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syndrome). Furthermore, there is evidence that DGS remains undiagnosed in many children as an isolated speech and language disorder or developmental delays in the presence of few or no physical abnormalities (Niklasson, Rasmussen, Óskarsdóttir, & Gillberg, 2001).
There is a large literature on the behavioural and psychiatric profiles of individuals with 22q11 deletion syndrome (see Scandurra, Scordo, Canitano, & de Bruin, 2013 and references within);
however, within the paediatric population information is limited. The large variation of the phenotype can make diagnosis more difficult. According to some researchers, the median age of diagnosis is 6.5 years (Solot, Handler, Gerdes, McDonald-McGinn, Moss, Wang, Cohen, Randall, Larossa, &
Driscoll, 2000).
The majority of DGS individuals show relatively mild cognitive deficits, including sometimes mild mental retardation (MMR, i.e. IQ 51-0), with verbal IQ often significantly higher than performance IQ and/or non-verbal IQ. However, there are reports of individuals with low normal intelligence (IQ 71-85) and some with an IQ in excess of 85 (Niklasson et al., 2001). Individuals with DGS show relative strengths in verbal ability, rote processing, verbal memory, reading, and spelling. In addition, there are reported weaknesses in language abilities, attention, working memory, executive functions, visuospatial memory, and psychosocial functioning (see Woodin et al., 2001 and references within for both points).
In particular, research on the manifestations of speech and language disorders in DGS children is not prominent, despite communication impairment being one of the hallmark deficits of the syndrome. In DGS, speech and language delays have been reported in early childhood with persistent language impairment in preschool ages in the areas of word finding, vocabulary, syntax, and discourse (see Persson, Niklasson, Óskarsdóttir, Johansson, Jönsson, & Söderpalm, 2006 and references within).
Preschool children with DGS often have a reduced vocabulary size, reduced sentence length, and delayed use of grammatical structures. Also, expressive language delays are more severe than receptive language delays (Persson et al., 2006), but this may not always be the case. Moreover, specific language impairment (SLI) has been reported for several individual children in large DGS cohorts (Solot et al., 2000) or smaller case studies (Goorhuis-Brouwer, Dikkers, Robinson, &
Kerstjens-Frederikse, 2003). SLI is a term applied for children whose speech and language is substantially below age level for no apparent reason, that is, in the absence of neurological damage, impaired sensorimotor abilities, and so on (i.e. with normal intelligence levels, hearing, vision, etc.).
To our knowledge, our report is the first to describe in detail the linguistic manifestations of the language deficit associated with this particular genetic syndrome for Greek, and in the context of bilectalism (Rowe & Grohmann, 2013). Bilectalism is used here to characterise the situation in Cyprus in which children of Greek Cypriot parents, with Cypriot Greek-speaking family and friends, grow up, yet get exposed to Standard Modern Greek from an early age; first through media such as TV cartoons, later through public schooling starting in nursery and kindergarten, becoming gradually more systematic in primary school. In the absence of a separate Cypriot Greek orthographic system, Greek can only be taught through the medium of the standard variety in order to teach children how to read and write. We take this to be the standard path of language development by Greek Cypriot children, as relevant for our study.
Method Aims
A core area of investigation will be the DGS participant’s abilities in structural language, that is, his morphosyntactic abilities and performance in more complex language. Our testing battery contains several measures for structural language, ranging from morphosyntactic properties (agreement relations) and phenomena (object clitic production) to structurally complex clauses (including subordinates and relatives). But the entire testing battery goes well beyond structural language. As the first research on language abilities in DGS for (Cypriot) Greek, we take a broader angle.
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The purpose of the present study is then to profile the language abilities of one male child (PI) with DGS and compare his performance to that reported for children of the same chronological age with typical language development and with SLI across a battery of linguistic tests. The aims of the study are three-fold:
1. to investigate PI’s receptive and expressive language abilities, with an emphasis on structural language performance;
2. to compare PI’s language performance across all measures with that of typically developing children of the same chronological age;
3. to compare PI’s language performance across all measures with that of children of the same chronological age diagnosed with SLI.
