Executive Dysfunction in Female FMR1 Premutation Carriers

Insight and Recommendations for Fragile X-Premutation-Associated Conditions from the Fifth International Conference on FMR1 Premutation

The premutation of the fragile X messenger ribonucleoprotein 1 (FMR1) gene is characterized by an expansion of the CGG trinucleotide repeats (55 to 200 CGGs) in the 5' untranslated region and increased levels of FMR1 mRNA. Molecular mechanisms leading to fragile X-premutation-associated conditions (FXPAC) include cotranscriptional R-loop formations, FMR1 mRNA toxicity through both RNA gelation into nuclear foci and sequestration of various CGG-repeat-binding proteins, and the repeat-associated non-AUG (RAN)-initiated translation of potentially toxic proteins. Such molecular mechanisms contribute to subsequent consequences, including mitochondrial dysfunction and neuronal death. Clinically, premutation carriers may exhibit a wide range of symptoms and phenotypes. Any of the problems associated with the premutation can appropriately be called FXPAC. Fragile X-associated tremor/ataxia syndrome (FXTAS), fragile X-associated primary ovarian insufficiency (FXPOI), and fragile X-associated neuropsychiatric disorders (FXAND) can fall under FXPAC. Understanding the molecular and clinical aspects of the premutation of the FMR1 gene is crucial for the accurate diagnosis, genetic counseling, and appropriate management of affected individuals and families. This paper summarizes all the known problems associated with the premutation and documents the presentations and discussions that occurred at the International Premutation Conference, which took place in New Zealand in 2023.

Executive Function and Working Memory Deficits in Females with Fragile X Premutation

The Fragile X premutation is a genetic instability of the FMR1 gene caused by 55–199 recurrences of the CGG sequence, whereas there are only 7–54 repeats of the CGG sequence in the normal condition. While males with the premutation of Fragile X were found to have difficulties in executive functions and working memory, little data have been collected on females. This study is among the first to address executive functions and phonological memory in females with the Fragile X premutation. Twenty-three female carriers aged 20–55 years and twelve non carrier females matched in age and levels of education (in years) participated in this study. Executive functions and phonological memory were assessed using the self-report questionnaire The Behavior Rating Inventory of Executive Function (BRIEF) and behavioral measures (nonword repetitions, forward and backward digit span). Females who were carriers of the premutation of the FMR1 gene reported less efficient executive functions in the BRIEF questionnaire compared to the control group. In addition, a relationship was found between the number of repetitions on the CGG sequence of nucleotides, nonword repetitions, and forward digit span. The findings suggest that the premutation of Fragile X in females affects their performance of executive functions and may have impact on everyday functioning.

FMR1 CGG Repeats and Stress Influence Self-Reported Cognitive Functioning in Mothers

Variation in the FMR1 gene may affect aspects of cognition, such as executive function and memory. Environmental factors, such as stress, may also negatively impact cognitive functioning. Participants included 1,053 mothers of children with and without developmental disabilities. Participants completed self-report measures of executive function, memory, and stress (i.e., life events, parenting status), and provided DNA to determine CGG repeat length (ranging from 7 to 192 CGGs). Stress exposure significantly predicted greater self-reported difficulties in executive function and the likelihood of memory problems. Cubic CGG effects independently predicted executive function and memory difficulties, suggesting effects of both genetic variation and environmental stress exposure on cognitive functioning.

Verbal inhibition declines among older women with high FMR1 premutation expansions: A prospective study

The FMR1 premutation has been associated with difficulties in executive functioning, including verbal inhibition. However, little is known about the longitudinal profiles of verbal inhibition among FMR1 premutation carriers, particularly in women, and how individual factors such as aging and CGG repeat length may contribute to changes in verbal inhibition over time. The present study examined verbal inhibition performance (i.e., inhibition errors) on the Hayling Sentence Completion Task in a cohort of 92 women with the FMR1 premutation across two timepoints approximately three years apart. We examined the effects of age, CGG repeat length, and their interactions on verbal inhibition over time. We also evaluated whether response latency affected verbal inhibition errors. We found no significant change in verbal inhibition in the full cohort during the three-year study period. However, a subset of FMR1 premutation carriers, namely older participants with higher CGG repeats, evidenced greater declines in verbal inhibition over time. Longer response latencies did not compensate for verbal inhibition errors. The findings suggest that a subset of women with the FMR1 premutation may be at earlier, increased risk for changes in executive functioning, which if confirmed, should be considered as part of the clinical profile associated with the premutation.

