Heritability of Poor Language Achievement Among Twins

The genetic and environmental etiology of speech and broader language skills was examined in terms of their concurrent relationships in young children; their longitudinal association with reading; and the role they play in defining the 'heritable phenotype' for specific language impairment (SLI). The work was based on a large sample of 4½-year-old twins, who were assessed at home on a broad range of speech and language measures as part of the Twins Early Development Study. We found that genetic factors strongly influence variation in young children's speech in typical development as well as in SLI, and that these genetic factors also account for much of the relationship between early speech and later reading. In contrast, shared environmental factors play a more dominant role for broader language skills, and in relating these skills to later reading; isolated impairments in language as opposed to speech appear to have largely environmental origins.Learning Outcomes-1) Readers will be able to discuss some of the ways in which behavioural genetic methods can make a useful contribution to the field of communication disorders. 2) Readers will be able to compare the genetic and environmental contributions to general language versus speech skills in young children. 3) Readers will be able to describe the likely relationship between early speech and language and later reading development, in terms of shared genetic and environmental resources. 4) Readers will be able to discuss how different ascertainment methods for clinical samples may lead to very different understandings of the nature of a disorder such as specific language impairment. Keywords etiology; genes; environment; speech; language; reading; SLI The current paper explores the relationship between speech and language skills in young children, using a behavioural genetics approach. I will illustrate this theme using three recently completed studies: the first examines the nature of the relationship between speech and language in terms of the shared genetic and environmental factors that influence them; the second looks at the extent to which genes and environments that are important for speech and language skills in preschool also have long term impact on children's reading; and the third study considers how a differentiation between speech and broader language skills may be useful for clarifying the 'heritable phenotype' in specific language impairment. Background on TEDS and the twin method

Section: Speech or Language: The Heritable Phenotype In Sli?mentioning

confidence: 90%

Genetic and environmental influences on early speech, language and literacy development

Hayiou‐Thomas

2008

“…Findings from twin, adoption, and genetic linkage studies provide further support for shared genetic influences on SSD, LI, and reading disorders (Bishop, North, & Donlan, 1995;Felsenfeld & Plomin, 1997;Lewis & Thompson, 1992;Stein et al, 2004;Tomblin & Buckwalter, 1998). In a recent study, Stein et al (2004) examined a region on chromosome 3 that was previously associated with RD.…”

Section: Genetic Support For the Subtyping Of Ssdmentioning

confidence: 93%

Dimensions of early speech sound disorders: A factor analytic study

Lewis

Freebairn

Hansen

et al. 2006

The goal of this study was to classify children with speech sound disorders (SSD) empirically, using factor analytic techniques. Participants were 3-7-year olds enrolled in speech/language therapy (N = 185). Factor analysis of an extensive battery of speech and language measures provided support for two distinct factors, representing the skill dimensions of articulation/phonology and semantic/ syntactic skills. To validate these factors, 38 of the children were followed to school age to re-evaluate speech and language skills and assess reading/spelling achievement. The validity of the two factors was supported by their differential associations with school-age reading and spelling achievement, persistence of SSD, and affection status in family members. A closer relationship of the family member to the proband and male gender predicted higher odds of a disorder. The findings suggest that articulation/phonology and language abilities are at least partially independent in children with SSD and that these constructs have distinct clinical and biological correlates. Learning outcomes: The reader will develop knowledge about subtypes of speech sound disorders, understand the relationship between early speech sound disorders and later reading and spelling difficulties, and obtain information concerning familial transmission of speech sound disorders. #

“…Findings from these studies indicate that 23-40% of firstdegree family members of individuals with speech-sound/language disorders are affected. Findings from twin and adoption studies also suggest a genetic component to speech and language (Bishop, North, & Donlan, 1995;Felsenfeld & Plomin, 1997;Lewis & Thompson, 1992;Tomblin & Buckwalter, 1998).…”

Section: Limitations Of Previous Studiesmentioning

confidence: 99%

Family pedigrees of children with suspected childhood apraxia of speech

Lewis

Freebairn

Hansen

et al. 2004

Forty-two children (29 boys and 13 girls), ages 3-10 years, were referred from the caseloads of clinical speech-language pathologists for suspected childhood apraxia of speech (CAS). According to results from tests of speech and oral motor skills, 22 children met criteria for CAS, including a severely limited consonant and vowel repertoire, difficulty sequencing syllables, and inconsistent and unusual errors. Family pedigrees for these children were constructed through parent interviews and direct testing of nuclear family members. Familial aggregation for speech-sound and language disorders was demonstrated with 86% reporting at least one nuclear family member affected. Based on parent report, 13 of the 22 children (59%) had at least one affected parent. However, CAS was evident in only two siblings of probands with CAS and two probands with other speech-sound disorders. Based on testing, overall affection rates of speech-sound/language disorders were higher in families of children with CAS than in families of children with other speech-sound disorders.Mothers of children with CAS demonstrated a higher affection rate than mothers of children with other speech-sound disorders. A sex-related threshold model of transmission was also supported with brothers more often affected than sisters for male probands only. If our inclusionary criteria for CAS are valid, these findings support a general verbal trait deficit hypothesis. Learning outcomes: (1) As a result of this activity, the participant will understand potential familial risk factors for CAS; (2) will differentiate aggregation for speech-sound and language disorders in families with CAS from families of children who have other speech-sound disorders; (3) will