Participant
Our participant, PI, was a preschool boy who was 5;11 (years;months) when the study began and enrolled in the preschool education program of a public school in Nicosia, Cyprus. He was not receiving special education services.
He was diagnosed with DiGeorge syndrome using the fluorescence in situ hybridisation test (FISH) by the Genetics Clinic of the Makarios Hospital in Nicosia. This test shows whether the region of chromosome 22 is present. If only one copy of chromosome 22 ‘lights up’ with fluorescent DNA dye, rather than both copies, the test is positive for 22q11 deletion. Hearing was tested by the Audiology Clinic of the Makarios Hospital and reported to be within normal limits. Also, the hospital reported no positive assessment of autism spectrum disorder symptoms or any other psychiatric condition.
He was born from healthy, unrelated parents who are both highly educated with university degrees, in an allied health profession (mother) and information technology (father). PI has a healthy brother who is older by three years.
An oral-peripheral motor examination administered by a certified speech and language therapist (first author) revealed no structural abnormalities of the speech mechanism. At the time of the study, PI was receiving private speech therapy for voice quality (e.g., hypernasality) and mild misarticulations. He presented hoarseness and reduced vocal volume but generally intelligible speech during the time of the study. Testing across all measures was conducted over a three-month period.
Comparative groups
For our comparison with PI, a total of 19 bilectal Greek Cypriot preschool children participated in this study. For selection purposes, we considered as bilectal those children whose parents are both Greek Cypriots, who were born and raised in Cyprus, and who did not spend any large amount of time outside the island, including Greece. We did not control any more, specifically for balanced input or age of exposure to Cypriot Greek and Standard Modern Greek, but assumed the standard path of language development laid out above (see Grohmann & Kambanaros, to appear for more). The children were divided into two groups, one group including children with SLI of the same chronological age as PI and a control group, namely a chronological age-matched group.
All children came from the Limassol district and the majority attended public pre-primary or primary schools. Parental consent forms and an information letter that explained the purpose of the study were distributed, and only children whose parents gave written consent participated in the study. The consent form provided additional information such as demographics, the education level of each of the parents, and the parents’ occupation (see Theodorou, 2013 for participant details). The criteria that restricted individual participation included: (i) a known history of neurological, emotional, developmental, or behavioural problems; (ii) hearing and vision not adequate for test purposes after school screening at the beginning of the school year; (iii) non-verbal performance not in the broad range of normal; (iv) gross motor difficulties; and (v) low socio-economic status. All the above information was obtained either from the speech-language therapists and teachers or from the children’s parents. The children were divided into two comparative groups, a group with typical language development (TLD) and a group of children with SLI.
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Nine children with SLI (7 boys and 2 girls), aged between 4;11 and 5;11 with a mean age of 5;6 (SD 0;3), served as the language-impaired comparative group. Children were diagnosed with SLI by certified speech and language therapists based on case history information, informal testing (of comprehension and production abilities), analysis of spontaneous language samples, and clinical observation. Children with SLI included in the study were receiving speech and language therapy services by practitioners in private settings.
TLD group
Ten children with TLD (6 boys and 4 girls), aged between 4;5 and 6;6 with a mean age of 5;8 (SD 0;6), served as the chronological age-matched group. According to the classroom teacher and parent report, each participant in the control groups was typically developing in all respects. No child was previously referred to or had received treatment by a speech and language therapist.
Socio-economic status
All children came from families with a medium to high socio-economic status, as measured by mothers’ education level using the European Social Survey (2010) database. We compared PI’s mother’s education level (undergraduate degree from university) to the education levels of the mothers of the other two groups. Her education level did not differ from the TLD group mothers’ (t(9)
= –.52, p = .62), but it did so from the SLI group (t(8) = 2.47, p < .05), whose mother’s education levels had a lower mean than PI’s mother’s.
