Leber's congenital amaurosis: is there an autistic component?

Screening for Autism Spectrum Disorder in children and adolescents with Leber's congenital amaurosis

PURPOSE

To investigate autism spectrum disorder (ASD) indicators in children with Leber congenital amaurosis (LCA).

METHODS

Cross-sectional, correlational, and prospective study. Participants included patients aged 2 to 16 years with LCA confirmed by genetic testing. There were 20 individuals with ciliopathies (LCA cilio) and 26 with other gene mutations (LCA other). The instrument used for ASD screening was the Autism Behavior Checklist (ABC). Marginal descriptive analyses, non-parametric tests, and a linear regression model were conducted.

RESULTS

Of the 46 participants, 6 had ASD scores. There was no statistically significant correlation between the different groups (LCA cilio and LCA other) (p=0.438). There was no statistically significant correlation between age and ASD (p=0.308). However, there was a statistically significant correlation between visual acuity and ASD (p=0.008) and between male gender and ASD (p=0.025).

CONCLUSIONS

This study suggests that there is no correlation between LCA cilio, LCA other and ASD. These findings bring new insights to the existing literature, which previously lacked robust data on the relationship between LCA and ASD. These data demonstrate that visual acuity plays a crucial role in the development of children with visual impairment as poorer visual acuity is associated with a higher incidence of ASD. Based on this study, early interventions can be designed, especially for individuals without light perception, with the aim of maximizing their developmental outcomes. Furthermore, such data indicates that any improvement in visual acuity outcomes in treatment clinical trials become relevant for child development.

Considerations for the identification of autism spectrum disorder in children with vision or hearing impairment: A critical review of the literature and recommendations for practice

OBJECTIVE

There is higher risk for autism spectrum disorder (ASD) across many pediatric neurological conditions characterized by vision impairment or hearing loss. Early and accurate identification of ASD is imperative in promoting access to appropriate and early evidenced-based intervention; however, differential diagnosis can be particularly challenging in children with sensory impairment given the heterogeneity of ASD combined with the impact of vision impairment or hearing loss/deafness on development and behavior. A neuropsychologist's unique expertise and appreciation of the interplay between sensory and behavioral manifestations can be valuable for making an early and accurate ASD diagnosis in children who are blind/visually impaired or deaf/hard-of-hearing. This article highlights clinical considerations when identifying ASD within the context of vision impairment or hearing loss/deafness.

METHOD

We discuss clinical considerations for the early identification of ASD in children who are blind/visually impaired and deaf/hard-of-hearing. Information presented in the article is based on a critical review of the literature and the expertise of the author group.

CONCLUSION

Ongoing development of clinical expertise and evidence-based assessment methods are important when informing the early differential diagnosis of ASD in individuals with sensory impairment. Accurate identification is also vital for the development of targeted interventions across the lifespan.

Cortical Visual Impairments and Learning Disabilities

Medical advances in neonatology have improved the survival rate of premature infants, as well as children who are born under difficult neurological conditions. As a result, the prevalence of cerebral dysfunctions, whether minimal or more severe, is increasing in all industrialized countries and in some developing nations. Whereas in the past, ophthalmological diseases were considered principally responsible for severe visual impairment, today, all recent epidemiological studies show that the primary cause of blindness and severe visual impairment in children in industrialized countries is now neurological, with lesions acquired around the time of birth currently comprising the commonest contributor. The resulting cortical or cerebral visual impairments (CVIs) have long been ignored, or have been confused either with other ophthalmological disorders causing low vision, or with a range of learning disabilities. We present here the deleterious consequences that CVI can have upon learning and social interaction, and how these can be given behavioral labels without the underlying visual causes being considered. We discuss the need to train and inform clinicians in the identification and diagnosis of CVI, and how to distinguish the diagnosis of CVI from amongst other visual disorders, including the specific learning disorders. This is important because the range of approaches needed to enhance the development of children with CVI is specific to each child's unique visual needs, making incorrect labeling or diagnosis potentially detrimental to affected children because these needs are not met.

A Multidimensional, Multisensory and Comprehensive Rehabilitation Intervention to Improve Spatial Functioning in the Visually Impaired Child: A Community Case Study

Congenital visual impairment may have a negative impact on spatial abilities and result in severe delays in perceptual, social, motor, and cognitive skills across life span. Despite several evidences have highlighted the need for an early introduction of re-habilitation interventions, such interventions are rarely adapted to children’s visual capabilities and very few studies have been conducted to assess their long-term efficacy. In this work, we present a case study of a visually impaired child enrolled in a newly developed re-habilitation intervention aimed at improving the overall development through the diversification of re-habilitation activities based on visual potential and developmental profile, with a focus on spatial functioning. We argue that intervention for visually impaired children should be (a) adapted to their visual capabilities, in order to increase re-habilitation outcomes, (b) multi-interdisciplinary and multidimensional, to improve adaptive abilities across development, (c) multisensory, to promote the integration of different perceptual information coming from the environment.