Maternal Pragmatic Language Difficulties in the FMR1 Premutation and the Broad Autism Phenotype: Associations with Individual and Family Outcomes

Broader phenotypes associated with genetic liability, including mild difficulties with pragmatic language skills, have been documented in mothers of children with autism spectrum disorder (ASD) and mothers of children with fragile X syndrome (FXS). This study investigated the relationship between pragmatic difficulties and indicators of maternal well-being and family functioning. Pragmatic difficulty was associated with loneliness in mothers of children with ASD or FXS, and with depression, decreased life satisfaction, and poorer family relationship quality in mothers of children with FXS only. Results inform subtle maternal pragmatic language difficulties as a risk factor that that may contribute to reduced health and well-being, informing tailored support services to better meet the unique needs of families of children with ASD or FXS.

Family history of FXTAS is associated with age-related cognitive-linguistic decline among mothers with the FMR1 premutation

BACKGROUND

Women who carry a premutation allele of the FMR1 gene are at increased vulnerability to an array of age-related symptoms and disorders, including age-related decline in select cognitive skills. However, the risk factors for age-related decline are poorly understood, including the potential role of family history and genetic factors. In other forms of pathological aging, early decline in syntactic complexity is observed and predicts the later onset of neurodegenerative disease. To shed light on the earliest signs of degeneration, the present study characterized longitudinal changes in the syntactic complexity of women with the FMR1 premutation across midlife, and associations with family history of fragile X-associated tremor/ataxia syndrome (FXTAS) and CGG repeat length.

METHODS

Forty-five women with the FMR1 premutation aged 35-64 years at study entry participated in 1-5 longitudinal assessments spaced approximately a year apart (130 observations total). All participants were mothers of children with confirmed fragile X syndrome. Language samples were analyzed for syntactic complexity and participants provided information on family history of FXTAS. CGG repeat length was determined via molecular genetic testing.

RESULTS

Hierarchical linear models indicated that women who reported a family history of FXTAS exhibited faster age-related decline in syntactic complexity than those without a family history, with that difference emerging as the women reached their mid-50 s. CGG repeat length was not a significant predictor of age-related change.

CONCLUSIONS

Results suggest that women with the FMR1 premutation who have a family history of FXTAS may be at increased risk for neurodegenerative disease, as indicated by age-related loss of syntactic complexity. Thus, family history of FXTAS may represent a personalized risk factor for age-related disease. Follow-up study is needed to determine whether syntactic decline is an early indicator of FXTAS specifically, as opposed to being a more general age-related cognitive decline associated with the FMR1 premutation.

Evidence for Three Subgroups of Female FMR1 Premutation Carriers Defined by Distinct Neuropsychiatric Features: A Pilot Study

Over 200 Cytosine-guanine-guanine (CGG) trinucleotide repeats in the 5' untranslated region of the Fragile X mental retardation 1 (FMR1) gene results in a "full mutation," clinically Fragile X Syndrome (FXS), whereas 55 - 200 repeats result in a "premutation." FMR1 premutation carriers (PMC) are at an increased risk for a range of psychiatric, neurocognitive, and physical conditions. Few studies have examined the variable expression of neuropsychiatric features in female PMCs, and whether heterogeneous presentation among female PMCs may reflect differential presentation of features in unique subgroups. In the current pilot study, we examined 41 female PMCs (ages 17-78 years) and 15 age-, sex-, and IQ-matched typically developing controls (TDC) across a battery of self-report, eye tracking, expressive language, neurocognitive, and resting state EEG measures to determine the feasibility of identifying discrete clusters. Secondly, we sought to identify the key features that distinguished these clusters of female PMCs. We found a three cluster solution using k-means clustering. Cluster 1 represented a psychiatric feature group (27% of our sample); cluster 2 represented a group with executive dysfunction and elevated high frequency neural oscillatory activity (32%); and cluster 3 represented a relatively unaffected group (41%). Our findings indicate the feasibility of using a data-driven approach to identify naturally occurring clusters in female PMCs using a multi-method assessment battery. CGG repeat count and its association with neuropsychiatric features differ across clusters. Together, our findings provide important insight into potential diverging pathophysiological mechanisms and risk factors for each female PMC cluster, which may ultimately help provide novel and individualized targets for treatment options.

