[Analysis of genomic copy number variants in a patient with congenital type Pelizaeus-Merzbacher disease].

Objective: To explore the genotypic and phenotypic characteristics of a child with congenital Pelizaeus-Merzbacher disease.
Methods: Clinical, imaging and genetic characteristics of the child were retrospectively analyzed.
Results: The patient manifested significantly reduced muscle tension, apparent tremor of eyeballs, and retardation of motor development after birth. Cranial MRI at 6-month-old showed no myelinization of brain white matter, though no pathogenic variant was detected by clinical exome sequencing. A copy number variation was found at chrX: 102 192 246-103 045 526. The duplication has spanned approximately 853 kb and was recorded in the Decipher database to be associated with Pelizaeus-Merzbacher disease. Quantitative PCR confirmed that the duplication has derived from his mother.
Conclusion: Reduced muscle tension, nystagmus, poor motor development, and absence of myelinization of white matter should alert the diagnosis of congenital type Pelizaeus-Merzbacher disease. Both sequence variant and copy number variation should be searched upon genetic testing. A clear diagnosis is required for genetic counseling.