Autistic-Like Features in Visually Impaired Children: A Review of Literature and Directions for Future Research

There remains great interest in understanding the relationship between visual impairment (VI) and autism spectrum disorder (ASD) due to the extraordinarily high prevalence of ASD in blind and visually impaired children. The broad variability across individuals and assessment methodologies have made it difficult to understand whether autistic-like symptoms shown by some children with VI might reflect the influence of the visual deficit, or represent a primary neurodevelopmental condition that occurs independently of the VI itself. In the absence of a valid methodology adapted for the visually impaired population, diagnosis of ASD in children with VI is often based on non-objective clinical impression, with inconclusive prevalence data. In this review, we discuss the current state of knowledge and suggest directions for future research.

[Autism spectrum symptoms in children with congenital blindness]

Autism spectrum symptoms in children with congenital blindness Abstract. Objective: Previous studies reported increased rates of autistic symptoms in children with impaired visual abilities (IV). However, the application of existing screening questionnaires for autism spectrum disorders (ASD) proved problematic, as intact visual abilities are typically required. The current study examines the general applicability of three autism-screening questionnaires in children with congenital blindness. Methods: Autistic symptoms were assessed in 15 children with congenital blindness, 15 children with ASD (without IV), and 20 typically developing controls (aged from 8 to 14 years), using the Social Communication Questionnaire, the Marburg Rating Scale for Asperger's Syndrome, and the Social Responsiveness Scale. Results: Items assessing motor, mimic/gesture-related, or joint attention deficits were identified as highly prevalent in children with congenital blindness. These children scored, in general, higher on ASD-screening questionnaires than typically developing controls but lower than sighted children with ASD. Depending on the screening questionnaire used, between 23 % and 67 % of the sample with congenital blindness reached clinical cutoff scores for ASD. SRS total score was negatively correlated to cognitive empathy and verbal IQ in those children. Conclusions: Mothers of children with congenital blindness reported increased autistic symptoms in ASD-screening questionnaires. ASD and IV might share a broad range of symptoms. Future development and validation of screening instruments specifically adapted to the needs of persons with impaired visual abilities seem necessary.

The development of vision between nature and nurture: clinical implications from visual neuroscience

BACKGROUND

Vision is an adaptive function and should be considered a prerequisite for neurodevelopment because it permits the organization and the comprehension of the sensory data collected by the visual system during daily life. For this reason, the influence of visual functions on neuromotor, cognitive, and emotional development has been investigated by several studies that have highlighted how visual functions can drive the organization and maturation of human behavior. Recent studies on animals and human models have indicated that visual functions mature gradually during post-natal life, and its development is closely linked to environment and experience.

DISCUSSION

The role of vision in early brain development and some of the neuroplasticity mechanisms that have been described in the presence of cerebral damage during childhood are analyzed in this review, according to a neurorehabilitation prospective.

Autism in Children With Cerebral and Peripheral Visual Impairment: Fact or Artifact?

The aim of this study was to evaluate the occurrence and clinical characteristics of autism spectrum disorder in visually impaired children. In total, 273 participants, 214 with cerebral causes of vision impairment and 59 with peripheral causes, were assessed using multiple assessment methods and adapted for individuals with vision loss. We found that autism spectrum disorder was more prevalent in the visually impaired compared to general population, and that the prevalence varied according to the type of visual disorder (2.8% for cerebral and 8.4% for peripheral visual impairment). In subjects with cerebral visual impairment, the presence of autistic symptoms was consistent with the diagnosis of autism spectrum disorder. In children with peripheral visual impairment, certain symptoms related to visual loss overlapped with the clinical features of autism spectrum disorder, thus making clinical diagnosis more challenging. The development of assessment tools that take into account the type and level of visual impairment and validation testing in a larger population sample are needed in order to confirm these initial findings regarding the diagnosis of autism spectrum disorder in visually impaired children.

Children with blindness - major causes, developmental outcomes and implications for habilitation and educational support: a two-decade, Swedish population-based study

PURPOSE

The aim was to describe the population of children with congenital or early infancy blindness in Sweden, with regard to causes of blindness and prevalence of neurodevelopmental impairments.

METHODS

Medical, psychological and pedagogical records of Swedish children with congenital or early infancy blindness (total blindness or light perception at the most) born in 1988-2008 were analysed regarding year of birth, gender, cause of blindness, gestational age, associated neurological disorders/syndromes, associated neurodevelopmental impairments, cognitive level and type of school placement.