The Phenotypic Profile Associated With the FMR1 Premutation in Women: An Investigation of Clinical-Behavioral, Social-Cognitive, and Executive Abilities

The FMR1 gene in its premutation (PM) state has been linked to a range of clinical and subclinical phenotypes among FMR1 PM carriers, including some subclinical traits associated with autism spectrum disorder (ASD). This study attempted to further characterize the phenotypic profile associated with the FMR1 PM by studying a battery of assessments examining clinical-behavioral traits, social-cognitive, and executive abilities in women carrying the FMR1 PM, and associations with FMR1-related variability. Participants included 152 female FMR1 PM carriers and 75 female controls who were similar in age and IQ, and screened for neuromotor impairments or signs of fragile X-associated tremor/ataxia syndrome. The phenotypic battery included assessments of ASD-related personality and language (i.e., pragmatic) traits, symptoms of anxiety and depression, four different social-cognitive tasks that tapped the ability to read internal states and emotions based on different cues (e.g., facial expressions, biological motion, and complex social scenes), and a measure of executive function. Results revealed a complex phenotypic profile among the PM carrier group, where subtle differences were observed in pragmatic language, executive function, and social-cognitive tasks that involved evaluating basic emotions and trustworthiness. The PM carrier group also showed elevated rates of ASD-related personality traits. In contrast, PM carriers performed similarly to controls on social-cognitive tasks that involved reliance on faces and biological motion. The PM group did not differ from controls on self-reported depression or anxiety symptoms. Using latent profile analysis, we observed three distinct subgroups of PM carriers who varied considerably in their performance across tasks. Among PM carriers, CGG repeat length was a significant predictor of pragmatic language violations. Results suggest a nuanced phenotypic profile characterized by subtle differences in select clinical-behavioral, social-cognitive, and executive abilities associated with the FMR1 PM in women.

Family as a Context for Child Development: Mothers with the FMR1 Premutation and Their Children with Fragile X Syndrome

Fragile X syndrome (FXS) is a genetic disorder caused by changes of the FMR1 gene that is passed along among families. A range of developmental processes may be impacted with wide variation in abilities across individuals with FXS. Mothers of children with FXS are often carriers of a "premutation" expansion on the FMR1 gene, which is associated with its own clinical phenotype. These maternal features may increase individual and family vulnerabilities, including increased risk for depression and anxiety disorders and difficulties in social and cognitive ability. These characteristics may worsen with age, and potentially interact with a child's challenging behaviors and with family dynamics. Thus, families of children with FXS may experience unique challenges related to genetic risk, manifested across both children and parents, that should be considered in therapeutic planning to optimize outcomes for children and their families. In this article, we review core features of the FMR1 premutation as expressed in mothers and aspects of the family environment that interface with developmental outcomes of children with FXS. Recommendations for family-centered support services are discussed.

Mild Neurological Signs in FMR1 Premutation Women in an Unselected Community-Based Cohort

BACKGROUND

Premutation-sized (55-200) CGG repeat expansions in the FMR1 gene cause fragile X-associated tremor/ataxia syndrome (FXTAS). Most studies of premutation carriers utilized reverse ascertainment to identify patients, leading to a selection bias for larger repeats. As shorter CGG premutation repeats are common in the population, understanding their impact on health outcomes has a potentially large public health footprint.

OBJECTIVE

The study's objective was to compare an unselected group of premutation carriers (n = 35, 55-101 CGG repeats) with matched controls (n = 61, 29-39 CGG repeats) with respect to FXTAS-type signs using structured neurological assessments.

METHODS

Three neurologists independently rated signs, using an adapted version of the FXTAS Rating Scale (Leehey MA, Berry-Kravis E, Goetz CG, et al. FMR1 CGG repeat length predicts motor dysfunction in premutation carriers. Neurology. 2008). This was a double-blind study, as genetic status (premutation vs. control) was known neither by the participants nor by any of the neurologists. Analyses controlled potentially confounding comorbid conditions in the electronic health record (eg, osteoarthritis and stroke) and probed the association of age with signs.

RESULTS

Although there was no overall difference between carriers and controls, among individuals without any potentially confounding comorbid diagnoses, there was a statistically significant age-associated elevation in FXTAS-type signs in premutation carriers compared to controls.

CONCLUSIONS

Among those who do not have other comorbid diagnoses, women who have CGG repeats at the lower end of the premutation range may be at greater risk for ataxia and parkinsonism than their age peers, although their overall risk of developing such clinical features is low. This study should provide reassurance to those who share characteristics with the present cohort. © 2021 International Parkinson and Movement Disorder Society.

