Epilepsy and neurodevelopmental disorders of language

Resting-state EEG alpha rhythm spectral power in children with specific language impairment: a cross-sectional study

PURPOSE

This study investigated EEG alpha rhythm spectral power in children with Specific Language Impairment (SLI) and compared it to typically developing children to better understand the electrophysiological characteristics of this disorder. Specifically, we explored resting-state EEG, because there are studies that point to it being linked to speech and language development.

METHODS

EEG recordings of 30 children diagnosed with specific language impairment and 30 typically developing children, aged 4.0-6.11 years, were carried out under eyes closed and eyes open conditions. Differences in alpha rhythm spectral power in relation to brain topography and experimental conditions were calculated.

RESULTS

In the eyes closed condition, alpha rhythm spectral power was statistically significantly lower in children with specific language impairment in the left temporal (T5) and occipital electrodes (O1, O2) than in typically developing children. In the eyes open condition, children with SLI showed significantly lower alpha rhythm spectral power in the left temporal (T3, T5), parietal (P3, Pz), and occipital electrodes (O1, O2). There were no statistically significant differences between the groups in relation to the relative change (the difference between average alpha rhythm spectral power during eyes closed condition and average alpha rhythm spectral power during eyes open condition divided by average alpha rhythm spectral power during eyes closed condition) in the alpha rhythm spectral power between the conditions.

CONCLUSION

Lower alpha rhythm spectral power in the left temporal, left, midline parietal, and occipital brain regions could be a valuable electrophysiological marker in children with SLI. Further investigation is needed to examine the connection between EEG alpha spectral power and general processing and memory deficits in patients with SLI.

Warped rhythms: Epileptic activity during critical periods disrupts the development of neural networks for human communication

It is well established that temporal lobe epilepsy-the most common and well-studied form of epilepsy-can impair communication by disrupting social-emotional and language functions. In pediatric epilepsy, where seizures co-occur with the development of critical brain networks, age of onset matters: The earlier in life seizures begin, the worse the disruption in network establishment, resulting in academic hardship and social isolation. Yet, little is known about the processes by which epileptic activity disrupts developing human brain networks. Here we take a synthetic perspective-reviewing a range of research spanning studies on molecular and oscillatory processes to those on the development of large-scale functional networks-in support of a novel model of how such networks can be disrupted by epilepsy. We seek to bridge the gap between research on molecular processes, on the development of human brain circuitry, and on clinical outcomes to propose a model of how epileptic activity disrupts brain development.

[Speech and language neurodevelopmental disorders in epilepsy: pathophysiologic mechanisms and therapeutic approaches]

Speech and language development may be impaired in all forms of epilepsy involving specialized functional areas in the dominant cerebral hemisphere and their connections. The concept of epilepsy-aphasia clinical spectrum was recently proposed, but the notion of aphasia is quite conditional here as many of these patients demonstrate disorders of speech and language development from their infancy. Those forms of epilepsy are considered as continuum from the most severe Landau-Kleffner syndrome (LKS) and epilepsy with continuous spike-and-wave during sleep (CSWS) (also indicating as electrical status epilepticus during sleep - ESES) to intermediate epilepsy-aphasia disorders (with incomplete correspondence to diagnostic criteria of LKS and epilepsy with CSWS). The mild end of the spectrum is represented by benign childhood epilepsy with centrotemporal spikes (rolandic), which is often associated with speech and language disorders. The importance of genetic factors is discussed, including mutations in SRPX2, GRIN2A and other genes. The perspectives of individualized pharmacotherapy in epilepsy, co-morbid with neurodevelopmental disorders or impairments of speech and language development, are depending on the progress in genetic studies. In the new generation of antiepileptic drugs the positive influence on neuroplasticity mechanisms and higher cerebral functions are supposed for levetiracetam.

The Clinical Spectrum of Benign Epilepsy with Centro-Temporal Spikes: a Challenge in Categorization and Predictability

Benign epilepsy with centro-temporal spikes (BECTS) is the most common type of focal epilepsy in children; it is age-dependent and presumably genetic. Traditionally, children with BECTS have a very good prognosis, even without medical treatment, and are thought to show no neurological symptoms or cognitive deficits. However, many previous studies have shown that BECTS can present with various clinical and electroencephalographic characteristics that are commonly associated with neuropsychological deficits, including linguistic, cognitive, and behavioral impairment. The degree of the neuropsychological deficits appears to depend on the sleep cycle and the localization of epileptiform discharges. Furthermore, based on neurobiological studies, a complex interplay between the processes of brain maturation and the involvement of genes that confer susceptibility may contribute to a variety of different childhood epileptic syndromes with various neuropsychological deficits. Thus, BECTS, atypical benign focal epilepsy during childhood, status epilepticus of BECTS, Landau-Kleffner syndrome, and epileptic encephalopathy with continuous spike-and-wave during sleep are all considered different entities, but are part of a single spectrum of disorders. In clinical practice, we have to consider BECTS as benign only when there are no or only mild neuropsychological deficits before medical treatment.

