Presymptomatic genetic testing in CADASIL

Genetic counselling has been poorly investigated in cerebrovascular diseases. Characteristics, motivations and long-term outcome of presymptomatic tests (PT) in subjects at risk of CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) were investigated at the National Centre for Rare Vascular Diseases of the Brain and/or Retina (CERVCO). Sociodemographic, motivational and psychological variables were collected between 2003 and 2010 for PT applicants. Multidisciplinary consultations (with a geneticist, neurologist and psychologist) were proposed over a 6 month period. When PT showed a deleterious mutation of the NOTCH3 gene, cognitive performances, mood, autonomy and quality of life were also assessed. Over 7 years, only 33 subjects asked for a PT of CADASIL. They were predominantly women, lived as a couple, had children and were of high sociocultural level. The dropout rate after the first step of the procedure was 63%. The characteristics of the 11 subjects who reached the end of the procedure did not differ from the 22 who dropped out. Six were carriers of the deleterious mutation and were still asymptomatic after a mean follow-up of 19 months. They did not experience any particular negative event and all of them indicated a high score of overall quality of life. Indeed, two carriers gave birth to their first child. These initial data in CADASIL show that PT is rarely requested and that there is a high dropout rate. Our study also highlights that a multidisciplinary and multistep procedure in genetic counselling testing appears useful to obtain minimal harmful consequences of genetic testing.