Nonverbal IQ
Prior to the study proper, all children were tested on the Raven’s Coloured Progressive Matrices (Raven, Raven, & Court, 2000), following the Greek norms of Sideridis, Antoniou, Mouzaki, &
Simos (2015). This requirement was satisfied for each child separately.
Materials and procedures
All language measures were administered to PI and the two groups of children, those with a clinical identification of language impairment and the typically developing ones. The tests are described in detail below.
A. Diagnostic Verbal IQ Test (DVIQ)
Children’s global language abilities were measured using the Diagnostic Verbal IQ Test (Stavrakaki
& Tsimpli, 2000), modified for Cypriot Greek (Theodorou, 2013). This test is used by language researchers and clinicians to assess language abilities for Greek-speaking children; while it is not yet standardised, though, it is in the process of undergoing standardisation in Greece. The DVIQ has five subtests: expressive vocabulary, comprehension of morphosyntax, production of morphosyntax, comprehension of metalinguistic concepts, and sentence repetition. The production of morphosyntax subtest includes such diverse grammatical properties and markers as nominal and verbal suffixes, object clitics, articles, agreement relations, and relative clauses among others.
Each child was tested individually on all subtests, which involved naming and showing pictures as well as completing and repeating sentences. Children’s responses were recorded on the answer sheets, and later analysed and scored. Each correct response received 1 point, with the exception of the sentence repetition subtest, which was scored according to the number of errors in each repetition (maximum score of 3 points correct for each sentence). The original DVIQ has been used in published studies for the identification of children with SLI in Greece (Mastropavlou, Petinou, & Tsimpli, 2011) and Cyprus (Petinou & Okalidou, 2006; Mastropavlou et al., 2011); the Cypriot Greek-adapted version has also been tested widely in Cyprus by our research team for which published studies include Kambanaros, Grohmann, Michaelides, & Theodorou (2013; 2014), among others.
B. The Bus Story Test (BST)
A topic-centred narrative, the Bus Story Test (Renfrew, 1997) is used widely by speech and language therapists to assess narrative abilities in children ranging from 3 to 8 years of age. It is translated into
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Greek and also used in Greece as a non-standardised measure. For this study, the Greek translation of the BST was used (with minor changes in phonology and morphology adapted to Cypriot Greek), since Greek Cypriot children are used to hearing stories in Standard Modern Greek rather than in Cypriot Greek from their preschool years.
The experimenter told each child the story individually while the child looked at the picture strips illustrating the story. Afterwards, the child was requested to retell the story as close to the original as possible. Test administration was around 10 minutes. The narrative samples were transcribed and divided into sentences (t-units). Children’s narrative productions were each evaluated with respect to five descriptors, three from the BST manual and two additional ones developed for our research purposes:
1. Information (Renfrew, 1997): The number of relevant information pieces were tallied following the BST manual, where ‘essential’ information gets two points and ‘subsidiary’ information gets one point; the Information score is the total number of points accumulated.
2. Subordinates Clauses (Renfrew, 1997): All subordinate clauses were identified and counted for a total score, as per BST manual.
3. A5LS: The mean length of the five longest sentences was computed.
4. MLU-word: In the absence of normative data for mean length of utterance (MLU) in Cypriot Greek, it was calculated based on words for each narrative (MLU-word); all words were added up and the sum was divided by sentences produced (MLU-word was chosen, since there is no study to support the use of a morpheme-based MLU in any variety of Modern Greek).
5. T-units (Renfrew, 1997): The total number of sentences produced was added up, as suggested in the BST manual.
C. Expressive Vocabulary test (EVT)
In order to assess naming abilities, the Expressive Vocabulary Test (Vogindroukas, Protopapas, &
Sideris, 2009) was administered. The EVT contains 50 concrete black-and-white pictures for naming.
It is standardised in Greece and has norms for Standard Modern Greek. Because of the differences between the standard language and the dialect, 11 items have alternative words in Cypriot Greek (10 lexical alternatives and 1 phonological alternative); they were considered acceptable responses.
