Introduction:
Familial forms of cerebral cavernous malformations (CCM) account for about 1/3 of cases, involving autosomal dominant inheritance at 1 of 3 gene loci. Few studies have examined any special features of the rarest cases with
CCM3 (PDCD10
) mutation at q3, constituting <15 % of probands genotyped by sequential mutation screening, and <2% of CCM cases at large.
Hypothesis:
We hypothesize that CCM3 cases have unique phenotypic features not recognized in the more common CCM1 and 2 families, or in sporadic cases.
Methods:
Twelve probands including 17 subjects with confirmed
CCM3
mutations were prospectively enrolled through systematic facilitated referral by the patient advocacy group Angioma Alliance. Clinical features were catalogued, including high sensitivity susceptibility weighted imaging (SWI). Rates of overt hemorrhage were determined based on adjudicated criteria. Comparisons were made to systematic literature review of natural history data on non-CCM3 cases.
Results:
The first overt hemorrhage occurred most often in the 1st decade of life (mean age 5.8). Nine of 17 subjects (52%) suffered 30 overt hemorrhages, with an estimated incidence of 6.7 % /patient/year based on exposure risk since birth, and 17% /patient/year based on risk since first symptom onset. Lesion burden on SWI was exceptionally high, >100 lesions in 28%, and > 20 lesions in 72% of cases, respectively. Adjusted bleed rate was <0.5% /lesion/year. New SWI lesions formed at a rate of 2.7/patient/year in prospective follow-up, and 1.8/patient/year based on years since birth. Scoliosis was found in 47% (an association not recognized previously), skin lesions in 29.4%, and brain tumors in 29.4% of cases, respectively. Cognitive disability affected 47% of cases, mostly in association with high lesion burden. Six of 15 cases with parental screening (40%) represented a spontaneous mutation.
Conclusion:
CCM3 is exceptionally aggressive compared to other familial and sporadic CCM. High risks of bleeding and cognitive disability mostly reflect severe lesion burden early in life, rather than a higher risk per lesion. These results will inform the design of clinical trials, urgently needed to address this unique CCM cohort.
Molecular genetics of familial cerebral cavernous malformations