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The area of behavioural phenotype research and related clinical practice is now recognised as one of high relevance to all practitioners who help people with learning disabilities, whatever their age. Knowledge continues to accumulate rapidly regarding aspects pertaining to aetiology, likely developmental, emotional and behavioural challenges, useful multidisciplinary interventions and supports and long‐term prognosis. This paper reviews the concept, its history and recent developments, focusing on those aspects which are of particular importance to clinical and other care and support professionals and their clients. There is a continuing need for widespread dissemination of the large body of relevant information, and its application to practice in order to maximise benefits for people with learning disabilities and their families.

This paper seeks to discuss the complexity of the relationship between genotype and phenotype and highlight the importance of a greater understanding of behavioural phenotypes in genetic syndromes. The aim is to explore the developmental trajectory of the behavioural phenotypes as individuals emerge from childhood into adulthood and beyond.

Information was gathered from a search of the relevant literature over the past 20 years using Medline and PsycINFO databases in May 2010 as well as information published in textbooks on this matter.

The outcomes were considered under five areas of functioning: cognition, communication, behaviour, social functioning and propensity to psychiatric illnesses. The research thus far suggests that outcomes in behavioural phenotypes in adults are extremely variable. Individual predictions are difficult to make. However, some trends do emerge.

Findings of particular interest are the rates of attention deficit hyperactivity disorder and autism spectrum conditions and how these change over the developmental trajectory. The paper highlights the need for further research in this area and discusses the need to view behavioural phenotypes as a continuum across the lifespan.

The behavioral phenotype of fragile X syndrome (FXS) and intellectual disability (ID) proposed by Hagerman et al. (2009) was primarily based on data from male children and teens. The purpose of this study was to promote a better understanding of how this condition manifests in adults.

A total of 18 men of FXS were paired with men with Down syndrome on the basis of age and level of ID. A screening checklist was created on the basis of existing scales and the Hagerman et al. (2009) behavioral phenotype and completed by care providers.

Five of the 12 features of the phenotype were significantly more present among men with FXS than in men with Down syndrome.

This study provides partial confirmation for Hagerman et al.’s (2009) behavioral phenotype of FXS among men with moderate ID and identified some traits that warrant further investigation.

Cornelia de Lange syndrome (CdLS) is a congenital disorder characterized by distinctive facial features, growth retardation, limb abnormalities, intellectual disability, and behavioral problems. Cornelia de Lange syndrome is associated with abnormalities on chromosomes 5, 10 and X. Heterozygous point mutations in three genes (NIPBL, SMC3 and SMC1A), are responsible for approximately 50-60% of CdLS cases. CdLS is characterized by autistic features, notably excessive repetitive behaviors and expressive language deficits. The prevalence of autism spectrum disorder (ASD) symptomatology is comparatively high in CdLS. However, the profile and developmental trajectories of these ASD characteristics are potentially different to those observed in individuals with idiopathic ASD. A significantly higher prevalence of self-injury are evident in CdLS. Self-injury was associated with repetitive and impulsive behavior. This study describes the behavioral phenotype of four children with Cornelia de Lange syndrome and ASDs and rehabilitative intervention that must be implemented.

This article focuses on the consequences of having FraX‐E, the rare but well recognised variant of fragile X syndrome. The authors provide some background on the condition and report on recent research and evidence. Three case reports are outlined and the specific behavioural aspects of the syndrome are considered. The authors argue that it is important that the behavioural phenotype for FraX‐E is clearly identified and defined in order to give those with the condition relevant psychological and educational support in the future.

The purpose of this paper is to establish the value of clinical genetic diagnostics in the lives of people with an intellectual disability (ID), their families, and their primary and professional caregivers. It has been shown that psychologists are more likely to make use of the opportunities offered by clinical genetic diagnostics if they have seen the psychological benefits in their own practice. Moreover, this paper aims to promote the practice of informing people with ID, their families, and other caregivers regarding the current technological advances in genetic diagnostics, thereby allowing these patients to decide for themselves whether to utilise these opportunities.

The authors report four case studies in which the psychosocial value to each patient is pivotal.

In these four cases, it is clear the medical model can augment the social model by providing an interpretation of its meaningfulness in the lives of the people concerned.

Case studies alone can have limited scientific significance. This approach examining the significance of clinical genetic diagnosis should be studied further in larger groups.

It is hoped that psychologists and other professional caregivers will become enthused about the value of clinical genetic diagnostics and will choose to discuss the option of referral for clinical genetic diagnostics with their patients more often.

People with an ID who are seeking mental health care, and their caregivers, should be given the opportunity to take part in the decision regarding whether to use clinical genetic diagnostics, which may even have a destigmatising effect.

Quality of life may improve for people with an ID seeking mental healthcare and for their caregivers as well by opening up discussion regarding the opportunities presented by clinical genetic diagnostics. The fact that people are able to make their own choices based on their own considerations can have a destigmatising effect.

The purpose of this paper is to assess the prevalence and nature of presentation of unipolar depression in individuals with Prader-Willi syndrome (PWS).

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (2009) checklist for systematic reviews was followed where possible.

Seven studies were included in the qualitative synthesis from a total of 261 records identified. The quality of the studies was then assessed: scores for each study design ranged from between 3 and 6 of a possible score total of 6. The frequency of depression ranged between studies from 4 to 22 per cent. four studies showed over 50 per cent of patients appeared to suffer from psychotic symptoms. Low mood, anhedonia and irritability were described as features of depression, although no fixed pattern of psychopathology arose from across the studies (excluding psychosis). This review has provided evidence to suggest that depression is a frequent occurrence in the PWS population. One study found that the incidence of depression differed between the genetic subtypes, raising questions regarding the relationship between genotype and behavioural phenotypes. A high proportion of individuals with depression suffered from psychotic symptoms.

The small number of heterogeneous studies included in this study precluded meta-analysis of the results. This highlights the need for further original research in this field.

An increased awareness of the frequency of depressive symptoms within the PWS population will aid in the timely diagnosis and management of the disorder which will reduce psychiatric morbidity. The noted high proportion of psychotic symptoms associated with depression should raise the index of suspicion with clinicians and aid appropriate management decisions.

This review has provided preliminary evidence for the nature of presentation of unipolar depression in PWS. It has highlighted the possibility of an increased propensity towards depression with psychotic symptoms. There is some suggestion of a differing presentation and course of unipolar depression between the common genetic subtypes of PWS which warrants further investigation.

Attention deficit hyperactivity disorder (ADHD) is a common disorder that is highly prevalent in children and frequently persists into adulthood. The purpose of this paper is to consider the need for practitioners to be aware of the disorder.

This paper reviews quantitative genetic findings in ADHD, primarily focussing on twin studies that describe the role of genetic influences throughout the lifespan and the associated overlap between ADHD and other syndromes, disorders and traits.

This paper concludes that ADHD is a lifespan condition that shares genetic risk factors with other psychiatric, neurodevelopmental disorders and intellectual disabilities.

This paper makes the case that clinicians working in the area of intellectual disability should be fully aware of the potential impact of ADHD and its associated impairments.