Systematised naevus sebaceus resulting from post-zygotic mutation in HRAS

Area of Science:

• Genetics
• Dermatology
• Molecular Biology

Background:

• Naevus sebaceus is a congenital skin disorder.
• Recent research links it to post-zygotic mutations in RAS genes (HRAS, KRAS, NRAS).

Observation:

• A neonate presented with extensive naevus sebaceus.
• Genetic analysis was performed on lesional skin DNA.

Findings:

• A pathogenic HRAS mutation (c.37G>C; p.Gly13Arg) was identified in the lesional skin DNA.
• The mutation was mosaic, confirming a RASopathy diagnosis.

Implications:

• This case underscores the clinicopathological and molecular features of naevus sebaceus.
• It highlights the importance of genetic assessment and management strategies for mosaic RASopathies.