A microRNA-328 binding site in PAX6 is associated with centrotemporal spikes of rolandic epilepsy

Objective

Rolandic epilepsy is a common genetic focal epilepsy of childhood characterized by centrotemporal sharp waves on electroencephalogram. In previous genome‐wide analysis, we had reported linkage of centrotemporal sharp waves to chromosome 11p13, and fine mapping with 44 SNPs identified the ELP4‐PAX6 locus in two independent US and Canadian case–control samples. Here, we aimed to find a causative variant for centrotemporal sharp waves using a larger sample and higher resolution genotyping array.

Methods

We fine‐mapped the ELP4‐PAX6 locus in 186 individuals from rolandic epilepsy families and 1000 population controls of European origin using the Illumina HumanCoreExome‐12 v1.0 BeadChip. Controls were matched to cases on ethnicity using principal component analysis. We used generalized estimating equations to assess association, followed up with a bioinformatics survey and literature search to evaluate functional significance.

Results

Homozygosity at the T allele of SNP rs662702 in the 3′ untranslated region of PAX6 conferred increased risk of CTS: Odds ratio = 12.29 (95% CI: 3.20–47.22), P = 2.6 × 10⁻⁴ and is seen in 3.9% of cases but only 0.3% of controls.

Interpretation

The minor T allele of SNP rs662702 disrupts regulation by microRNA‐328, which is known to result in increased PAX6 expression in vitro. This study provides, for the first time, evidence of a noncoding genomic variant contributing to the etiology of a common human epilepsy via a posttranscriptional regulatory mechanism.

Management of developmental speech and language disorders: Part 1

The identification of developmental problems in a child's acquisition of speech, language and/or communication is a core activity in child surveillance. These are common difficulties with up to 15% of toddlers being 'late talkers' and 7% of children entering school with persisting impairments of their language development. These delays can confer disadvantages in the long term, adversely affecting language, cognition, academic attainment, behaviour and mental health. All children presenting with significant speech and language delay should be investigated with a comprehensive hearing assessment and be considered for speech and language therapy assessment. Socioeconomic adversity correlates with delayed language development. Clinical assessment should confirm that the presentation is definitely not acquired (see part 2) and will also guide whether the difficulty is primary, in which there are often familial patterns, or secondary, from a very wide range of aetiologies. Symptoms may be salient, such as the regression of communication in <3-year-olds which 'flags up' autism spectrum disorder. Further investigation will be informed from this clinical assessment, for example, genetic investigation for sex aneuploidies in enduring primary difficulties. Management of the speech and language difficulty itself is the realm of the speech and language therapist, who has an ever-increasing evidence-based choice of interventions. This should take place within a multidisciplinary team, particularly for children with more severe conditions who may benefit from individualised parental and educational supports.

When Is EEG Indicated in Attention-Deficit/Hyperactivity Disorder?

The authors investigated the parameters for predicting epileptiform abnormalities in a group of children diagnosed with attention-deficit/hyperactivity disorder (ADHD). The sample consisted of 148 subjects aged between 6 and 13 (8.76 ± 1.26; 25.7% female) years. Subtypes of ADHD and comorbid psychiatric disorders were defined according to DSM-IV criteria. The Wechsler Intelligence Scale for Children-Revised was applied to all patients. Most of the subjects (89.2%) had wakefulness and sleep electroencephalography examinations lasting about one hour. The authors found out that the coexistence of speech sound disorder (odds ratio [OR] 3.90, 95% confidence interval [CI]: 1.61-9.48) and higher Digit Span test performance (OR 1.24, 95% CI: 1.06-1.44) predicted the presence of accompanying epileptiform abnormalities. The prevalence of epileptiform abnormalities was 26.4%, and they were frequently localized in the frontal (41%) and centrotemporal (28.2%) regions. Higher percentage of speech sound disorder co-occurrence (64%) in subjects with rolandic spikes suggests that epileptiform abnormalities associated with ADHD can be determined genetically at least in some cases. Pathophysiology of epileptiform abnormalities in ADHD might have complex genetic and maturational background.

