbacher disease (PMD)
https://www.nature.com/articles/s41439-024-00306-8
Pelizaeus-Merzbacher disease (PMD) is a rare genetic disorder and a form of X-linked leukodystrophy that affects the nervous system, leading to problems with movement, muscle control, and vision. It is caused by mutations in the PLP1 gene, which plays a role in producing myelin, a substance that helps nerve cells communicate. PMD has different levels of severity, ranging from mild muscle stiffness to severe developmental delays and inability to walk. This report describes a 29-year-old man from Brazil with classic PMD. His symptoms began in infancy with weak muscle tone, involuntary eye movements, and difficulty coordinating movement. As he grew older, he developed spastic paraparesis (stiffness and weakness in the legs), optic atrophy (vision loss due to nerve damage), trouble swallowing, and worsening head tremors. He also experienced intellectual disability, behavioural changes (such as aggression and mood swings), and appendicular ataxia (loss of coordination in the limbs). Brain scans showed abnormal white matter and loss of brain tissue in key areas, confirming a hypomyelination disorder. Genetic testing confirmed the Ala21Val mutation in the first transmembrane domain of PLP1, a region crucial for myelin function. The mutation was inherited from his mother, who showed mild tremors but no major neurological impairments. Although similar mutations in this region of PLP1 have been linked to PMD, this specific variant had not been well-documented. Advanced genetic analysis tools predicted this mutation to be highly damaging, further supporting its role in causing PMD. This case expands our understanding of PMD and highlights the importance of genetic testing in diagnosing rare diseases. Identifying more cases like this can improve patient care and provide insights into how different PLP1 mutations affect disease severity.