Dysgenesis of the posterior segment of the corpus callosum: don’t miss SPG45!

Disgenesia do segmento posterior do corpo caloso: lembre-se da SPG45!

In hereditary spastic paraplegias (HSPs), magnetic resonance imaging (MRI) scans of the brain typically show the involvement of the anterior part of the corpus callosum with abnormalities in the white matter fibers of the forceps minor(“ears of the lynx sign”). However, these imaging findings are particularly associated with spastic paraplegia type 11 (SPG11) or spastic paraplegia type 15 (SPG15).¹

A child with spastic gait achieved independent walking at the age of 2 years, and 3 years later was referred to our service for investigation. A brain MRI demonstrated corpus callosum dysgenesis and peritrigonal white matter abnormality (►Figure 1). Whole exome sequencing revealed compound heterozygosity for two novel likely pathogenic variants in NT5C2 (p.[Leu468Pro] and p.[Gln542Argfs*71]), consistent with SPG45, of the SPG subtypes with thin corpus callosum.²

Figure 1
Brain MRI. (A) Sagittal T1 postcontrast shows hypoplastic corpus callosum with marked reduction of the splenium and posterior segment of its body (arrows), characteristic, even though not specific, of this disease. (B) Axial fluid-attenuated inversion recovery (FLAIR) demonstrates symmetric and bilateral peritrigonal white matter changes (arrowheads). The ears of the lynx sign is not usually observed in these cases.

References

• ¹
  Pascual B, de Bot ST, Daniels MR, et al. “Ears of the Lynx” MRI Sign Is Associated with SPG11 and SPG15 Hereditary Spastic Paraplegia. AJNR Am J Neuroradiol 2019;40(01):199–203
• ²
  Elsaid MF, Ibrahim K, Chalhoub N, Elsotouhy A, El Mudehki N, Abdel Aleem A. NT5C2 novel splicing variant expands the phenotypic spectrum of Spastic Paraplegia (SPG45): case report of a new member of thin corpus callosum SPG-Subgroup. BMC Med Genet 2017;18(01):33

Publication Dates

• Publication in this collection
  19 May 2023
• Date of issue
  Mar 2023

History

• Received
  19 Aug 2022
• Reviewed
  13 Oct 2022
• Accepted
  21 Oct 2022