Pediatric epilepsy and comorbid reading disorders, math disorders, or autism spectrum disorders: Impact of epilepsy on cognitive patterns

INTRODUCTION

In pediatric epilepsy, comorbidities are reported to be frequent. The present study focusedon the cognitive patterns of children with isolated epilepsy, children with isolated neurodevelopmental disorders (reading disorders, math disorders, autism spectrum disorders), and children with epilepsy and these neurodevelopmental disorders as comorbidities.

METHODS

Based on two samples of referred children, one with epilepsy, reading disorders, math disorders, or ASDs occurring in "isolation" (n=117) and one with reading disorders, math disorders, and ASDs occurring comorbid with epilepsy (n=171), cognitive patterns were compared. The patterns displayed by verbal and nonverbal abilities from the WISC series were studied with repeated measures ANOVA. Thereafter, an exploratory 2∗3∗2 factorial analysis was done to study the independent contribution of the type of comorbidity and of the presence or absence of epilepsy to the VIQ-PIQ pattern.

RESULTS

In isolated epilepsy, a VIQ>PIQ pattern was found, which was not seen in the other disorders. When epilepsy and another disorder co-occurred, patterns were altered. They resembled partly the pattern seen in isolated epilepsy and partly the pattern seen in the isolated neurodevelopmental disorder. In comorbid reading disorders, the VIQ>PIQ pattern was mitigated; in comorbid math disorders, it was exacerbated. In comorbid ASDs, no clear pattern emerged. In the presence of epilepsy, patterns characteristic of isolated disorders appeared systematically shifted toward relatively lowered performance abilities or relatively spared verbal abilities. The similar "impact" exerted by epilepsy on the patterns of the various conditions suggested shared mechanisms.

Impaired performance on advanced Theory of Mind tasks in children with epilepsy is related to poor communication and increased attention problems

Children with epilepsy (CWE) have social difficulties that can persist into adulthood, and this could be related to problems with understanding others' thoughts, feelings, and intentions. This study assessed children's ability to interpret and reason on mental and emotional states (Theory of Mind) and examined the relationships between task scores and reports of communication and behavior. Performance of 56 CWE (8-16years of age) with below average IQ (n=17) or an average IQ (n=39) was compared with that of 62 healthy controls with an average IQ (6-16years of age) on cognition, language, and two advanced Theory of Mind (ToM) tasks that required children to attribute mental or emotional states to eye regions and to reason on internal mental states in order to explain behavior. The CWE-below average group were significantly poorer in both ToM tasks compared with controls. The CWE - average group showed a significantly poorer ability to reason on mental states in order to explain behavior, a difference that remained after accounting for lower IQ and language deficits. Poor ToM skills were related to increased communication and attention problems in both CWE groups. There is a risk for atypical social understanding in CWE, even for children with average cognitive function.

Insights into the genetic foundations of human communication

The human capacity to acquire sophisticated language is unmatched in the animal kingdom. Despite the discontinuity in communicative abilities between humans and other primates, language is built on ancient genetic foundations, which are being illuminated by comparative genomics. The genetic architecture of the language faculty is also being uncovered by research into neurodevelopmental disorders that disrupt the normally effortless process of language acquisition. In this article, we discuss the strategies that researchers are using to reveal genetic factors contributing to communicative abilities, and review progress in identifying the relevant genes and genetic variants. The first gene directly implicated in a speech and language disorder was FOXP2. Using this gene as a case study, we illustrate how evidence from genetics, molecular cell biology, animal models and human neuroimaging has converged to build a picture of the role of FOXP2 in neurodevelopment, providing a framework for future endeavors to bridge the gaps between genes, brains and behavior.

