Genetic and environmental risks for specific language impairment in children

Abstract

Speci¢c language impairment (SLI) is the term used to refer to unexplained di¤culties in language acquisition in children. Over the past decade, there has been rapid growth of evidence indicating that genes play an important part in the aetiology of SLI. However, further progress in elucidating the role of genes in causing SLI is limited by our lack of understanding of the phenotype. Studies to date have been hampered by the fact that we do not know whether SLI should be treated as a discrete disorder or a continuous variable, let alone which measures should be used to identify cases, or how many subtypes there are. Recent research suggests that theoretically motivated measures of underlying processes may be better than conventional clinical diagnoses for identifying aetiologically distinct types of language impairment. There has been a tendency for researchers to embrace parsimony and look for a single cause of SLIöor in any event, to identify di¡erent subtypes, each with a di¡erent single cause. Research is reviewed that suggests that may not be a fruitful approach to SLI, and that an approach in terms of multiple risk and protective factors, which is widely adopted in medicine, is more realistic.

Neuropsychological Functioning of Siblings of Children with Autism, Siblings of Children with Developmental language Delay, and Siblings of Children with Mental Retardation of Unknown Genetic Etiology

“…Yet, the high consent rate (85% of the DLD families matching inclusion criteria) implies that these results were not slanted otherwise. These findings coincide with our previous report of lower language abilities and an increased rate of reading and arithmetic difficulties among the DLD-S (Pilowsky et al, 2003) and support the notion of their increased genetic liability for cognitive and language difficulties (Bishop, 2001;Fisher et al, 1998;Vargha-Khadem et al, 1995).…”

“…As no one comparison group ''controls'' for both the genetic and environmental aspects involved in having a sibling with autism, in the current study we employed two comparison groups. The first group comprised siblings of children with developmental language delay (DLD-S), a condition known to have a genetic component and an increased risk for siblings to demonstrate similar and other difficulties (Bishop, 2001;Bishop, North, & Donlan, 1995;Choudhury & Benasich, 2003;Dale et al, 1998;Fisher, VarghaKhadem, Watkins, Monaco, & Pembrey, 1998;VarghaKhadem, Watkins, Alcock, Fletcher, & Passingham, 1995), yet with presumably different and less severe environmental effects. The second group comprised siblings of children with mental retardation of unknown genetic etiology (MR-S), a condition resembling autism in its heterogeneity, unknown etiology, and the developmental delay evident in most cases of autism (Boutin et al, 1997), and perhaps more similar in terms of the unspecific genetic etiology and environmental effects but different in the genetic liability.…”

Cognitive and Verbal Abilities of 24- to 36-month-old Siblings of Children with Autism

“…Today, evidence is accumulating concerning a genetic influence in the appearance of specific language delays (Bishop, 2003;Spinath, Price, Dale, & Plomin, 2004) and concerning a genetic linkage between such specific language delays and autism (e.g., Bartlett et al, 2004). At age 24 months, children typically show a spurt in their verbal development (Bloom, 1998;Goldfield & Reznick, 1990).…”

Communication disorders in Nigerian children

“…SLI is an unexplained difficulty in language attainment associated with low socio-economic status, low parental education, and younger children from large families [1,12]. However, SLI has also been reported in children from affluent homes with well-educated parents thus making these generalizations unfounded and deficient in explaining the social pattern of this disorder [13]. Multifactorial causes involving genetic as well as environmental influences have been proposed in the aetiology of SLI [12,13].…”

“…However, SLI has also been reported in children from affluent homes with well-educated parents thus making these generalizations unfounded and deficient in explaining the social pattern of this disorder [13]. Multifactorial causes involving genetic as well as environmental influences have been proposed in the aetiology of SLI [12,13]. Central speech disorders are associated with general intellectual impairment which may be secondary to brain damage [10].…”