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Language disorders in children: What can they tell us about genes and brains?. Dorothy Bishop University of Oxford. Specific language impairment (SLI). Diagnosed in children when language does not follow normal developmental course

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language disorders in children what can they tell us about genes and brains

Language disorders in children:What can they tell us about genes and brains?

Dorothy Bishop

University of Oxford

specific language impairment sli
Specific language impairment (SLI)
  • Diagnosed in children when language does not follow normal developmental course
  • Problems with language structure (phonology and syntax) common
  • Not due to hearing loss, physical abnormality, acquired brain damage
  • Normal development in other areas

Thursday, 9 January, 2003, 11:15 GMT

Daily grunt parents hold children back

Not enough talking going on

Parents who do little more than grunt at their children every day are damaging their language development, a literacy expert has said.

Alan Wells, director of the Basic Skills Agency, says parents no longer talk to their children and instead just let them sit in front of the television or computer for hours.

evidence against poor language environment as cause of sli
Evidence against poor language environment as cause of SLI
  • Most children develop adequate language despite very variable levels of language input from parents
    • E.g. different cultures
    • Children in exceptional circumstances, including hearing children of deaf parents
    • Twin studies: dizygotic twins growing up in same environment can be very different
is brain damage implicated
Is brain damage implicated?
  • Early idea of “continuum of reproductive casualty” - i.e. brain damage incurred around time of birth might lead to learning disabilities


hemorrhage : a


feature of


evidence against brain damage as cause of sli
Evidence against brain damage as cause of SLI
  • No obvious signs of neurological impairment in most cases of SLI
  • No excess of perinatal problems in SLI
  • Children who do have focal lesions affecting the language areas don’t develop SLI - see Basser 1962!
sli family aggregation
SLI: Family aggregation

Rates of language/learning difficulties higher in relatives of those with SLI, compared with controls

Twin Study Method

MZ twins: genetically identical

DZ twins: share 50% of polymorphic genes


Is concordance for disorder higher in MZ than in DZ twins?

twin studies of sli
Twin studies of SLI



same-sex twins


Lewis & Thompson, 1992 .86 .48

Bishop et al, 1995 .70 .46

Tomblin & Buckwalter, 1998 .96 .69

Hayiou-Thomas et al, 2005 .36 .33

Bishop & Hayiou-Thomas, 2008 .88 .35

(same sample, criteria of SALT contact)


Evidence for substantial genetic influence on SLI

But lots of questions remain, e.g.:

  • Can SLI be caused by a single gene?
  • Is SLI a single condition, or are there etiologically distinct subtypes?
  • What (if anything) does this say about evolution of language?
single gene disorder ke family
Single gene disorder: KE family

Hurst et al, 1990; Gopnik, 1990;

Vargha-Khadem et al, 1995

Nature, October 4th 2001

A forkhead-domain gene is mutated

in a severe speech and language disorder

Lai, C. S., Fisher, S. E., Hurst, J. A.,

Vargha-Khadem,F., & Monaco, A.

  • FOXP2: gene on chromosome 7q31
  • Single base mutation in affected individuals
  • No allelic variation in people with normal language
Nature, August 22nd 2002

Molecular evolution of FOXP2, a gene

involved in speech and language

Enard, W., Przeworski, M., Fisher, S. E., Lai, C. S. L.

Wiebe, V., Kitano, T., Monaco, A. P., Paabo, S.

  • FOXP2 differs in man and mouse in only 3 amino acid positions
  • FoxP2 differs in man vs. chimp, gorilla, rhesus macaque in 2 amino acid positions
  • i. e. 2/3 differences between human/mouse occurred on human lineage after separation from chimpanzee
is foxp2 a grammar gene
Is FOXP2 a 'grammar gene'?


  • FOXP2 is a transcription factor: regulates expression of many other genes, and expressed in multiple organs
  • Affected members of KE family have problems beyond grammar
  • Abnormality of subcortical regions involved in motor control

(Watkins et al, 2002)

Nevertheless,affected members poor at syntactic tasks, even

when no speech is required, e.g.

The elephant pushing the boy is big

how to characterise foxp2
How to characterise FOXP2
  • A transcription factor that affects expression of many other genes, and is expressed in multiple organs
  • Human version of gene may be important for building brain areas involved in extracting hierarchical structure from linear input
q1 can sli be caused by a single gene
Q1. Can SLI be caused by a single gene?
  • Yes, in case of FOXP2
  • But! This is the exception rather than the rule
  • No abnormality of FOXP2 seen in majority of cases of SLI
  • Pedigree analysis does not show straightforward pattern suggestive of single gene disorder
sli as complex multifactorial disorder
SLI as complex multifactorialdisorder
  • Aggregates but does not segregate in families
  • Typical etiology for common disorders

e.g. heart disease, diabetes

the quest for heritable phenotypes
The quest for heritable phenotypes
  • Need to move from clinical diagnosis to measures of underlying impairment
some promising component skills
Some promising component skills
  • Auditory processing skills (e.g., Tallal)
  • Morphosyntax (e.g., Rice & Wexler)
  • Phonological short-term memory (e.g., Gathercole & Baddeley)
children s nonword repetition test cnrep
Children’s Nonword Repetition Test (CNRep)

Gathercole and Baddeley, 1990

Child listens to spoken nonwords and repeats, e.g.

