Genetic counselling and testing for inherited dementia: single-centre evaluation of the consensus Italian DIAfN protocol

Abstract

Background A consensus protocol for genetic counselling and testing of familial dementia, the Italian Dominantly Inherited Alzheimer’s and Frontotemporal Network (IT-DIAfN) protocol, has been developed in Italy by a network of expert dementia centres. The aim of this study is to evaluate feasibility and acceptability of the genetic counselling and testing process, as undertaken according to the IT-DIAfN protocol in one of the IT-DIAfN dementia research centres. Methods The protocol was tested by a multidisciplinary team at the IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy, on affected individuals with suspected inherited forms of Alzheimer’s disease (AD) or frontotemporal dementia (FTD), and to healthy at-risk relatives. The genetic counselling and testing process consisted of (i) pre-test consultation and psychological assessment (ii) genetic testing, (iii) genetic test result disclosure and (iv) follow-up consultation and psychological assessment. Results Twenty affected individuals from 17 families fulfilled the family history criteria of the IT-DIAfN protocol for suspected inherited dementia (17 for AD, 2 for FTD, 1 for inclusion body myopathy with Paget disease of bone and frontotemporal dementia) and were included in the protocol. Nineteen out of 20 affected individuals received the genetic test result (one left after the pre-test consultation being not ready to cope with an unfavourable outcome). A pathogenic mutation was found in 6 affected individuals (1 in PSEN1, 2 in PSEN2, 1 in GRN, 1 in MAPT, 1 in VCP). Eleven healthy at-risk relatives asked to undergo predictive testing and were included in the protocol. Three completed the protocol, including follow-up; one did not ask for the genetic test result after genetic testing; and eight withdrew before the genetic testing, mainly due to an increased awareness about the possible consequences of an unfavourable test result. To date, no catastrophic reactions were reported at the follow-up. Conclusions Our case series shows that a structured genetic counselling and testing protocol for inherited dementia can be implemented in both affected individuals and at-risk relatives in a research setting. The procedure was shown to be safe in terms of occurrence of catastrophic events. A formal validation in larger cohorts is needed.

Psychological Impact of Predictive Genetic Testing for Inherited Alzheimer Disease and Frontotemporal Dementia

“…Families with inherited dementia had been selected from a clinical series of consecutive patients admitted to two IT-DIAfN centers (IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy, in collaboration with Briolini Hospital of Gazzaniga, Bergamo, Italy, and IRCCS Fondazione Istituto Neurologico Carlo Besta, Milan, Italy). The results from the series of affected individuals were previously reported 13…”

“…The results from the series of affected individuals were previously reported. 13 We included thirteen families (6 AD and 7 FTD) with a known pathogenic mutation, namely: 3 in PSEN1 (M233T, G184G, L392V); 2 in PSEN2 (M239I); 1 in MAPT (P301L); 7 in GRN (6 T272fs, 1 C157fs). We estimated from pedigrees that 56 first-degree relatives at 50% risk were potentially eligible for the IT-DIAfN protocol.…”

“…The IT-DIAfN protocol was described in detail elsewhere 12,13. Briefly, the counseling protocol for healthy at-risk relatives consisted of: (i) at least 2 pretest consultations, including the psychological assessment; (ii) blood sampling; (iii) disclosure of the genetic test result; (iv) follow-up.…”

“…A multidisciplinary team of health professionals – a geneticist, a neurologist or geriatrician with a consolidated background in neurodegenerative disease, and a psychologist or psychiatrist with expertise in counseling – provided care at all stages of the protocol in order to facilitate fully informed and autonomous decision making 7. The IT-DIAfN protocol was implemented within a research framework in centers participating in the IT-DIAfN network, showing that the procedure was feasible and safe in terms of occurrence of catastrophic events 13…”

“…7 The IT-DIAfN protocol was implemented within a research framework in centers participating in the IT-DIAfN network, showing that the procedure was feasible and safe in terms of occurrence of catastrophic events. 13 The aim of this study is to investigate the psychological impact of predictive genetic testing in healthy at-risk relatives, based on data collected with a comprehensive psychological assessment.…”