Fragile X Syndrome (FXS) is the main hereditary cause of intellectual disability (ID) and the most common, known monogenic disability (Kerr et al., 2015; Klusek et al., 2014). It is caused by a mutation in the FMR1 gene, located on the X chromosome. The prevalence rates provided by the literature vary considerably, with an incidence in men ranging from 1 in 2,500 to 1 in 7,000, and in women from 1 in 4,000 to 1 in 11,000. In Europe, the overall prevalence of the disease is estimated at 20 out of every 100,000 inhabitants (Chevreul et al., 2016; Hunter et al., 2014). Children and adolescents with FXS typically have moderate to severe intellectual disability < 55 (Raspa et al., 2017).

In addition to cognitive delay, research has reported that children and adolescents with FXS have an increased risk of behavioral and emotional disorders compared to peers with typical development (TD). Neuropsychiatric phenotypes include a high risk of autism spectrum disorders (Chevreul et al., 2015; Chromik et al., 2019; Hare et al., 2016; Klusek et al. 2014; Moskowitz & Jones, 2015; Thurman et al., 2014), as well as other behavioral symptoms (Raspa et al., 2017): a) between 36% and 93% of individuals with FXS have associated hyperactivity and attention deficit (Angriman et al., 2015; Hare et al., 2016; Hartley et al., 2012; Thurman et al., 2014; Wheeler et al., 2008); b) around 70% of individuals with FXS have emotional problems, such as anxiety and depression (Bailey et al., 2012; Cordeiro et al., 2011; Roberts et al., 2014; Wheeler et al., 2014), and often show characteristics of social anxiety, including gaze avoidance, delay in initiating social interactions, and difficulty forming meaningful peer relationships (Holsen et al., 2008); and c) other distinctive features of FXS are behavior problems, including tactile defensiveness, hand flapping, poor eye contact, tantrums, perseveration, hyperarousal to sensory stimuli, and impulsivity (Muller et al., 2018; Symons et al., 2010). More than 30% of children and adolescents with FXS have committed acts of aggression, with their parents or caregivers even requiring medical attention in some cases (Bailey et al., 2012). Self-injury (e.g., hand and finger biting) is also common in about 79% of individuals with FXS (Symons et al., 2010). For example, Wheeler et al. (2016) pointed out in their study that 83% of females and 92% of males between 3 and 67 years old with FXS had participated in at least one aggressive act. More than a third of the males (38%) and 18% of the females had participated in an aggression serious enough to be diagnosed or treated for this reason (30% had caused injuries to their caregivers, and 22% had caused injuries to their peers or friends). The most common form of physical aggression was hitting, pushing, or kicking (54% of males and 31% of females). Less common was bullying (8% of males and 10% of females) or threats to others (19% of males and 7% of females). Behaviors such as tantrums, defiance, and arguments affect approximately 50% of all the age and sex groups. These difficulties may continue into adulthood (Chromik et al., 2019; Frolli et al., 2015).

This phenotype has a clear impact on families because it increases parenting demands and stress, influences family functioning, and requires families to reorganize and adapt their routines (Burke & Heller, 2016; Gardiner et al., 2018; Schlebusch et al., 2016; Summers et al., 2005; Wheeler et al., 2008).

Although the link between FXS and lower parental wellbeing has been well established, including more stress, higher levels of depression, and health problems (Hayes & Watson, 2013; Miodrag et al., 2015), the degree to which FXS might affect broader aspects of family functioning has been less investigated.

In this regard, in the study by Lewis et al. (2006), mothers of children with FXS claimed to have less privacy than mothers of children with other types of disabilities. In addition, Hartley et al. (2012) found that 15.9% of parents with FXS children reported depressive symptoms that required clinical intervention, compared to 30.4% of parents of children with ASD and 6.8% of parents of children with DS. Thus, parents of children with FXS had higher wellbeing than parents of children with ASD and lower than parents of children with DS.

Behavior problems are considered a strong predictor of parental stress. According to Cantwell et al. (2015), a child who exhibits challenging behavior in a public place can be very problematic and distressing for parents because of feelings of perceived stigma (feeling judged), hostile encounters with the general public, feelings of isolation, and a sense of impotence.

A prospective study conducted in Germany between 2013 and 2016 observed 75 people with FXS from two to 82 years old in their social environment, showing the considerable burden experienced by the parents and the person with FXS. The main caregivers were either the parents or one parent in the case of 62 patients (82.7%). The fact that in 17 cases (22.7%) there were siblings with FXS means that these families had an additional burden (Haessler et al., 2016).

In addition, families of individuals with FXS require significant resources of a non-medical nature that have a considerable economic cost, especially in the case of children (Bailey et al., 2012; Ouyang et al., 2014). In France, the estimated annual direct cost per patient per year is €25,800 (Chevreul et al., 2015).

In turn, a family environment with high stress levels affects a child’s self-regulatory development and social competence. That is, the impact is bidirectional and affects the quality of life of the entire family system (Summers et al., 2005).