2 syllables: hampent

3 syllables: dopelate

4 syllables: confrantually

5 syllables: pristoractional

nonword repetition
Nonword repetition

NB performance

near ceiling on

2 syllable nonwords

data from Bishop et al, 1996

Genetic analysis:

quantitative rather than categorical approach

defries fulker df analysis
nonshared environment only

shared environment only

genes only



DeFries-Fulker (DF) analysis








involvement of phonological stm in syntax learning
Involvement of phonological STM in syntax learning?
  • Baddeley et al (1998) notion of phonological loop as buffer to hold information while computing syntactic relations
  • Joanisse & Seidenberg (1998) problems that seem specific to grammar may be secondary consequences of phonological memory deficit

To get beyond correlational evidence, can use twin method to test for common origins in different deficits

Twin Sample6 yr olds from community twin sample (TEDS), biased to include those with language difficulties
  • 65 MZ and 67 DZ pairs with ‘low language’ on basis of parental report at 4 yr
  • 37 MZ and 29 DZ control pairs (neither ‘low language’)

Bishop et al., 2006

nonword repetition1
Nonword repetition

NB test not given to 19 children with unintelligible speech

Residual score: total correct on 3-, 4- and 5-syllable nonsense words predicted from the total of 2-syllable words: gives purer measure of memory

Rice-Wexler task:

test of grammatical morphology

“Here the boy is raking; now he is done.

Tell me what he did”.

Here’s a farmer.

Tell me what a

farmer does.

n children inflecting verbs
N children inflecting verbs

Mann Whitney; z = 5.75, p < .001

Bishop et al., 2006

nonword repetition probands cotwin z scores on verbs
Nonword repetition probands; cotwin z-scores on verbs

h2g.xy = .32

(95%CI = .71)

co-twin verb

proband phonSTM

co-twin verb

proband phonSTM

Genetic risk 2

Genetic risk 1

Conclusions from twin study




STM deficit

MZ twins more similar to each other than DZ, but only within-trait

MZ twins more similar to each other than DZ


STM deficit


STM deficit

are there separate subtypes of sli
Are there separate subtypes of SLI?
  • Poor phonological STM
  • Poor grammatical morphology
children with co-occurring

deficits are most likely

to be identified with SLI

phonological STM deficit

morphosyntax deficit

Suggests language is a strongly canalised function:

will develop despite variation in underlying cognitive bases

q2 is sli a single condition or are there heritable subtypes
Q2. Is SLI a single condition, or are there heritable subtypes?

Neither seems true!

  • Notion of disorder that arises only when there is more than one underlying deficit
  • Predicts relatives will show deficit without necessarily showing disorder
  • Predict genetic variants will be risk factors rather than act as single causes
study of parents
Study of parents

Barry, J. G., Yasin, I., & Bishop, D. V. M. (2007). Heritable risk factors associated with language impairments. Genes, Brain and Behavior, 6, 66-76.

mean language literacy scores in parents
Mean language/literacy scores in parents

NB significant differences maintained when self-report LI excluded

sli consortium molecular genetic studies
SLI consortium: molecular genetic studies
  • Have found 3 genetic variants that are associated with nonword repetition in SLI samples
  • Two genes on chromosome 16 act additively; other gene is downstream target of FOXP2
  • Poor performance on verb morphology linked to site on chromosome 19
genes associated with nonword repetition deficits
Genes associated with nonword repetition deficits

Very different from FOXP2

  • 'Risk' variants are common in the general population
  • Associated with a drop in nonword repetition score, but of moderate magnitude

Two genes on chromosome 16

Gene 1

Gene 2

figures from Dianne Newbury

  • Supports notion that language involves multiple cognitive processes
  • Syntactic deficits not reducible to more basic cognitive process (at least, not to those measured here)
  • Search for single cause explanations of SLI may be doomed - language is resilient enough to survive one deficit
thanks to
Thanks to:

Caroline Adams & Courtenay Norbury

6 yr old twin testing project

Robert Plomin

Twins Early Development Study

Mabel Rice

making prepublication test materials available

Dianne Newbury, Tony Monaco, Simon Fisher

making prepublication genetic results available

Dorothy Bishop

Oxford Study of Children’s

Communication Impairments,

Department of Experimental


South Parks Road,


OX1 3UD,


[email protected]

References available on: