Variable expressivity of Malan syndrome

Area of Science:

• Genetics
• Neurodevelopmental Disorders
• Clinical Medicine

Background:

• Malan syndrome is a rare genetic disorder characterized by developmental delay, intellectual disability, and distinctive facial features.
• The NFIX gene plays a crucial role in brain development, and mutations in NFIX have been linked to various neurodevelopmental conditions.

Observation:

• A family presented with a child exhibiting developmental delay, macrocephaly, dysmorphic facial features, and autism.
• The child's mother shared macrocephaly and similar facial features but lacked the neurodevelopmental issues observed in her son.

Findings:

• Genetic analysis revealed a heterozygous frameshift variant (NFIX: c.34_41dupGGGATACC) in both the child and his mother.
• The clinical presentation in the child and mother was consistent with Malan syndrome, despite differing neurobehavioral phenotypes.

Implications:

• This case underscores the significant variable expressivity of Malan syndrome, even within the same family.
• Understanding NFIX variant expressivity is crucial for accurate genetic diagnosis and counseling in families with developmental disorders.
• Further research into genotype-phenotype correlations in Malan syndrome is warranted to elucidate the mechanisms underlying variable expressivity.