Fragile X Syndrome (FXS) and Williams-Beuren Syndrome (WBS) are relatively rare disorders characterized by developmental delay associated to socio-communicative deficit and autistic-like behaviours. FXS is one of the most common monogenetic cause of syndromic Autism Spectrum Disorder (ASD); up to 60% of males with FXS meet criteria for ASD. Furthermore, around 30%- 35% of children with WBS meet criteria for ASD. WBS has been considered for a long time as the "polar opposite" of ASD, given their hypersociable phenotype and their abnormal interest in social engagement. Nonetheless, recent researches have emphasized similarities between ASD and WBS phenotypes. By following Vivanti "social abnormalities in ASD and WS can be characterized in terms of analogous difficulties in social cognition (the ability to read others' behaviour), and distinct patterns of social motivation (the propensity for social approach/engagement) which appears to be reduced in ASD and enhanced in WS". More than opposite condition, VIvanti suggests that WBS and ASD could share the same difficult in comprehension of social relationship, with opposite pattern of social engagement (enhanced in WBS and weakened ASD). Moreover, some researches showed that children with WS were similarly delayed in global adaptive functioning when compared to ones with ASD. Given, these similarities authors suggest to test the feasibility and validity of therapy for ASD in children with WBS. Parent Mediated Therapy (PMT) is a group of "technique-focused interventions where the parent is the agent of change and the child is the direct beneficiary of treatment". Italian Guidelines for ASD highlight the importance of PMT for ASD treatment. PMT is also strongly recommended by NICE Clinical Guideline CG170 and WHO Mental Health Gap Action Program. PMT has showed evidence of effectiveness in short and long-term symptom reduction in young children with ASD. A research project on the effectiveness of PMT for children with ASD has been activated since 10 years at the Bambino Gesù Children Hospital (BGCH) in Rome. In last years, a semi-manualized intervention called "Cooperative Parent Mediated Therapy" (CPMT) has been systematized. Following Bearss' Parent Training taxonomy, CPMT is a targeted parent-mediated intervention focused on the ASD core symptoms. CPMT is based on the most significant models of parent training for ASD, in the perspective of Naturalistic Developmental Behavioral Interventions-NDBI with specific attention to the promotion of cooperative interactions. The aim of CPMT is to improve parental skills, to enable parents promoting the following seven target skills in their child: socio-emotional engagement, emotional regulation, imitation, communication, joint attention, play and cognitive flexibility and cooperative interaction. An individualized treatment plan is designed for each child in order to determine his developmental level and treatment goals. CMPT usually last 6 months, for a total amount of 15 sessions of 90 min; twelve core sessions (one session per week) are delivered in the first 3 months, followed by 3 monthly booster sessions. Each weekly core session had a specific focus and specific intervention strategies based on active parent coaching during parent-child interaction, and included the parent-child dyad with the parent being actively coached by a trained therapist. Live active coaching increases parents' competence in implementing strategies to enhance child development, and at the same time increases their confidence. This intervention has demonstrated evidence of effectiveness in socio-communicational improvement as measured by ADOS-G in a randomized controlled trial (RCT). On this purpose, some recent researchers have extended the use of PMT to children with genetic disorders and autistic features, such as Fragile X Syndrome (Vismara et al., 2019). While showing encouraging results, the samples of research were limited (four participants); moreover, parent coaching took place mainly through digital services (e.g. video call). Authors suggest implementing RCTs with larger samples in order to evaluate validity of PMT for individuals with FXS. Moreover, as far as we know, there are currently no researches of PMT in patients with WBS.

Since 2017, an experimental, non-pharmacological, randomized, controlled monocentric and non-profit study was started at BGCH in order to verify effectiveness of CPMT for socio-communicative deficit in children with FXS and WBS. Our hypothesis is that CPMT, in addition to conventional rehabilitation therapies (mainly speech therapy and occupational therapies), could contribute to the enhancement of socio-communicative skills and the reduction of behavioural problems. We also expected also an improvement in family quality of life and a reduction of parental stress. The intervention is provided by psychologists with specific training and expertise in CPMT and monitored through supervision by a senior child psychiatrist

Assessment: Children and their family will be evaluated at two time-points, pre randomization (T0) and six months later, at the end of control/treatment period (T1), by means of following assessment tools :

Children: 1. Cognitive Level: Leiter 3/Griffiths III; appropriate tool will be used by evaluation of developmental level 2. Adaptive Level: Vineland Adaptive Behavior Scales, Second Edition; 3. Socio-communication skills: Early Social Communication Scales; the questionnaire Skills Socio-Conversational of the Child (Le abilità socio-conversazionali del bambino; ASCB) ; 4. Language level: Italian adaptation of "MacArthur-Bates Communicative Development Inventories". - Il Primo Vocabolario del Bambino; 5. Behavioural problem: Child Behavior Checklist; 6. Clinical improvement: Clinical Global Impression - Severity scale; Clinical Global Impression - Improvement scale

Parents: 1. Parental Stress: Parenting Stress Index-Short Form; 2. Parental Quality of Life: WHO Quality of Life