Neurocognitive function and brain imaging in Turner syndrome--preliminary results

The speech and language profile of a child with Turner Syndrome- a case study

BACKGROUND

Turner syndrome is a genetic disorder that affects only females. It has specific cognitive characteristics, but speech and language data are scarce.

METHODS AND PROCEDURES

Prospective case report; we report a girl aged seven's cognitive and speech and language profile.

RESULTS

Cognitive assessment shows higher performance IQ (PIQ), and atypical cognitive profile for Turner syndrome. Speech and language assessment show a significant difference between receptive and expressive language levels. Although the girl did comprehend most of the language structure, there was a lack of it in spontaneous speech. She demonstrated inconsistency in the use of language morphology and complex linguistic structures, primarily because of significant inconsistency in her sound production. Although she produced the majority of phonemes correctly in isolation, her spontaneous speech production was incomprehensible.

CONCLUSION

Case studies of speech and language development may reveal a specific characteristic in the cases with Turner syndrome to delineate genetic factors from individual developmental variabilities.

Brain Development in School-Age and Adolescent Girls: Effects of Turner Syndrome, Estrogen Therapy, and Genomic Imprinting

BACKGROUND

The study of Turner syndrome (TS) offers a unique window of opportunity for advancing scientific knowledge of how X chromosome gene imprinting, epigenetic factors, hormonal milieu, and chronologic age affect brain development in females.

METHODS

We described brain growth trajectories in 55 girls with TS and 53 typically developing girls (258 magnetic resonance imaging datasets) spanning 5 years. Using novel nonparametric and mixed effects analytic approaches, we evaluated influences of X chromosome genomic imprinting and hormone replacement therapy on brain development.

RESULTS

Parieto-occipital gray and white matter regions showed slower growth during typical pubertal timing in girls with TS relative to typically developing girls. In contrast, some basal ganglia, cerebellar, and limited cortical areas showed enhanced volume growth with peaks around 10 years of age.

CONCLUSIONS

The parieto-occipital finding suggests that girls with TS may be particularly vulnerable to altered brain development during adolescence. Basal ganglia regions may be relatively preserved in TS owing to their maturational growth before or early in typical pubertal years. Taken together, our findings indicate that particular brain regions are more vulnerable to TS genetic and hormonal effects during puberty. These specific alterations in neurodevelopment may be more likely to affect long-term cognitive behavioral outcomes in young girls with this common genetic condition.

Ocular motor indicators of executive dysfunction in fragile X and Turner syndromes

Fragile X and Turner syndromes are two X-chromosome-related disorders associated with executive function and visual spatial deficits. In the present study, we used ocular motor paradigms to examine evidence that disruption to different neurological pathways underlies these deficits. We tested 17 females with fragile X, 19 females with Turner syndrome, and 40 females with neither disorder who comprised the comparison group. Group differences emerged for both the fragile X and Turner syndrome groups, each relative to the comparison group: Females with fragile X had deficits in generating memory-guided saccades, predictive saccades, and saccades made in the overlap condition of a gap/overlap task. Females with Turner syndrome showed deficits in generating memory-guided saccades, but not during either the predictive saccade or gap/overlap task. Females with Turner syndrome, but not females with fragile X, showed deficits in visually guided saccades and anti-saccades. These findings indicate that different brain regions are affected in the two disorders, and suggest that different pathways lead to the similar cognitive phenotypes described for fragile X and Turner syndromes.

A review of neuropsychological and motor studies in Turner Syndrome

We reviewed the literature on Turner Syndrome (TS) from 1962 until March 2003 with respect to the following questions: Is there a consistent pattern of cognitive and/or motor dysfunction in TS girls and if so, is there an explanation for the disturbance? Many studies indicate that girls with TS have a disharmonic IQ profile: a verbal IQ that seems to be at a (nearly) normal level and a decreased PIQ. This profile remains into adulthood. Visual-spatial problems are mentioned most frequently and there is some evidence for a relationship to particular neuro-anatomical structures, hormonal dysfunction, and genotype. Although much less research has been done on motor performance in TS, there is clear evidence that it is disturbed too in TS. Many authors emphasize the interaction between somatic, psychological and social factors, but we did not find a clear theoretical framework explaining this relationship. We argue that there may be two independent problems: a visuospatial and a motor deficit possible related to specific genotypes and both have implications for functioning in daily life.