Cortical organization of language pathways in children with non-localized cryptogenic epilepsy

Children with a history of epilepsy are almost six times more likely than their unaffected siblings to be referred for speech or language therapy. However, the abnormalities in neural pathway that cause these delays are poorly understood. We recorded evoked fields using whole-head magnetoencephalography during real and non-word visual and auditory rhyme tasks in 15 children with non-localized cryptogenic epilepsy. Basic phonological and orthographic language skills were assessed using Woodcock–Johnson Test of Achievement subtests. Dynamic statistical parameter mapping was used with individual participant magnetic resonance images. Significant cortical activity was visualized on average and performance weighted maps. For the auditory rhyme tasks, bilateral primary and secondary auditory cortices, the superior temporal sulcus, and insular cortex were activated early with later increases in left hemisphere activity. Visual rhyme tasks evoked early bilateral primary and secondary occipital cortical and angular gyri activity followed by later activation of the planum temporale and supramarginal gyri and the left ventral occipitotemporal area. For the auditory rhyme tasks, performance weighted maps demonstrated that early right hemisphere activation was associated with poorer reading skills while later activity was associated with better reading skills; for the left hemisphere, greater early activation of the secondary auditory cortex, including the planum temporale, was related to better reading skills while relatively later activation of these areas was associated with poorer reading skills. For the visual rhyme tasks, greater activity in the bilateral ventral occipitotemporal and insular areas and angular and supramarginal gyri were associated with better performance. These data suggest that spatiotemporal cortical activation patterns are associated with variations in language performance in non-localized cryptogenic epilepsy.

DEPDC5 mutations in genetic focal epilepsies of childhood

Recent studies reported DEPDC5 loss-of-function mutations in different focal epilepsy syndromes. Here we identified 1 predicted truncation and 2 missense mutations in 3 children with rolandic epilepsy (3 of 207). In addition, we identified 3 families with unclassified focal childhood epilepsies carrying predicted truncating DEPDC5 mutations (3 of 82). The detected variants were all novel, inherited, and present in all tested affected (n=11) and in 7 unaffected family members, indicating low penetrance. Our findings extend the phenotypic spectrum associated with mutations in DEPDC5 and suggest that rolandic epilepsy, albeit rarely, and other nonlesional childhood epilepsies are among the associated syndromes.

The shape of the human language-ready brain

Our core hypothesis is that the emergence of our species-specific language-ready brain ought to be understood in light of the developmental changes expressed at the levels of brain morphology and neural connectivity that occurred in our species after the split from Neanderthals–Denisovans and that gave us a more globular braincase configuration. In addition to changes at the cortical level, we hypothesize that the anatomical shift that led to globularity also entailed significant changes at the subcortical level. We claim that the functional consequences of such changes must also be taken into account to gain a fuller understanding of our linguistic capacity. Here we focus on the thalamus, which we argue is central to language and human cognition, as it modulates fronto-parietal activity. With this new neurobiological perspective in place, we examine its possible molecular basis. We construct a candidate gene set whose members are involved in the development and connectivity of the thalamus, in the evolution of the human head, and are known to give rise to language-associated cognitive disorders. We submit that the new gene candidate set opens up new windows into our understanding of the genetic basis of our linguistic capacity. Thus, our hypothesis aims at generating new testing grounds concerning core aspects of language ontogeny and phylogeny.

RBFOX1 and RBFOX3 mutations in rolandic epilepsy

Partial deletions of the gene encoding the neuronal splicing regulator RBFOX1 have been reported in a range of neurodevelopmental diseases, including idiopathic generalized epilepsy. The RBFOX1 protein and its homologues (RBFOX2 and RBFOX3) regulate alternative splicing of many neuronal transcripts involved in the homeostatic control of neuronal excitability. In this study, we explored if structural microdeletions and exonic sequence variations in RBFOX1, RBFOX2, RBFOX3 confer susceptibility to rolandic epilepsy (RE), a common idiopathic focal childhood epilepsy. By high-density SNP array screening of 289 unrelated RE patients, we identified two hemizygous deletions, a 365 kb deletion affecting two untranslated 5′-terminal exons of RBFOX1 and a 43 kb deletion spanning exon 3 of RBFOX3. Exome sequencing of 242 RE patients revealed two novel probably deleterious variants in RBFOX1, a frameshift mutation (p.A233Vfs*74) and a hexanucleotide deletion (p.A299_A300del), and a novel nonsense mutation in RBFOX3 (p.Y287*). Although the three variants were inherited from unaffected parents, they were present in all family members exhibiting the RE trait clinically or electroencephalographically with only one exception. In contrast, no deleterious mutations of RBFOX1 and RBFOX3 were found in the exomes of 6503 non-RE subjects deposited in the Exome Variant Server database. The observed RBFOX3 exon 3 deletion and nonsense mutation suggest that RBFOX3 represents a novel risk factor for RE, indicating that exon deletions and truncating mutations of RBFOX1 and RBFOX3 contribute to the genetic variance of partial and generalized idiopathic epilepsy syndromes.

