Cockayne syndrome (CS) is a rare, multisystemic, neurodegenerative disease with clinical signs of growth and developmental delay, microcephaly, sensorineural hearing loss, cataract/retinopathy, dental anomalies and sensitivity to sunlight. CS has been due to damaged `nucleotide excision repair` and defects in mitochondrial functions together. Mutations in the ERCC6 and ERCC8 genes cause CS. CS is a clinical spectrum. The mild end of this spectrum is UV-sensitive syndrome, while the most severe end is prenatal type. Classic form, late-onset and adult-onset form, xeroderma pigmentosum- Cockayne syndrome constitute intermediate forms. Clinical diagnosis in CS patients can be confirmed by molecular methods such as microarray and whole exome sequencing. In this presented case, after a normal pregnancy, the patient had hearing loss, cataract, microcephaly, growth and developmental retardation and malnutrition in the first months. Homozygous splice site mutation was found in ERCC6 gene. As the findings did not start during pregnancy, classical type features and prenatal type features together with rapid onset in early life were found together and suggested that there are no sharp boundaries between subgroups.

Keywords: Cockayne syndrome, whole exome sequencing, ERCC6 gene