In general, therefore, higher stress levels, lower general wellbeing, a greater prevalence of health problems (depression and anxiety), poorer social relationships, negative parenting feelings, less marital satisfaction, and greater economic and care demands have been found (Cantwell et al., 2015; Chan et al., 2017; Hall et al., 2016; Hartley et al., 2012; Minnes et al., 2015; Patton et al., 2018; Wheeler et al., 2016; Wheeler et al., 2008; Woodman et al., 2015).

However, research is not conclusive because some positive effects also appear (Berglund et al., 2015): better parent-child interaction, more family cohesion, and a greater sense of purpose in life and of priorities (Grein & Glidden, 2015; Wheeler et al., 2008). Resilience, coping strategies, family routines, financial resources, and social support seem to be “protective” factors against the negative effects mentioned, and they contribute to wellbeing by improving the quality of life, not only of the disabled child, but also of the whole family (Grein & Glidden, 2015; Jess et al., 2018; Migerode et al., 2012; Minnes et al., 2015; Norling & Broberg, 2013; Schlebusch et al., 2016; Usher et al., 2018), including the siblings (Iriarte et al., 2015; McHale et al., 2016; Rossetti & Hall, 2015).

The aims of this study were to describe levels of emotional and behavioral difficulties in a Spanish sample of children and adolescents with FXS and analyze the impact of having a child with FXS on different aspects of family functioning. The results of the study contribute to the knowledge about the behavioral phenotype of children and adolescents with FXS and, specifically, the impact of FXS on family functioning.

Overall, our results found that between 17% and 66% of children and adolescents with FXS displayed significant behavioral and emotional disturbances. In this regard, children and adolescents with FXS displayed more conduct problems, hyperactivity, peer problems, and emotional problems, as well as fewer prosocial behaviors. Our results are consistent with previous literature (Bailey, 2012; Cordeiro et al., 2011; Haessler, 2016; Newman et al., 2015; Roberts et al., 2014). In general, a defined pattern of problem behaviors, including hyperactivity, inattention, autistic features, and aggression, along with comorbid anxiety, has emerged for this population, and this pattern is estimated to occur in up to 86% of males with FXS (Low Kapalu & Garstein, 2016).

These behavioral and emotional difficulties can negatively impact the health and safety of the individual involved and others (Hall et al., 2016; Minnes et al., 2015; Ouyang et al., 2014; Suzumura, 2015; Wheeler et al., 2016; Woodman et al., 2015) because they can produce negative feelings in parents and siblings and affect family economy and coexistence with a child with FXS. In fact, once behavioral and emotional problems were covaried, our results showed that families with FXS experienced a greater negative impact on feelings about parenting, finances, siblings, and the degree of difficulty of living with a child or adolescent with FXS. In general, our results are similar to those of other studies (Haessler et al., 2016; Johnston et al., 2003; Lewis et al., 2006; Raspa et al. 2016).

First, parents of children with FXS in our study showed more negative feelings about parenting than parents in the control group. Haessler et al. (2016) found that in a group of 64 patients with FXS, 39.1% of parents reported low/normal stress, 34.4% high, and 78.1% very high. In the study by Johnston et al. (2003), 25% of mothers of children with FXS felt stress due to isolation and lack of parental competence. Problems and concerns about parenting and family relationships are affected by the diagnostic status of the child, and are greater in the case of parents of children with FXS (Lewis et al., 2006; Raspa et al., 2016).

Second, parents also point out the impact that caring for a child with FXS has on their finances. Emerson et al. (2006), in a British national study (Department for Work and Pensions: Families & Children Study - FACS), found that mothers (n = 6,954) with at least one dependent child had a higher risk of low wellbeing (less happiness, self-esteem, and self-efficacy) due to greater economic difficulties. These additional burdens are also predictors of family distress (Minnes et al., 2015). Ouyang et al. (2014) compared family’s financial and employment impact of having a child with FXS, autism spectrum disorder (ASD), or intellectual disabilities (ID), and found that higher percentages of caregivers of children with FXS reported a negative family financial (60%) and employment (40%) impact.

Bailey et al. (2012), in their study with 350 caregivers, found that most families reported that FXS had at least some financial impact on the family, and caregivers had to take an average of 19.4 hours off work each month to care for their child’s needs. Regarding economic costs, the studies by Chevreul et al. (2015) and Chevreul et al. (2016) include all types of costs associated with FXS, including the least visible ones, such as informal costs and loss of job productivity. In addition, it is the first study to estimate both the cost incurred by FXS and the impact on HRQOL (health-related quality of life) for FXS patients and caregivers. It highlights the high cost of the disease from a social perspective, despite its low prevalence, and that its life expectancy is similar to that of the rest of the population. Some of the data collected indicate that lifetime costs of FXS patients range from €1,113,000 for males to €620,000 for females, and the annual cost per patient ranges from €8,208 to €25,800.

Third, our results also indicate that having a child with FXS has a negative influence on siblings. They often have to help more with housework, they are ashamed of their sibling’s behavior, or they invite their friends to their home less often. O’Neill and Murray (2016) found that siblings observed incoherent and negative parenting styles in their parents.

