First Report of Concomitant Pathogenic Mutations Within MGC4607/CCM2 and KRIT1/CCM1 in a Familial Cerebral Cavernous Malformation Patient

Abstract

Background: Familial cerebral cavernous malformations (CCM) are among the most common vascular malformations of the central nervous system (CNS) and are linked to mutations on the specific genes CCM1/KRIT1, CCM2/MGC4607, and CCM3/PDCD10. We present the first report in the literature of a pharmaco-resistant epileptic patient harboring co-occurring pathogenic mutations within CCM2/MGC4607 and CCM1/KRIT1.

Case description: A 51-year-old patient first presented at age of 33 years with episodes of seizures. Magnetic resonance imaging including a susceptibility-weighted imaging sequence had shown multiple cerebral cavernous malformation lesions. She had partial response of symptoms and remained in routine follow-up needing progressive pharmacological improvement. Direct sequencing allowed the detection of 1 nonsense pathogenic mutation in CCM2/MGC4607 (c.118C>T; p.Arg40Ter) and 1 unclassified frameshift insertion variant in CCM1/KRIT1 (c.1687_1688insT; p.Tyr563LeufsTer5).

Conclusions: Although the CCM2/MGC460 variant seems to be the major contributor for the patient's CCM phenotype, the mutated CCM1/KRIT1 seems to act as a booster to CCM overall pathogenicity.

Keywords: CCM1 (KRIT1); CCM2 (MGC4607); Cerebral cavernous malformation; Epilepsy.