Oral fluency and narrative production in children with Turner's syndrome

Despite good verbal skills, children with Turner's syndrome (TS) have been found to perform poorly on oral fluency tasks. Explanations for this impairment were explored in a study of 9-12-year-old children with TS. The children with TS were found, as expected, to have impaired levels of retrieval on initial letter fluency tasks, in comparison to their peers. Children with TS were also found to have receptive vocabularies which were significantly better than controls, indicating that the weak performance on oral fluency cannot be attributed to lower vocabulary levels. Naming skills were normal for children with TS, indicating that oral fluency scores cannot be attributed to generalised problems with lexical access. Analysis of the content of fluency performance indicated clusters of words within sub-categories which were of normal size but there were fewer switches between clusters than for controls and fewer returns to previously successful clusters. Additionally, a significantly larger proportion of the words generated were of low frequency (e.g. Assyrian, antediluvian) and the children with TS did not thereby show a normal frequency effect in word retrieval. One explanation is that these reflect abnormal action of executive language retrieval processes. Within narrative production, picture description was normal. However, in relation to narrative tasks, hypothesised to place greater executive demands, there was impairment which was significantly greater for narratives of yesterday than narratives of organising a party. This impairment within the narrative generation tasks could be attributable to a selective impairment within executive retrieval skills, or could represent an impairment in episodic memory or the executive processes involved in its retrieval.

Math learning disability and math LD subtypes: evidence from studies of Turner syndrome, fragile X syndrome, and neurofibromatosis type 1

The present study examined whether indicators of math learning disability are observed in 5- and 6-year-olds with neurofibromatosis type 1 (NF1) and in 5- to 6-year-old girls with Turner syndrome or fragile X syndrome. Data from 14 girls with Turner syndrome, 9 girls with fragile X syndrome, and 11 children with NF1 were compared to data from control participants matched on age, sex, IQ score, and grade level. The results indicate that girls with fragile X syndrome or Turner syndrome are significantly more likely to have specific math difficulties relative to their control group, with a larger effect size demonstrated by the group with Turner syndrome. Young children with NF1 had a heterogeneous profile not suggestive of specific math disability. The results are discussed in terms of their implications for understanding math disability subtypes and the identification of math difficulty in the early school years.

Age-related perception of stature, acceptance of therapy, and psychosocial functioning in human growth hormone-treated girls with Turner's syndrome

This study evaluated the perception of stature, acceptance of therapy, and psychosocial functioning in relation to age at onset and time on treatment during 2 yr of GH therapy in 31 girls with Turner's syndrome grouped by age (group A: 3.7-5.8 yr, n = 9; group B: 7.2-11.8 yr, n = 13; group C: 12.5-16.4 yr, n = 9). The growth response after 2 yr was significant in the 3 groups when calculated in terms of growth norms for untreated Turner girls (mean increase in height SD score: +1.2, +1.5, and +1.1, respectively). The effect was less marked in terms of growth norms for normal girls, particularly in group B (+0.5 SD score). Height was perceived as a problem by most patients, except in the youngest girls at the start of treatment (group A) and in the majority of the adolescents after 2 yr of GH therapy (group C), without evidence of relation to growth response during therapy. The GH injections were fairly well accepted by all patients, except those younger than 6 yr. In all patients, expected adult height was unrealistic and became more realistic with age, whereas no consistent changes were observed in relation to growth response to GH therapy. The Child Behavior Checklist revealed elevated mean scores at the behavioral subscales of attention problems (group A and B), social problems, withdrawal, and anxiety-depression (most obviously in group B). No significant changes were seen during GH therapy. In group C, an elevated mean social problem score at the Youth Self Report and a low mean social self-esteem score at the Self-Esteem Inventory were observed before therapy and showed a significant improvement during 2 yr of GH treatment. These results, however, might be biased due to an increase in social desirability during therapy. We conclude that the perception of height, acceptance of GH therapy, and psychosocial functioning in girls with Turner's syndrome show important differences between age groups, with only slight changes observed during GH therapy.

Neurodevelopmental effects of X monosomy: a volumetric imaging study

Thirty girls with Turner syndrome (TuS) were compared with 30 individually age-matched controls on volumetric brain measures derived from magnetic resonance imaging and on measures of psychological functioning. As expected, girls with TuS performed more poorly on visual-spatial and intellectual measures relative to controls, and were rated by their parents as having more significant problems in attention and social behaviors. Although no group differences in overall cerebral or subcortical volumes were observed, the regional distribution of gray and white matter differed across groups in both right and left parietal regions. Differences in total tissue volume ratios were seen for both right and left parietal areas, but differences in individual gray and white matter ratios were seen exclusively in the right parietal regions. In general, girls with TuS had a smaller proportion of tissue (gray and white) within the right and left parietal regions, and a larger proportion of tissue within the right inferior parietal-occipital region relative to girls in the control group. These data suggest a potentially important role for X chromosome genes and/or sex steroids in the development and specialization of brain structure and function.