Fourth, in our study, parents point out that it is very difficult to live with a child with FXS. According to Rodas et al. (2016), there are differences between parenting practices of parents of children with and without ID. Children with disabilities have an increased risk of developing other (internalizing) psychiatric disorders and of receiving negative parental education associated with these problems, which can create a vicious cycle.

Fifth, in our study, however, there were no significant differences between groups in their social life. Some studies (Muller et al., 2018; Mulroy et al., 2008) reported restrictions on family activities due to a child’s disability. However, although no significant differences were found between groups in social life, group means are quite different: 9.87 for FXS and 1.33 for the comparison group. The reason for this may be that the standard deviation is quite large in the FXS group (SD = 7.95).

Sixth, in our study, there are no significant differences related to positive feelings (see Table 3), and this result may be due to high self-esteem in the group of parents with children with FXS. As Cantwell et al. (2015) noted, the higher the parents’ self-esteem, the greater their resilience and psychological health, because self-esteem buffers the impact of stress on psychological wellbeing. These results are also supported by Wheeler et al. (2008), who found that perceived quality of life of mothers of children with FXS was not different from that of the general population. Instead of being overwhelmed by their child’s disability, they felt full of energy and support. The hope factor appears in this study as a predictor of quality of life. Parents’ hope factor, associated with adaptive coping strategies, is related to a warmer parenting style and a more cohesive and active family environment.

Finally, families with FXS displayed more family adaptability (mean = 38.98) and cohesion (mean = 43.28) than those in the comparison group. In this regard, Baker et al. (2012) also reported higher levels of cohesion in families of adolescents and adults with FXS than what had been previously reported for families of individuals with developmental disabilities. Johnston et al. (2003) indicated that greater family cohesion and support are related to less stress and and feelings of isolation in the study mothers, as well as greater confidence in their parenting skills.

It is important to note the limitations of our study. First, the majority of respondents were mothers (77.2% in the FXS group and 67.5% in the comparison group). Although this is common in research (Allison & Campbell, 2015; Ly & Goldberg, 2014; Ouyang et al., 2014; Usher et al., 2018), not all family members experience similar effects as a result of being a relative of a child with a disability (Hastings et al., 2005). Problems experienced by mothers may not reflect those of other family members. Second, our study is cross-sectional in nature, and so it would be useful to examine longitudinal data in FXS because previous studies suggest the possibility of a decline in the reported positive impact over time (see Blancher et al., 2013; Raspa et al., 2017). Third, respondents were members of FXS family associations, and samples drawn from these associations may not be representative of the total population affected by FXS. Finally, findings may not be generalizable outside Spain.

In summary, our conclusions are:

Behavioral and emotional difficulties shown by children and adolescents with FXS in our study have a negative impact on parents and siblings, generating negative feelings and affecting family’s economy and coexistence with the child with FXS.

Knowing the impact of having a child with FXS on the family allows us to identify factors susceptible to intervention that can contribute to improving the welfare of the person with FXS and his/her family. This information can help to design appropriate management strategies and services that meet the needs of affected families, thus reducing vulnerability and increasing resilience in the long term.

It is important that this intervention be carried out as early as possible in order to improve the adaptive behavior of these children regarding issues specific to the syndrome, such as emotional regulation, social anxiety, or behavior problems. In fact, the literature emphasizes that behavior management is one of the aspects that most affects mental health, depression, stress, and anxiety in the parents of these children.

In this regard, we know that parental support programs focusing on behavior management are the key to moderating the psychological impact. These programs not only improve skills of children affected by FXS – a definite asset for independence in adulthood – but also the adaptability and mental health of their parents, who are no longer isolated thanks to these support groups.

Likewise, it is essential to promote family group cohesion because this is another variable that has a buffering effect on the negative psychological impact. Thus, it is necessary to ensure that fathers cease to be only “a shadow” of mothers. Encouraging fathers’ participation can lead to greater family competence, reduced parental stress, and less physical and emotional burden for mothers, as well as greater adaptive skills for children.

Support for families of children with FXS should adopt a family-centered approach that recognizes that parents are affected by the nature of their child’s disability and that the psychological wellbeing of one of the parents is linked to the psychological well-being of the child. Therefore, the best intervention recognizes the importance of interconnections among family members in promoting positive wellbeing within the family and fostering a strong family system.

Another variable to consider is family’s socioeconomic position because this factor can moderate the relationship between the child’s disability and stress. It is advisable to identify family subgroups that are most likely to experience stress for this reason.

Finally, supporting parents in the process of regulating their emotions is crucial because the more effective they are in focusing on positive aspects of their experiences with their children, the more successful they can be in defending them and experiencing better family quality of life. Intervention programs must promote parents’ self-esteem in order to improve their psychological health and resilience, thus buffering the impact of stress, in addition to increasing hope and positive expectations, which, in turn, foster a warmer and more protective parenting style that is cohesive and active in the family group.