Relationships between motor scores and cognitive functioning in FMR1 female premutation X carriers indicate early involvement of cerebello-cerebral pathways

BACKGROUND

Smaller expansions of CGG trinucleotide repeats in the FMR1 X-linked gene termed 'premutation' lead to a neurodegenerative disorder: Fragile X Associated Tremor/Ataxia Syndrome (FXTAS) in nearly half of aged carrier males, and 8-16% females. Core features include intention tremor, ataxia, and cognitive decline, and white matter lesions especially in cerebellar and periventricular locations. A 'toxic' role of elevated and expanded FMR1 mRNA has been linked to the pathogenesis of this disorder. The emerging issue concerns the trajectory of the neurodegenerative changes: is the pathogenetic effect confined to overt clinical manifestations? Here we explore the relationships between motor and cognitive scale scores in a sample of 57 asymptomatic adult female premutation carriers of broad age range.

METHODS

Three motor scale scores (ICARS-for tremor/ataxia, UPDRS-for parkinsonism, and Clinical Tremor) were related to 11 cognitive tests using Spearman's rank correlations. Robust regression, applied in relationships between all phenotypic measures, and genetic molecular and demographic data, identified age and educational levels as common correlates of these measures, which were then incorporated as confounders in correlation analysis.

RESULTS

Cognitive tests demonstrating significant correlations with motor scores were those assessing non-verbal reasoning on Matrix Reasoning (p-values from 0.006 to 0.011), and sequencing and alteration on Trails-B (p-values from 0.008 to 0.001). Those showing significant correlations with two motor scores-ICARS and Clinical Tremor- were psychomotor speed on Symbol Digit Modalities (p-values from 0.014 to 0.02) and working memory on Digit Span Backwards (p-values from 0.024 to 0.011).

CONCLUSIONS

Subtle motor impairments correlating with cognitive, particularly executive, deficits may occur in female premutation carriers not meeting diagnostic criteria for FXTAS. This pattern of cognitive deficits is consistent with those seen in other cerebellar disorders. Our results provide evidence that more than one category of clinical manifestation reflecting cerebellar changes - motor and cognitive - may be simultaneously affected by premutation carriage across a broad age range in asymptomatic carriers.

A Unique Visual Attention Profile Associated With the FMR1 Premutation

Atypical visual attention patterns have been observed among carriers of the fragile X mental retardation gene (FMR1) premutation (PM), with some similarities to visual attention patterns observed in autism spectrum disorder (ASD) and among clinically unaffected relatives of individuals with ASD. Patterns of visual attention could constitute biomarkers that can help to inform the neurocognitive profile of the PM, and that potentially span diagnostic boundaries. This study examined patterns of eye movement across an array of fixation measurements from three distinct eye-tracking tasks in order to investigate potentially overlapping profiles of visual attention among PM carriers, ASD parents, and parent controls. Logistic regression analyses were conducted to examine whether variables constituting a PM-specific looking profile were able to effectively predict group membership. Participants included 65PM female carriers, 188 ASD parents, and 84 parent controls. Analyses of fixations across the eye-tracking tasks, and their corresponding areas of interest, revealed a distinct visual attention pattern in carriers of the FMR1 PM, characterized by increased fixations on the mouth when viewing faces, more intense focus on bodies in socially complex scenes, and decreased fixations on salient characters and faces while narrating a wordless picture book. This set of variables was able to successfully differentiate individuals with the PM from controls (Sensitivity = 0.76, Specificity = 0.85, Accuracy = 0.77) as well as from ASD parents (Sensitivity = 0.70, Specificity = 0.80, Accuracy = 0.72), but did not show a strong distinction between ASD parents and controls (Accuracy = 0.62), indicating that this set of variables comprises a profile that is unique to PM carriers. Regarding predictive power, fixations toward the mouth when viewing faces was able to differentiate PM carriers from both ASD parents and controls, whereas fixations toward other social stimuli did not differentiate PM carriers from ASD parents, highlighting some overlap in visual attention patterns that could point toward shared neurobiological mechanisms. Results demonstrate a profile of visual attention that appears strongly associated with the FMR1 PM in women, and may constitute a meaningful biomarker.

