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B F Pennington

Publications and source records attributed to B F Pennington.

At least 37 records · Page 2Linked to original sources
PubMed1997

Genetic analysis of dyslexia and other complex behavioral phenotypes.

In this review, we discuss recent data on the genetics of developmental dyslexia and consider broader issues involved in the search for genes influencing complex behavioral phenotypes. These issues include 1) the need for a sophisticated analysis of the phenotype and the need for interdisciplinary collaboration between geneticists and cognitive neuroscientists, 2) the likelihood of genetic heterogeneity and non-Mendelian inheritance and the necessity for linkage methods to deal with these issues, and 3) how association analyses complement linkage analyses.

Diabetes Mellitus, Type 1↗
PubMed1996

Molecular/clinical correlations in females with fragile X.

Females who are affected by fragile X syndrome (FXS) can have significant physical, neuropsychological and emotional involvement. This study was designed to explore the relationships between these three domains and to learn how the degree of involvement in each of these phenotypic areas relates to molecular parameters including CGG repeat length and activation ratio (the proportion of normal FMR1 alleles on the active X chromosome). Three groups of females were studied: 35 women who grew up in a fragile X family but do not carry an FMR1 mutation, 92 women with a premutation, and 29 women with a full mutation. Correlations between neurocognitive, physical and emotional traits were calculated for each of the three groups. Within the full mutation group significant correlations were seen between schizotypal traits and full scale IQ. The Lie scale was significantly correlated with the physical findings index. The activation ratio correlated significantly with the measure of executive function (r = .50, P = .01). There was a trend toward correlations of activation ratio with the physical index score, outer ear prominence and IQ. CGG repeat number significantly correlated only with the physical index (r = .44, P = .01). Thus, activation ratio may be the more pertinent molecular parameter in full mutation women in determining the degree of cognitive and physical phenotypic involvement.

Adolescent↗
PubMed1996

Executive functions and developmental psychopathology.

In this paper, we consider the domain of executive functions (EFs) and their possible role in developmental psychopathologies. We first consider general theoretical and measurement issues involved in studying EFs and then review studies of EFs in four developmental psychopathologies: attention deficit hyperactivity disorder (ADHD), conduct disorder (CD), autism, and Tourette syndrome (TS). Our review reveals that EF deficits are consistently found in both ADHD and autism but not in CD (without ADHD) or in TS. Moreover, both the severity and profile of EF deficits appears to differ across ADHD and autism. Molar EF deficits are more severe in the latter than the former. In the few studies of more specific EF tasks, there are impairments in motor inhibition in ADHD but not in autism, whereas there are impairments in verbal working memory in autism but not ADHD. We close with a discussion of implications for future research.

Adolescent↗
PubMed1996

Intact and impaired memory functions in autism.

This study examined memory functions in individuals with autism. Based on previous evidence of executive function (EF) deficits, we hypothesized that subjects with autism would demonstrate a pattern of intact and impaired memory functions similar to that found in other groups with EF deficits, such as patients with frontal lobe pathology. We compared the performance of high-functioning children and adolescents with autism (n = 19) and clinical comparison subjects (n = 19) matched on sex, CA, and VIQ on measures of memory and EF. The group with autism performed significantly worse than comparison subjects on measures of temporal order memory, source memory, supraspan free recall, working memory, and EF, but not on short- and long-term recognition, cued recall, or new learning ability, consistent with the predictions of the EF theory. The cognitive measures were significantly more intercorrelated in the autism group than the comparison group, consistent with a limit in central cognition.

Adolescent↗
PubMed1996

Imitation and pantomime in high-functioning adolescents with autism spectrum disorders.

