Genetic and phenotypic effects of phonological short-term memory and grammatical morphology in specific language impairment

Authors

  • M. Falcaro,

    1. Faculty of Medical and Human Sciences, The University of Manchester, Manchester, and The Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
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  • A. Pickles,

    Corresponding author
    1. Faculty of Medical and Human Sciences, The University of Manchester, Manchester, and The Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
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  • , D. F. Newbury,

    1. Faculty of Medical and Human Sciences, The University of Manchester, Manchester, and The Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
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  • L. Addis,

    1. Faculty of Medical and Human Sciences, The University of Manchester, Manchester, and The Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
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  • E. Banfield,

    1. Faculty of Medical and Human Sciences, The University of Manchester, Manchester, and The Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
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  • S. E. Fisher,

    1. Faculty of Medical and Human Sciences, The University of Manchester, Manchester, and The Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
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  • A. P. Monaco,

    1. Faculty of Medical and Human Sciences, The University of Manchester, Manchester, and The Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
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  • Z. Simkin,

    1. Faculty of Medical and Human Sciences, The University of Manchester, Manchester, and The Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
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  • G. Conti-Ramsden,

    1. Faculty of Medical and Human Sciences, The University of Manchester, Manchester, and The Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
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  • The SLI Consortium

    1. Faculty of Medical and Human Sciences, The University of Manchester, Manchester, and The Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
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  • 1

    Members of the SLI Consortium: The Wellcome Trust Centre for Human Genetics, University of Oxford: D. F. Newbury, E. Banfield, L. Addis, J. D. Cleak, S. E. Fisher, L. R. Cardon and A. P. Monaco. Cambridge Language and Speech Project (CLASP): M. J. Merricks and I. M. Goodyer. Child and Adolescent Psychiatry Department and Medical Research Council Centre for Social, Developmental, and Genetic Psychiatry, Institute of Psychiatry: E. Simonoff and P. F. Bolton. Newcomen Centre, Guy’s Hospital: V. Slonims and G. Baird. Department of Child Health, University of Aberdeen: A. Everitt, E. Hennessy, D. Shaw and P. J. Helms. The Raeden Centre and Grampian University Hospitals Trust: A. D. Kindley. Speech and Hearing Sciences, Queen Margaret University College: A. Clark and J. Watson. Department of Reproductive and Developmental Sciences, University of Edinburgh: A. O’Hare. Molecular Medicine Centre, University of Edinburgh: J. Seckl. Department of Speech and Language Therapy, Royal Hospital for Sick Children, Edinburgh: H. Cowie. Department of Educational and Professional Studies, University of Strathclyde: W. Cohen. Academic Unit of Neurology, University of Sheffield Medical School: J. Nasir. Department of Experimental Psychology, University of Oxford: D. V. M. Bishop. Human Communication and Deafness, School of Psychological Sciences, University of Manchester: Z. Simkin and G. Conti-Ramsden. Biostatistics Group, University of Manchester: M. Falcaro and A. Pickles.

*A. Pickles, Biostatistics Group, The University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, UK. E-mail: andrew.pickles@manchester.ac.uk

Abstract

Deficits in phonological short-term memory and aspects of verb grammar morphology have been proposed as phenotypic markers of specific language impairment (SLI) with the suggestion that these traits are likely to be under different genetic influences. This investigation in 300 first-degree relatives of 93 probands with SLI examined familial aggregation and genetic linkage of two measures thought to index these two traits, non-word repetition and tense marking. In particular, the involvement of chromosomes 16q and 19q was examined as previous studies found these two regions to be related to SLI. Results showed a strong association between relatives’ and probands’ scores on non-word repetition. In contrast, no association was found for tense marking when examined as a continuous measure. However, significant familial aggregation was found when tense marking was treated as a binary measure with a cut-off point of −1.5 SD, suggestive of the possibility that qualitative distinctions in the trait may be familial while quantitative variability may be more a consequence of non-familial factors. Linkage analyses supported previous findings of the SLI Consortium of linkage to chromosome 16q for phonological short-term memory and to chromosome 19q for expressive language. In addition, we report new findings that relate to the past tense phenotype. For the continuous measure, linkage was found on both chromosomes, but evidence was stronger on chromosome 19. For the binary measure, linkage was observed on chromosome 19 but not on chromosome 16.

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