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

Abstract

To explore the genotypic and phenotypic characteristics of a child with congenital Pelizaeus-Merzbacher disease. Clinical, imaging and genetic characteristics of the child were retrospectively analyzed. 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. 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.