A study was designed to test 2 alternative hypotheses--a symbolic hypothesis and an executive function hypotheses--for the imitation and pantomime deficits found in previous studies of autism. The subjects were 17 adolescent high-functioning subjects with autism spectrum disorders and 15 clinical comparison subjects who were matched on chronological age and verbal IQ. Meaning and sequence were manipulated in facial and manual imitation tasks. Sequence was manipulated in the pantomime and control tasks. Recognition memory and motor control tasks were matched to the experimental tasks. The results provided no support for the symbolic deficit hypothesis; meaning aided rather than hindered the performance of the group with autism. Partial support for the executive deficit hypothesis was found. There were no group differences on motor control tasks, and few on the memory control tasks, arguing against deficits in motor initiation, basic motor coordination, or visual recognition memory.

Adolescent↗
PubMed1995

Quantitative trait locus for reading disability: correction.

In the news article "Can risky mergers save hospital-based research?" by Wade Roush (19 May, p. 968), the statement that University Hospitals of Cleveland rose from 20th in the rankings of teaching hospitals funded by the National Institutes of Health (NIH) in 1991 to 12th at present was incorrect. In fact, it was Case Western Reserve University (CWRU), with which University Hospitals of Cleveland is affiliated, that received $69 million in NIH grants in 1993, making it the 20th largest recipient of such grants among medical centers; the university then received $97 million in 1994, raising its rank to 12th. About $15 million of the increase, or 53%, was attributable to CWRU's 1992 affiliation with Henry Ford Hospital in Detroit. Other hospitals affiliated with Case Western include MetroHealth Medical Center, Mount Sinai Medical Center, St. Luke's Medical Center, and Cleveland Veterans' Affairs Medical Center.

Chromosome Mapping↗
PubMed1994

Quantitative trait locus for reading disability on chromosome 6.

Interval mapping of data from two independent samples of sib pairs, at least one member of whom was reading disabled, revealed evidence for a quantitative trait locus (QTL) on chromosome 6. Results obtained from analyses of reading performance from 114 sib pairs genotyped for DNA markers localized the QTL to 6p21.3. Analyses of corresponding data from an independent sample of 50 dizygotic twin pairs provided evidence for linkage to the same region. In combination, the replicate samples yielded a chi 2 value of 16.73 (P = 0.0002). Examination of twin and kindred siblings with more extreme deficits in reading performance yielded even stronger evidence for a QTL (chi 2 = 27.35, P < 0.00001). The position of the QTL was narrowly defined with a 100:1 confidence interval to a 2-centimorgan region within the human leukocyte antigen complex.

Adolescent↗
PubMed1994

Emotional and neurocognitive deficits in fragile X.

We have studied the neurocognitive deficit in premutation and full mutation women as compared to control women and to explore the relationship between those deficits and the incidence of emotional problems. Four groups of women were examined: two fragile X (fra(X)) negative control groups, one of which grew up in fra(X) families and one not; and two DNA positive groups, one with a premutation (CGG repeats < 200) and one with an expanded mutation (CGG repeats > 200). All women were assessed using the MMPI-2, the SADS-L, and a battery of neuropsychological tests. Full mutation women had lower scores on composite measures of executive function and nonverbal function. There was no difference between the groups in terms of the lifetime incidence of depressive and anxiety disorders on the SADS-L. Full mutation women displayed Lie scales higher than the other groups on the MMPI-2. Neurocognitive measures were not related to SADS-L diagnoses but were related to the Lie scale on the MMPI-2. Finally, number of CGG repeats was related to the neuropsychological variables and the Lie scale.

Adult↗
PubMed1994

Commingling and segregation analysis of reading performance in families of normal reading probands.

This paper reports the results of commingling and genetic segregation analyses performed on a quantitative reading phenotype in 125 families ascertained through normal, nondisabled readers. Commingling analysis using SKUMIX suggested that the reading phenotype best fit a skewed, single distribution model. Complex segregation using POINTER was then performed on the power adjusted data. While there were some analytical ambiguities and complexities, the segregation analysis indicated that there was familial transmission of the phenotype and that a significant percentage of the variance in this phenotype could be attributed to a major gene with dominance. Because the estimated frequency of the putative dominant allele is .35, 57% of the population would carry at least one copy of this allele. This common allele, with low penetrance, accounted for 54% of the phenotypic variance in reading scores. These findings are considered in the context of our earlier report of major gene influence ona qualitative dyslexic phenotype in a sample of 133 dyslexic proband families that were originally matched to the present sample of control families (Pennington et al., 1991). The applicability of a classic single gene, multifactorial-polygenic, and oligogenic or QTL models for reading ability/disability is discussed.

