Classic Rett syndrome in a boy with R133C mutation of MECP2

Area of Science:

• Genetics
• Neurology
• Developmental Biology

Background:

• Rett syndrome (RTT) is a rare genetic neurodevelopmental disorder primarily affecting females.
• Mutations in the methyl-CpG-binding protein 2 (MECP2) gene are the main cause of RTT.
• While most males with MECP2 mutations experience severe outcomes, the presentation of RTT in males is debated.

Observation:

• This report describes a boy diagnosed with classic RTT.
• The patient presented with motor delays and stereotypic hand movements, progressing to severe disability.
• Genetic analysis revealed a missense mutation (R133C) in the MECP2 gene, inherited from his mother who was a carrier with mild symptoms.

Findings:

• The R133C mutation in MECP2 was identified in the affected male and his sister, who also had classic RTT.
• This specific mutation was previously identified in females with RTT but not in males with non-specific X-linked mental retardation.
• The study suggests that the location of the MECP2 mutation, specifically at residue 133, is critical for inducing RTT phenotypes in humans, irrespective of sex.

Implications:

• This case challenges the notion that MECP2 mutations are exclusively associated with severe outcomes in males.
• It highlights the importance of mutation position within the MECP2 gene in determining clinical presentation and severity.
• Understanding mutation-specific effects can refine diagnostic approaches and inform potential therapeutic strategies for RTT.