Differential Progression of Motor Dysfunction Between Male and Female Fragile X Premutation Carriers Reveals Novel Aspects of Sex-Specific Neural Involvement

Expansions of the CGG repeat in the non-coding segment of the FMR1 X-linked gene are associated with a variety of phenotypic changes. Large expansions (>200 repeats), which cause a severe neurodevelopmental disorder, the fragile x syndrome (FXS), are transmitted from the mothers carrying smaller, unstable expansions ranging from 55 to 200 repeats, termed the fragile X premutation. Female carriers of this premutation may themselves experience a wide range of clinical problems throughout their lifespan, the most severe being the late onset neurodegenerative condition called "Fragile X-Associated Tremor Ataxia Syndrome" (FXTAS), occurring between 8 and 16% of these carriers. Male premutation carriers, although they do not transmit expanded alleles to their daughters, have a much higher risk (40-50%) of developing FXTAS. Although this disorder is more prevalent and severe in male than female carriers, specific sex differences in clinical manifestations and progress of the FXTAS spectrum have been poorly documented. Here we compare the pattern and rate of progression (per year) in three motor scales including tremor/ataxia (ICARS), tremor (Clinical Tremor Rating scale, CRST), and parkinsonism (UPDRS), and in several cognitive and psychiatric tests scores, between 13 female and 9 male carriers initially having at least one of the motor scores ≥10. Moreover, we document the differences in each of the clinical and cognitive measures between the cross-sectional samples of 21 female and 24 male premutation carriers of comparable ages with FXTAS spectrum disorder (FSD), that is, who manifest one or more features of FXTAS. The results of progression assessment showed that it was more than twice the rate in male than in female carriers for the ICARS-both gait ataxia and kinetic tremor domains and twice as high in males on the CRST scale. In contrast, sex difference was negligible for the rate of progress in UPDRS, and all the cognitive measures. The overall psychiatric pathology score (SCL-90), as well as Anxiety and Obsessive/Compulsive domain scores, showed a significant increase only in the female sample. The pattern of sex differences for progression in motor scores was consistent with the results of comparison between larger, cross-sectional samples of male and female carriers affected with the FSD. These results were in concert with sex-specific distribution of MRI T2 white matter hyperintensities: all males, but no females, showed the middle cerebellar peduncle white matter hyperintensities (MCP sign), although the distribution and severity of these hyperintensities in the other brain regions were not dissimilar between the two sexes. In conclusion, the magnitude and specific pattern of sex differences in manifestations and progression of clinically recorded changes in motor performance and MRI lesion distribution support, on clinical grounds, the possibility of certain sex-limited factor(s) which, beyond the predictable effect of the second, normal FMR1 alleles in female premutation carriers, may have neuroprotective effects, specifically concerning the cerebellar circuitry.

Delineating the Relationships Between Motor, Cognitive-Executive and Psychiatric Symptoms in Female FMR1 Premutation Carriers

Introduction: Premutation expansions (55-200 CGG repeats) of the Fragile X Mental Retardation 1 (FMR1) gene on the X chromosome are associated with a range of clinical features. Apart from the most severe - Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) - where the most typical white matter changes affect cerebellar peduncles, more subtle changes may include impairment of executive functioning, affective disorders and/or subtle motor changes. Here we aimed to examine whether performance in selected components of executive functioning is associated with subclinical psychiatric symptoms in non-FXTAS, adult females carrying the FMR1 premutation. Methods and Sample: A total of 47 female premutation carriers (sub-symptomatic for FXTAS) of wide age range (26-77 years; M = 50.3; SD = 10.9) were assessed using standard neuropsychological tests, three motor rating scales and self-reported measures of psychiatric symptoms using the Symptom Checklist-90-Revised (SCL-90-R). Results: After adjusting for age and educational level where appropriate, both non-verbal reasoning and response inhibition as assessed on the Stroop task (i.e., the ability to resolve cognitive interference) were associated with a range of primary psychiatric symptom dimensions, and response inhibition uniquely predicted some primary symptoms and global psychiatric features. Importantly, lower scores (worse performance) in response inhibition were also strongly correlated with higher (worse) scores on standard motor rating scales for tremor-ataxia and for parkinsonism. Conclusion: These results provide evidence for the importance of response inhibition in the manifestation of psychiatric symptoms and subtle tremor-ataxia motor features, suggestive of the presence of early cerebellar changes in female premutation carriers.