Child↗
PubMed1994

Social cognition skills among females with fragile X.

Emotion perception and perspective-taking skills were examined among women with or without the fragile X gene. The performance of 56 control women was compared to the performance of 46 women who were carriers of the fragile X gene. Twenty-seven of the carrier women had 0-1% cytogenetic expression and did not appear affected by the gene, whereas the remaining 19 women had > or = 2% cytogenetic expression and did appear affected by the gene. The emotion perception task employed was one for which deficits have been reported among individuals with autism. The results show that performance on this emotion-perception test and the perspective-taking measure was significantly related to full-scale IQ scores, but not to fragile X group status when effects of IQ were removed. Thus the results do not support the hypothesis that perspective-taking or emotion perception deficits are a component of the fragile X phenotype in females and represent an important differentiation between fragile X and autism.

Adolescent↗
PubMed1993

Can standard measures identify subclinical markers of autism?

This study compared the executive function and theory-of-mind abilities of siblings of autistic individuals to those of siblings of learning-disabled controls. Three different analyses of the dependent measures provided convergent support for a potential subclinical marker in the executive function domain. No group differences in theory-of-mind abilities were found. However, power analyses revealed that the measures employed in this study, which are typically used with autistic individuals, were not sufficiently sensitive to detect any group differences that might exist in "unaffected" family members. Suggestions for future research are provided, including the need to develop more sensitive tasks that produce larger effects and measure more elementary cognitive operations.

Adolescent↗
PubMed1993

Executive function and social communication deficits in young autistic children.

Preschool-aged, autistic children were compared with both developmentally delayed children of similar non-verbal mental age and normally developing children of similar verbal skill on measures of executive function and social communication skills. Autistic children exhibited significantly more perseverative responses on a test of executive function when compared to both comparison groups. Autistic children also exhibited significantly fewer joint attention and social interaction behaviors. Moreover, a significant relationship was found between executive function skill and the two social communication skills, which was independent of group membership or verbal ability. Competing hypotheses to account for the relationship between executive function deficits and social communication deficits in autism are discussed.

Attention↗
PubMed1993

Hyperactivity and spelling disability: testing for shared genetic aetiology.

The influence of genetic factors in the comorbidity of spelling disability and hyperactivity was investigated in two samples of 190 and 260 same sex twin pairs. The method of bivariate group heritability was used to estimate the genetic correlation for spelling disability and hyperactivity. A similar though not statistically significant value for the genetic correlation was obtained for the two samples (0.29 and 0.42). It was estimated that approximately 75% of the co-occurrence of these two conditions was due to shared genetic influences.

Adult↗
PubMed1993

The neurocognitive phenotype of female carriers of fragile X: additional evidence for specificity.

The specificity of the neurocognitive profile among women with the fragile X gene, in relation to cytogenetic expression, was examined among 22 women with > or = 2% expression, 35 0% obligate carriers, and 60 controls. Measures were obtained for intellectual ability; achievement; and verbal, nonverbal, memory, and executive functions. Findings show that no group consistently demonstrated global deficits in the verbal, nonverbal or memory domains. In contrast, even when controlling for the effects of IQ, the expressing women exhibited (1) deficits on measures of executive function, (2) deficits in measures of attention and visual-spatial skills, and (3) enhanced performance on verbal, but not figural, memory. No deficits were seen among obligate carriers. This study supports the notion that executive function deficits and/or visual-spatial skills may account for the behavioral and cognitive manifestations of fragile X.

Adolescent↗
PubMed1992

Dyslexia.

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Dyslexia↗