# A rare variation of ERCC8 gene cause Cockayne syndrome in a Chinese family

## TL;DR

A rare genetic mutation in the ERCC8 gene caused Cockayne syndrome in a Chinese family, enabling better diagnosis and prenatal screening.

## Contribution

Identifies a novel homozygous deletion in ERCC8 as a cause of Cockayne syndrome in a Chinese family.

## Key findings

- Both patients had a homozygous deletion of Exon4 in the ERCC8 gene.
- Prenatal diagnosis confirmed the fetus did not carry the ERCC8 variant.
- The findings aid in accurate genetic counseling and prenatal diagnosis for the family.

## Abstract

Cockayne syndrome (CS) is a multisystem degenerative disorder in which dysplasia and microcephaly represent the primary criteria for diagnosis. we present the cases of two patients who exhibited distinctive facial features and a range of other clinical manifestations, including growth failure, developmental delay, microcephaly, dental anomalies, and unstable gait.

Clinical information pertaining to the patient’s family was collated and the Pedigree chart was drawn. Two milliliters of peripheral blood were drawn from each of the two patients (III1and III3) and their parents, The causative genes were identified by Medical exome sequencing. Furthermore, the pregnant women underwent amniotic fluid prenatal diagnosis at mid-pregnancy (III5).

Medical exome sequencing revealed that both patients had a homozygous deletion of Exon4 in the ERCC8 gene and that both parents were carriers. Prenatal diagnosis by amniotic fluid confirmed that the fetus (III5) did not carry the variant.

This clarified the diagnosis at the genetic level, deepened our understanding of the disease, and facilitated the ability to provide accurate genetic counseling and prenatal diagnosis, with the goal of reducing the number of new affected individuals in the family.