Response Inhibition Deficits in Women with the FMR1 Premutation are Associated with Age and Fall Risk

One in 113-178 females worldwide carry a premutation allele on the FMR1 gene. The FMR1 premutation is linked to neurocognitive and neuromotor impairments, although the phenotype is not fully understood, particularly with respect to age effects. This study sought to define oculomotor response inhibition skills in women with the FMR1 premutation and their association with age and fall risk. We employed an antisaccade eye-tracking paradigm to index oculomotor inhibition skills in 35 women with the FMR1 premutation and 28 control women. The FMR1 premutation group exhibited longer antisaccade latency and reduced accuracy relative to controls, indicating deficient response inhibition skills. Longer response latency was associated with older age in the FMR1 premutation and was also predictive of fall risk. Findings highlight the utility of the antisaccade paradigm for detecting early signs of age-related executive decline in the FMR1 premutation, which is related to fall risk. Findings support the need for clinical prevention efforts to decrease and delay the trajectory of age-related executive decline in women with the FMR1 premutation during midlife.

Borderline intellectual functioning

Borderline intellectual functioning (BIF), that is to say, tested IQ levels in the range of 70-84/85, is prevalent, affecting about 12%-14% of the population depending on the exact level for "diagnostic" cutoff. In the current Diagnostic and Statistical Manual of Mental Disorders, BIF does not have a separate diagnostic category but can be categorized with a V-code. Children and adolescents with BIF usually struggle both as regards school performance and in respect of social functioning. BIF is common in attention deficit hyperactivity disorder, but sometimes attention problems in schoolchildren with BIF may be a consequence of nonadapted academic demands. Autism and BIF may also coexist, and there are many cases of so-called high-functioning autism who are high functioning only in the sense that they do not meet criteria for intellectual disability, but function in the area of BIF. Currently, too little attention is given to the negative effects of BIF on child development and adaptation. Learning, academic, and behavioral problems and grade retention may be markers of BIF. Our diagnostic and classification manuals need to have specific categories that clarify the problems that BIF entails so that affected individuals can avail themselves of better educational support and understanding.

Inhibition deficits are modulated by age and CGG repeat length in carriers of the FMR1 premutation allele who are mothers of children with fragile X syndrome

Individuals who carry a premutation (PM) allele on the FMR1 gene may experience executive limitations associated with their genetic status, including inhibition deficits. However, poor understanding of individualized risk factors has limited clinical management of this group, particularly in mothers who carry the PM allele who have children with fragile X syndrome (FXS). The present study examined CGG repeat length and age as factors that may account for variable expressivity of inhibition deficits. Participants were 134 carriers of the PM allele who were mothers of children with FXS. Inhibition skills were measured using both self-report and direct behavioral assessments. Increased vulnerability for inhibition deficits was observed at mid-range CGG lengths of approximately 80-100 repeats, with some evidence of a second zone of vulnerability occurring at approximately 130-140 CGG repeats. Risk associated with the genotype also became more pronounced with older age. This study identifies personalized risk factors that may be used to tailor the clinical management of executive deficits in carriers of the PM allele. Inhibition deficits may contribute to poor outcomes in carriers of the PM allele and their families, particularly in midlife and early old age, and clinical monitoring may be warranted.

Language processing skills linked to FMR1 variation: A study of gaze-language coordination during rapid automatized naming among women with the FMR1 premutation

The FMR1 premutation (PM) is relatively common in the general population. Evidence suggests that PM carriers may exhibit subtle differences in specific cognitive and language abilities. This study examined potential mechanisms underlying such differences through the study of gaze and language coordination during a language processing task (rapid automatized naming; RAN) among female carriers of the FMR1 PM. RAN taps a complex set of underlying neuropsychological mechanisms, with breakdowns implicating processing disruptions in fundamental skills that support higher order language and executive functions, making RAN (and analysis of gaze/language coordination during RAN) a potentially powerful paradigm for revealing the phenotypic expression of the FMR1 PM. Forty-eight PM carriers and 56 controls completed RAN on an eye tracker, where they serially named arrays of numbers, letters, colors, and objects. Findings revealed a pattern of inefficient language processing in the PM group, including a greater number of eye fixations (namely, visual regressions) and reduced eye-voice span (i.e., the eyes' lead over the voice) relative to controls. Differences were driven by performance in the latter half of the RAN arrays, when working memory and processing load are the greatest, implicating executive skills. RAN deficits were associated with broader social-communicative difficulties among PM carriers, and with FMR1-related molecular genetic variation (higher CGG repeat length, lower activation ratio, and increased levels of the fragile X mental retardation protein; FMRP). Findings contribute to an understanding of the neurocognitive profile of PM carriers and indicate specific gene-behavior associations that implicate the role of the FMR1 gene in language-related processes.