RESULTS

A total of 150 individuals, 80 girls and 70 boys, were identified, corresponding to a prevalence of 7/100 000. Five causes of blindness dominated, constituting 76% of all represented aetiologies: retinopathy of prematurity (ROP), optic nerve hypoplasia (ONH), Leber congenital amaurosis (LCA), optic nerve atrophy (ONA) and microphthalmia/anophthalmia. Nearly three of four children in the study population had at least one additional disability besides blindness; the most common being intellectual disability (ID) and autism spectrum disorder (ASD). More than half of the population had more than one additional disability. Autism spectrum disorder (ASD) was most common in children with ONH, ROP, LCA and microphthalmia/anophthalmia.

CONCLUSION

In children born within the last decades, isolated blindness is uncommon and the rate of multidisabilities is high. Autism spectrum disorder (ASD) seems to be more strongly associated with specific aetiological subgroups. Further development of the support to families and schools should be based on knowledge about the considerable heterogeneity of the population of children with blindness, and the common occurrence of coexisting neurodevelopmental disorders, especially ID and ASD.

Autism assessment in children with optic nerve hypoplasia and other vision impairments

AIM

This study examined the utility of standard autism diagnostic measures in nine children (aged 5-9y) with severe vision impairment and a range of social and language functioning.

METHOD

The Autism Diagnostic Observation Schedule (ADOS) and the Autism Diagnostic Interview, Revised (ADI-R) were systematically modified and used to assess symptoms of autism in children with vision less than or equal to 20/800, the majority of whom had optic nerve hypoplasia. The results of the assessments, including analysis of symptom patterns, were compared with expert autism diagnoses.

RESULTS

Modified autism measures demonstrated good agreement with clinical diagnoses. Symptoms found to be most and least reliable in discriminating autism from behaviors common to most children with congenital vision impairment are described. Comparisons of current behavior with parent-reported behaviors from a younger age suggested that some symptoms of autism in very young children who are congenitally blind may improve with age.

INTERPRETATION

The ADOS and ADI-R are useful for clinical assessment and for advancing research efforts to understand autism symptoms in children with vision impairment. However, some autistic symptoms in very young children may change over time, and developmental changes should be closely monitored.

The identification and measurement of autistic features in children with septo-optic dysplasia, optic nerve hypoplasia and isolated hypopituitarism

This study aimed to highlight the occurrence of autism spectrum disorders (ASDs) in children with septo-optic dysplasia (SOD) and optic nerve hypoplasia (ONH). A cross-sectional study was designed, including 28 children with SOD and 14 children with ONH. Clinician diagnosis of ASD was reported in 14 children. The Social Communication Questionnaire (SCQ) reported that 23 children met the cut-off point for ASD, and 9 children met the cut-off point for autism. Greater levels of intellectual disability and visual loss were reported in children with ASD in comparison to those without ASD, but, of the two, intellectual disability was a better predictor for ASD. The SCQ lost its sensitivity and specificity in children who had greater visual loss which highlights a requirement for a measure that is sensitive to visual loss. It is also recommended that children with SOD/ONH would benefit from routine screening for ASDs.

Autism spectrum disorders: the quest for genetic syndromes

Autism spectrum disorders (ASD) are a heterogeneous group of neurodevelopmental disabilities with various etiologies, but with a heritability estimate of more than 90%. Although the strong correlation between autism and genetic factors has been long established, the exact genetic background of ASD remains unclear. A number of genetic syndromes manifest ASD at higher than expected frequencies compared to the general population. These syndromes account for more than 10% of all ASD cases and include tuberous sclerosis, fragile X, Down, neurofibromatosis, Angelman, Prader-Willi, Williams, Duchenne, etc. Clinicians are increasingly required to recognize genetic disorders in individuals with ASD, in terms of providing proper care and prognosis to the patient, as well as genetic counseling to the family. Vice versa, it is equally essential to identify ASD in patients with genetic syndromes, in order to ensure correct management and appropriate educational placement. During investigation of genetic syndromes, a number of issues emerge: impact of intellectual disability in ASD diagnoses, identification of autistic subphenotypes and differences from idiopathic autism, validity of assessment tools designed for idiopathic autism, possible mechanisms for the association with ASD, etc. Findings from the study of genetic syndromes are incorporated into the ongoing research on autism etiology and pathogenesis; different syndromes converge upon common biological backgrounds (such as disrupted molecular pathways and brain circuitries), which probably account for their comorbidity with autism. This review paper critically examines the prevalence and characteristics of the main genetic syndromes, as well as the possible mechanisms for their association with ASD.

Reach on sound: a key to object permanence in visually impaired children

BACKGROUND

The capacity to reach an object presented through sound clue indicates, in the blind child, the acquisition of object permanence and gives information over his/her cognitive development.

AIM

To assess cognitive development in congenitally blind children with or without multiple disabilities.

STUDY DESIGN

Cohort study.

