Cri-du-chat

Cri-du-chat is a French phrase, which translates literally to cry-of-cat. It is also the name of a neurodevelopmental disorder. Most cases appear to stem from de novo deletion of chromatin from the short arm of chromosome 5 (5p), although in a minority of individuals (10-15%) there is evidence of parental translocations [1]. The male to female ratio is about equal. Cornish and Bramble [2] distinguished between typical cri-du-chat associated with more serious impairment and an atypical form of it associated with less serious impairment. Additional research is required to determine whether this important distinction is best conceptualized in terms of sub-types or in terms of a continuum of severity. Prevalence is about 1 in every 50,000 to 1 in every 37,000 live births [3],[4]. Perhaps because of its relatively low prevalence, the cri-du-chat syndrome has received relatively little attention from rehabilitation researchers and professionals. The aim of this editorial is to raise awareness of the cri-du-chat syndrome by providing a brief overview of the associated developmental and behavioral characteristics. We hope that this overview will stimulate interest and research into the rehabilitation of children with this syndrome. To stimulate research, we offer suggestions for two broad areas in need of empirical investigation.

In 1963, French researchers [5] described three children with a triad of characteristics that appeared to constitute a new and unique type of neurodevelopmental disorder. Perhaps the most striking characteristic, and the one that gave the syndrome its name, was the distinctive cat-like sound of the children's cry. This sound has been described as “a distinct high-pitched monochromatic cry at birth”, which is “similar to the mewing of a cat.” [4, p. 192). While this distinctive cry is highly prevalent in cases of cri-du-chat, it is important to note that it is not necessarily present in every child [2]. Still, this distinctive cat-like cry is considered a reliable and early diagnostic indictor of the syndrome because of its high prevalence and because it is not characteristic of any other disorders [4].

A second feature considered part of the cri-du-chat syndrome is significant intellectual disability [4]. However, Cornish and Bramble's [2] review of the evidence on this matter suggests considerable uncertainty as the degree of intellectual impairment of such children owing, in part, to methodological limitations of published studies. In addition, more recent evidence, which has taken into account typical and atypical sub-types, has revealed greater variability with respect to the intellectual and cognitive functioning of children with cri-du-chat syndrome [6]. Indeed it appears that not all children with the syndrome have significant intellectual disability and some even appear to demonstrate intellectual abilities close to the normal range. One implication of this identified variability is that every child should have a thorough assessment of his/her intellectual and cognitive functioning.

Various physical anomalies constitute a third feature of cri-du-chat syndrome [5]. These anomalies, clearly described by Ohr, include: (a) microcephaly, (b) increased width between the eyes, (c) a rounded moonlike face, (d) low set ears, (e) small jaw, and (f) a host of other craniofacial dysmorphia [4, p. 193]. It is unclear to what extent these physical anomalies might present attitudinal barriers or create body image and self-esteem issues. Such questions should be high on the research agenda. Good evidence on these issues is necessary to inform interventions aimed at improving social inclusion and social adjustment of children with cri-du-chat syndrome.

Of direct relevance to rehabilitation is the children's individual situation in terms of developmental, learning, and behavior problems [2],[4]. In addition to intellectual impairment, significant deficits are often observed in the children's learning abilities, language development, academic achievement, and overall adaptive behavior functioning [2],[4]. Many children also present with severe behavior problems, such as self-injury, aggressive behavior, and stereotyped movement disorder [2]. Evidence suggests that many of these developmental and behavioral problems can be linked to specific genotypes; that is, they represent behavioral phenotypes of the syndrome [2].

The myriad of developmental and behavior problems associated with cri-du-chat syndrome are likely to present significant challenges for rehabilitation professionals. To address these problems, one would need to set up at least two lines of research. The first line would consist of applied intervention research aimed at developing new and more effective intervention strategies for tackling these children's major areas of developmental deficits and behavioral excesses. For example, there seems to be an urgent need for intervention research focused on enhancing communication and language skills. Also, while little is known about the children's social skills, this too would seem to be an area where effective intervention efforts are required given that effective social interaction often requires a fair degree of communicative competency. Other relevant areas for intervention research would involve academic and adaptive behavior functioning (e.g., play, reading, self-care, vocational training). Emphasis must also be placed on research initiatives aimed at developing new and more effective intervention strategies for the treatment of severe behavior problems in children with cri-du-chat syndrome.

An obvious starting point for this proposed program of applied intervention research is to evaluate the utility of intervention strategies that have already proven effective for children with other types of neurodevelopmental disorders. There are, for example, numerous intervention strategies that have been used to develop communication skills in children with levels of intellectual disability and language impairment similar to those that one finds in children with cri-du-chat syndrome [7]. Similarly, there are effective approaches to intervention for improving adaptive behavior functioning and for reducing problem behaviors in children with developmental and behavioral characteristics, such as those of many children with cri-du-chat syndrome [8]. Can these same intervention strategies be successfully applied to children with cri-du-chat syndrome? While there is no a priori reason to suspect that the same strategies would not work with cri-du-chat syndrome, an evidence-based answer originating from systematic research in the area is still needed.

The second line of research is to make use of emerging methodologies for identifying behavioral phenotypes [2]. Duker, van Driel, and van de Bercken [9], for example, provided assessment data suggestive of distinct communicative phenotypes associated with different types of developmental disability syndromes. While discoveries of such behavioral phenotypes are increasing [2], it is rare to come across studies that have managed to successfully link evidence of a behavioral phenotype to some differentially effective intervention practice. Given recent advances in identifying behavioral phenotypes, it would seem obvious that more research of this type is bound to appear. Less obvious is whether such research will generate advances in rehabilitation to children with cri-du-chat and other types of neurodevelopmental disorders. We hope that it will and we hope that applied researchers will take up the challenge of discovering meaningful phenotype-treatment interactions. This type of research has the potential to lead to new and more effective interventions for children with cri-du-chat and other types of nuerodevelopmental disorders. One thing we can all agree on is that these children deserve the very best interventions based on the very best evidence.