Altered sensitivity to social gaze in the FMR1 premutation and pragmatic language competence

Background

The FMR1 premutation affects 1:291 women and is associated with a range of cognitive, affective, and physical health complications, including deficits in pragmatic language (i.e., social language). This study investigated attention to eye gaze as a fundamental social-cognitive skill that may be impaired in the FMR1 premutation and could underlie pragmatic deficits. Given the high prevalence of the FMR1 premutation, efforts to define its phenotype and mechanistic underpinnings have significant public health implications.

Methods

Thirty-five women with the FMR1 premutation and 20 control women completed an eye-tracking paradigm that recorded time spent dwelling within the eye region in response to a face displaying either direct or averted gaze. Pragmatic language ability was coded from a conversational sample using the Pragmatic Rating Scale.

Results

Women with the FMR1 premutation failed to show attentional preference to direct gaze and spent more time dwelling on the averted eyes relative to controls. While dwelling on the eyes was associated with better pragmatic language performance in controls, these variables were unrelated in the women with the FMR1 premutation.

Conclusions

Altered sensitivity to social gaze, characterized by increased salience of averted gaze, was observed among women with the FMR1 premutation. Furthermore, women with the FMR1 premutation were unable to capitalize on information conveyed through the eyes to enhance social-communicative engagement, which differed from patterns seen in controls. These findings contribute to the growing characterization of social and communication phenotypes associated with the FMR1 premutation.

Long term verbal memory recall deficits in fragile X premutation females

Carriers of a FMR1 premutation allele (between 55 and 199 CGG repeats) are at risk of developing a wide range of medical, psychiatric and cognitive disorders, including executive dysfunction. These cognitive deficits are often less severe for female premutation carriers compared to male premutation carriers, albeit similar in nature. However, it remains unclear whether female premutation carriers who exhibit executive dysfunction also report verbal learning and memory deficits like those of their male counterparts. Here we employed the CVLT to assess verbal learning and memory function in 19 female premutation carriers, contrasting performance with 19 age- and IQ-matched controls. Group comparisons revealed similar performance during the learning and short delay recall phases of the CVLT. However, after a long delay period, female premutation carriers remembered fewer words for both free and cued recall trials, but not during recognition trials. These findings are consistent with reports for male premutation carriers, and suggest that aspects of long term memory may be adversely affect in a subgroup of premutation carriers with signs of executive dysfunction.

White matter microstructure, cognition, and molecular markers in fragile X premutation females

Objective:

To examine the interrelationships between fragile X mental retardation 1 (FMR1) mRNA and the FMR1 exon 1/intron 1 boundary methylation, white matter microstructure, and executive function, in women with a FMR1 premutation expansion (PM; 55–199 CGG repeats) and controls (CGG < 44).

Methods:

Twenty women with PM without fragile X-associated tremor/ataxia syndrome (FXTAS) and 20 control women between 22 and 54 years of age completed this study. FMR1 mRNA and methylation levels for 9 CpG sites within the FMR1 exon 1/intron 1 boundary from peripheral blood samples were analyzed. To measure white matter microstructure, diffusion-weighted imaging was used, from which fractional anisotropy (FA) and mean diffusivity (MD) values from anatomic regions within the corpus callosum and cerebellar peduncles were extracted. Executive function was assessed across a range of tasks.

Results:

No differences were revealed in white matter microstructure between women with PM and controls. However, we reveal that for women with PM (but not controls), higher FMR1 mRNA correlated with lower MD values within the middle cerebellar peduncle and Paced Auditory Serial Addition Test scores, higher methylation of the FMR1 exon 1/intron 1 boundary correlated with lower MD within the inferior and middle cerebellar peduncles and longer prosaccade latencies, and higher FA values within the corpus callosum and cerebellar peduncle regions corresponded to superior executive function.

Conclusions:

We provide evidence linking white matter microstructure to executive dysfunction and elevated FMR1 mRNA and FMR1 exon 1/intron 1 boundary methylation in women with PM without FXTAS. This suggests that the FXTAS phenotype may not be distinct but may form part of a spectrum of PM involvement.