# KRAS G12D mosaic mutation in a Chinese linear nevus sebaceous syndrome infant

## TL;DR

A 3-month-old infant with a skin condition and seizures was found to have a rare KRAS gene mutation, which may explain her symptoms and guide treatment.

## Contribution

This is the first reported case of a KRAS G12D mosaic mutation in a patient with linear nevus sebaceous syndrome.

## Key findings

- A low-level KRAS G12D mutation was detected in a patient with linear nevus sebaceous syndrome.
- The mutation is hypothesized to be linked to the patient's skin lesions, eye abnormalities, and epilepsy.
- Accurate diagnosis enabled targeted treatment for the infant.

## Abstract

Linear nevus sebaceous syndrome (LNSS) is a multisystem disorder that includes nevus sebaceous and central nervous system, ocular and skeletal anomalies. We report the first case of a KRAS G12D mosaic mutation in a patient diagnosed with LNSS.

A 3-month-old female with a clinical diagnosis of LNSS presented with intermittent epilepsy. Her mother carefully collected a skin lesion sample from scratched-off scurf obtained from the patient’s nails. DNA was extracted, and long-range PCR was performed to amplify the KRAS gene, which was then analyzed by next-generation sequencing. The results revealed the presence of a low-level heterozygous mutation in the KRAS gene (c.35C>T; p.G12D, 5 %).

These findings suggest that the KRAS somatic mosaic mutation in this patient may have caused her skin and eye lesions and epilepsy. With this correct diagnosis, the infant can be effectively treated.