Further genotype-phenotype correlation emerging from two families with PLP1 exon 4 skipping

Roberta Biancheri, Serena Grossi, Stefano Regis, Andrea Rossi, Fabio Corsolini, Daniela Paola Rossi, Pietro Cavalli, Mariasavina Severino, Mirella Filocamo

Research output: Contribution to journalArticlepeer-review


Proteolipid protein 1 (PLP1) gene-related disorders due to mutations in the PLP1 include a wide spectrum of X-linked disorders ranging from severe connatal Pelizaeus-Merzbacher disease (PMD) to spastic paraplegia 2 (SPG2). Duplications, deletions or point mutations in coding and noncoding regions of the PLP1 gene may occur. We report the clinical, neuroradiologic and molecular findings in six patients from two unrelated families. The affected males showed severe mental retardation, spastic tetraparesis, inability of walking and pes cavus at onset in early infancy. Brain magnetic resonance imaging (MRI) showed hypomyelination and brain atrophy. Nystagmus was never observed. The affected females showed adult-onset progressive spastic paraparesis leading to wheel-chair dependency and subtle white matter changes on brain MRI. Molecular studies in the two families identified two different intronic mutations, the novel c.622+2T>C and the known c.622+1G>A, leading to the skipping of PLP1-exon 4. The clinical presentation of the affected males did not consistently fit in any of the PLP1-related disorder subtypes (i.e., connatal or classic PMD, SPG2 and 'PLP1 null syndrome'), and in addition, the carrier females were symptomatic despite the severe clinical picture of their respective probands. This study provides new insight into the genotype-phenotype correlations of patients with PLP1 splice-site mutations.

Original languageEnglish
Pages (from-to)267-272
Number of pages6
JournalClinical Genetics
Issue number3
Publication statusPublished - Mar 2014


  • Magnetic resonance imaging
  • Molecular genetics
  • Pelizaeus-Merzbacher disease

ASJC Scopus subject areas

  • Genetics(clinical)
  • Genetics


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