Genetic insights into the functional elements of language

Language disorders cover a wide range of conditions with heterologous and overlapping phenotypes and complex etiologies harboring both genetic and environmental influences. Genetic approaches including the identification of genes linked to speech and language phenotypes and the characterization of normal and aberrant functions of these genes have, in recent years, unraveled complex details of molecular and cognitive mechanisms and provided valuable insight into the biological foundations of language. Consistent with this approach, we have reviewed the functional aspects of allelic variants of genes which are currently known to be either causally associated with disorders of speech and language or impact upon the spectrum of normal language ability. We have also reviewed candidate genes associated with heritable speech and language disorders. In addition, we have evaluated language phenotypes and associated genetic components in developmental syndromes that, together with a spectrum of altered language abilities, manifest various phenotypes and offer details of multifactorial determinants of language function. Data from this review have revealed a predominance of regulatory networks involved in the control of differentiation and functioning of neurons, neuronal tracks and connections among brain structures associated with both cognitive and language faculties. Our findings, furthermore, have highlighted several multifactorial determinants in overlapping speech and language phenotypes. Collectively this analysis has revealed an interconnected developmental network and a close association of the language faculty with cognitive functions, a finding that has the potential to provide insight into linguistic hypotheses defining in particular, the contribution of genetic elements to and the modular nature of the language faculty.

Fluency patterns in narratives from children with localization related epilepsy

This study assessed the relationship between fluency and language demand in children with epilepsy, a group known to demonstrate depressed language skills. Disfluency type and frequencies were analyzed in elicited narratives from 52 children. Half of these children had localization-related epilepsy (CWE), while the others were age- and gender-matched typically-developing (TD) peers. CWE were found to be significantly more disfluent overall than their matched TD peers during narrative productions, and demonstrated a higher proportion of stutter-like disfluencies, particularly prolongations. The current study adds to an emerging literature that has found depressed language skills and listener perceptions of verbal ability in children with chronic seizure activity, and contributes to the small but growing literature that suggests that disfluency during spoken language tasks may be a subtle marker of expressive language impairment.

EDUCATIONAL OBJECTIVES

The reader will be able to (a) describe why children with epilepsy might be at greater risk for language delays and or increased levels of disfluency; (b) describe profiles of fluency that differentiated children with chronic and recent-onset epilepsy from their age and gender matched peers; and (c) apply this information to monitoring of children with seizure disorder on their caseloads.

Neurogenomics of speech and language disorders: the road ahead

Next-generation sequencing is set to transform the discovery of genes underlying neurodevelopmental disorders, and so offer important insights into the biological bases of spoken language. Success will depend on functional assessments in neuronal cell lines, animal models and humans themselves.

Narrative abilities of children with epilepsy

BACKGROUND

There is a noticeable publication gap in the speech-language pathology literature regarding the language abilities of children with common types of epilepsy. This paper reviews studies that suggest a high frequency of undetected language problems in this population, and it proposes the need for pragmatically based assessment of children with epilepsy that includes analysis of spontaneous language skills.

AIMS

To compare the language skills of two groups of children with epilepsy-those with recent onset seizures and those with more chronic seizure activity (>3 years' duration)-using a mix of standardized tests, analysis of elicited narratives and listener judgments of the children's narratives.

METHODS & PROCEDURES

Twenty-five children with epilepsy, divided into two groups (recent onset versus chronic), were age- and gender-matched to 25 typically functioning peers. In addition to standardized IQ and language testing, children produced narratives to accompany the book Frog, Where Are You? (1969). Narratives were analysed for syntax, vocabulary and narrative components. Forty-five adult listeners each blindly rated nine narratives to create a large pool of listener judgments.

OUTCOMES & RESULTS

Children with chronic epilepsy showed the greatest and significant differences in both language skill and listener judgments from their unaffected peers. Differences were smaller for children whose epilepsy was of more recent onset and their matched peers.

CONCLUSIONS & IMPLICATIONS

Although based on cross-sectional data rather than on longitudinal study, the current results raise the possibility that continued seizures, or prolonged exposure to the medications used to control them, produce decrements in children's language performance over time. Thus, the authors strongly urge that there is greater awareness of seizure disorder among speech-and-language pathologists/therapists, and they strongly recommend baseline testing at first diagnosis so that changes over time can be reliably documented.

Is lower IQ in children with epilepsy due to lower parental IQ? A controlled comparison study

AIM

The aim of this study was to determine the relationship between parent and child Full-scale IQ (FSIQ) in children with epilepsy and in typically developing comparison children and to examine parent-child IQ differences by epilepsy characteristics.