SUBJECTS

Thirty-seven congenitally blind subjects (17 with associated multiple disabilities, 20 mainly blind) were enrolled.

OUTCOME MEASURES

We used Bigelow's protocol to evaluate "reach on sound" capacity over time (at 6, 12, 18, 24, and 36 months), and a battery of clinical, neurophysiological and cognitive instruments to assess clinical features.

RESULTS

Tasks n.1 to 5 were acquired by most of the mainly blind children by 12 months of age. Task 6 coincided with a drop in performance, and the acquisition of the subsequent tasks showed a less agehomogeneous pattern. In blind children with multiple disabilities, task acquisition rates were lower, with the curves dipping in relation to the more complex tasks.

CONCLUSIONS

The mainly blind subjects managed to overcome Fraiberg's "conceptual problem"--i.e., they acquired the ability to attribute an external object with identity and substance even when it manifested its presence through sound only--and thus developed the ability to reach an object presented through sound. Instead, most of the blind children with multiple disabilities presented poor performances on the "reach on sound" protocol and were unable, before 36 months of age, to develop the strategies needed to resolve Fraiberg's "conceptual problem".

Developing a schedule to identify social communication difficulties and autism spectrum disorder in young children with visual impairment

Available observational tools used in the identification of social communication difficulties and diagnosis of autism spectrum disorder (ASD) rely partly on visual behaviours and therefore may not be valid in children with visual impairment. A pilot observational instrument, the Visual Impairment and Social Communication Schedule (VISS), was developed to aid in identifying social communication difficulties and ASD in young children with visual impairment affected by congenital disorders of the peripheral visual system (disorders of the globe, retina, and anterior optic nerve). The VISS was administered to 23 consecutive children (age range 1 y 9 mo-6 y 11 mo, mean 4 y 1 mo [SD 1.6]; 12 males, 11 females) with visual impairment (nine with severe and 14 with profound visual impairment). Item analysis was carried out by fit of the items to the Rasch model. Validity of the VISS was explored by comparison with the Childhood Autism Rating Scale (CARS) score, and the clinical ASD diagnosis (n=9). Correlation between the VISS and CARS total scores was highly significant (Spearman's rho=-0.89; p=0.01). Below threshold rating on the VISS (score of 35) showed good agreement with the clinical ASD diagnosis (sensitivity 89%, specificity 100%). This preliminary study shows the VISS to be a promising schedule to aid the identification of ASD in young children with visual impairment.

Leber congenital amaurosis: genes, proteins and disease mechanisms

Leber congenital amaurosis (LCA) is the most severe retinal dystrophy causing blindness or severe visual impairment before the age of 1 year. Linkage analysis, homozygosity mapping and candidate gene analysis facilitated the identification of 14 genes mutated in patients with LCA and juvenile retinal degeneration, which together explain approximately 70% of the cases. Several of these genes have also been implicated in other non-syndromic or syndromic retinal diseases, such as retinitis pigmentosa and Joubert syndrome, respectively. CEP290 (15%), GUCY2D (12%), and CRB1 (10%) are the most frequently mutated LCA genes; one intronic CEP290 mutation (p.Cys998X) is found in approximately 20% of all LCA patients from north-western Europe, although this frequency is lower in other populations. Despite the large degree of genetic and allelic heterogeneity, it is possible to identify the causative mutations in approximately 55% of LCA patients by employing a microarray-based, allele-specific primer extension analysis of all known DNA variants. The LCA genes encode proteins with a wide variety of retinal functions, such as photoreceptor morphogenesis (CRB1, CRX), phototransduction (AIPL1, GUCY2D), vitamin A cycling (LRAT, RDH12, RPE65), guanine synthesis (IMPDH1), and outer segment phagocytosis (MERTK). Recently, several defects were identified that are likely to affect intra-photoreceptor ciliary transport processes (CEP290, LCA5, RPGRIP1, TULP1). As the eye represents an accessible and immune-privileged organ, it appears to be uniquely suitable for human gene replacement therapy. Rodent (Crb1, Lrat, Mertk, Rpe65, Rpgrip1), avian (Gucy2D) and canine (Rpe65) models for LCA and profound visual impairment have been successfully corrected employing adeno-associated virus or lentivirus-based gene therapy. Moreover, phase 1 clinical trials have been carried out in humans with RPE65 deficiencies. Apart from ethical considerations inherently linked to treating children, major obstacles for the treatment of LCA could be the putative developmental deficiencies in the visual cortex in persons blind from birth (amblyopia), the absence of sufficient numbers of viable photoreceptor or RPE cells in LCA patients, and the unknown and possibly toxic effects of overexpression of transduced genes. Future LCA research will focus on the identification of the remaining causal genes, the elucidation of the molecular mechanisms of disease in the retina, and the development of gene therapy approaches for different genetic subtypes of LCA.