METHOD

The study participants were 97 children (50 males, 47 females; age range 8-18y; mean age 12y 3mo, SD 3y1mo) with recent-onset epilepsy including idiopathic generalized (n=43) and idiopathic localization-related epilepsies (n=54); 69 healthy comparison children (38 females, 31 males; age range 8-18y; mean age 12y 8mo, SD 3y 2mo), and one biological parent per child. All participants were administered the Wechsler Abbreviated Scale of Intelligence (WASI). FSIQ was compared in children with epilepsy and typically developing children; FSIQ was compared in the parents of typically developing children and the parents of participants with epilepsy; parent-child FSIQ differences were compared between the groups.

RESULTS

FSIQ was lower in children with epilepsy than in comparison children (p<0.001). FSIQ of parents of children with epilepsy did not differ from the FSIQ of the parents of typically developing children. Children with epilepsy had significantly lower FSIQ than their parents (p<0.001), whereas comparison children did not. The parent-child IQ difference was significantly higher in the group with epilepsy than the comparison group (p=0.043). Epilepsy characteristics were not related to parent-child IQ difference.

INTERPRETATION

Parent-child IQ difference appears to be a marker of epilepsy impact independent of familial IQ, epilepsy syndrome, and clinical seizure features. This marker is evident early in the course of idiopathic epilepsies and can be tracked over time.

Association of language dysfunction and age of onset of benign epilepsy with centrotemporal spikes in children

BACKGROUND

Language dysfunction in children with benign epilepsy with centrotemporal spikes (BECTS) has been well recognized but data regarding its risk factors are heterogenous.

AIMS

To assess language function in children with BECTS and its association with the age of epilepsy onset.

METHODS

We assessed language function in 61 children with BECTS and 35 age and sex-matched controls. Children with BECTS performed significantly worse on all language tasks as compared to controls and overall better language function was positively correlated with older age of the child. Early age at seizure onset demonstrated significant negative correlation with language dysfunction, age below 6 years being related to the lowest performance scores. There was no relationship between the language function and the laterality of epileptic focus, seizure treatment status, or the duration of epilepsy.

CONCLUSION

Children with BECTS have language difficulties that are more pronounced in younger age group. Despite better language functioning in older children with BECTS, their verbal abilities remain inferior to those of children without epilepsy. Early age at seizure onset is a significant factor predicting worse language functioning in children with BECTS.

The genetics of reading disability in an often excluded sample: novel loci suggested for reading disability in Rolandic epilepsy

BACKGROUND

Reading disability (RD) is a common neurodevelopmental disorder with genetic basis established in families segregating "pure" dyslexia. RD commonly occurs in neurodevelopmental disorders including Rolandic Epilepsy (RE), a complex genetic disorder. We performed genomewide linkage analysis of RD in RE families, testing the hypotheses that RD in RE families is genetically heterogenenous to pure dyslexia, and shares genetic influences with other sub-phenotypes of RE.

METHODS

We initially performed genome-wide linkage analysis using 1000 STR markers in 38 US families ascertained through a RE proband; most of these families were multiplex for RD. We analyzed the data by two-point and multipoint parametric LOD score methods. We then confirmed the linkage evidence in a second US dataset of 20 RE families. We also resequenced the SEMA3C gene at the 7q21 linkage locus in members of one multiplex RE/RD pedigree and the DISC1 gene in affected pedigrees at the 1q42 locus.

RESULTS

In the discovery dataset there was suggestive evidence of linkage for RD to chromosome 7q21 (two-point LOD score 3.05, multipoint LOD 3.08) and at 1q42 (two-point LOD 2.87, multipoint LOD 3.03). Much of the linkage evidence at 7q21 derived from families of French-Canadian origin, whereas the linkage evidence at 1q42 was well distributed across all the families. There was little evidence for linkage at known dyslexia loci. Combining the discovery and confirmation datasets increased the evidence at 1q42 (two-point LOD = 3.49, multipoint HLOD = 4.70), but decreased evidence at 7q21 (two-point LOD = 2.28, multipoint HLOD  = 1.81), possibly because the replication sample did not have French Canadian representation.

DISCUSSION

Reading disability in rolandic epilepsy has a genetic basis and may be influenced by loci at 1q42 and, in some populations, at 7q21; there is little evidence of a role for known DYX loci discovered in "pure" dyslexia pedigrees. 1q42 and 7q21 are candidate novel dyslexia loci.