Children were asked to name the object in the picture. Responses were recorded on the answer sheet and then scored as correct or incorrect on a word-by-word basis.
D. Peabody Picture Vocabulary Test (PPVT)
In order to assess receptive vocabulary skills, the Greek version of the Peabody Picture Vocabulary Test (Dunn & Dunn, 1981, adapted to Standard Modern Greek by Simos, Kasselimis, & Mouzaki, 2011), developed for research purposes, was used. The PPVT measures receptive vocabulary at the single word level.
The Greek version of the test consists of 228 items, equally distributed across 19 item-sets. Each set contains 12 items of increasing difficulty. The examiner presented a quadrant of four numbered pictures and asked the child to point to or say the number of the picture of the spoken word.
E. Clitics-in-Island Test (CIT)
The COST Action A33 Clitics-in-Islands Test (Varlokosta, Belletti, Costa, Friedmann, Gavarró, Grohmann, Guasti, Tuller, et al., 2015), a testing tool designed to elicit clitic production, was used.
The CIT is a production task for 3rd person singular accusative object clitics in which the target- elicited clitic was embedded within a because-clause (a so-called syntactic island):
I mama xtenizi ti korua t∫e i korua en omorfi. Jati i korua en omorfi? I korua en omorfi jati i mama tis… [xtenizi tin-CL].
“Mommy is combing the girl and the girl is beautiful. Why is the girl beautiful? The girl is beautiful because her mommy… [combs her-CL].”
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The CIT involved a total of 19 items; 12 target structures (i.e. test items) after two warm-ups, plus five unrelated fillers. All target structures were indicative declarative clauses formed around a transitive verb. All participating children were shown a coloured sketch picture on a laptop screen, depicting the situation that was described by the experimenter. Figure 1 illustrates for the above example.
Figure 1. Test item #2 (example)
Participants heard the description of each picture that the experimenter provided and then had to complete the because-clause in which the use of a clitic was expected. The ideal response would be a verb-clitic sequence (such as xtenizi tin ‘combs her’ in the above example), but some participants started with because on their own, others filled in right after the experimenter’s prompt of because.
The experiments were not audio- or video-taped, but answers were recorded by the experimenter on a score sheet during the session.
Structural language probes
We consider structural language probes to be those that tap into morphosyntactic abilities and language complexity. For our purposes, the comprehension and production of morphosyntax subtests of the DVIQ, the sentence repetition subtest of the DVIQ, number of subordinate clauses produced on the BST, and performance on the CIT will serve as measures of structural language complexity for our analyses in this research.
Scoring and analysis
For all tests, an accuracy score was calculated by summing up the number of correct responses. For all sub-categories of the DVIQ, except sentence repetition, a single point was given for every correct response and no points for every incorrect one. For sentence repetition, 3 points were given for every correct response, 2 points for every response with one error, 1 point for every response with 2 errors, and no points for responses with 3 or more errors.
Results
The main statistical analysis used was the Crawford–Howell t-test (Crawford & Howell, 1998), a method developed in neuropsychology for the comparison of single cases with control groups (with small sample numbers). Using this method, PI’s accuracy scores were compared to the TLD and SLI groups using a one-tailed t-test. The results are reported in Table 1 (where Table 1a includes correct scores as percentage points and Table 1b as standardised raw scores).
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Table 1a. Percentage correct (DVIQ, PPVT, EVT, CIT) for PI (DGS) in comparison to the TLD group and the SLI group
Test Sub-test Score
DGS TLD (SD) SLI (SD)
DVIQ
Vocabulary 70.5% 84.8% (8.1) 62.1% (10.4)
Production: Morphosyntax 33.3% 73.3% (7.8) 51.4% (10.1) Comprehension: Metalinguistic concepts 68.0% 79.6% (7.2) 72.0% (2.5) Comprehension: Morphosyntax 51.6% 81.9% (8.4) 79.2% (2.6)
Sentence repetition 72.9% 94.8% (5.2) 85.2% (1.7)
Total DVIQ Score 61.9% 82.1% (4.9) 73.6% (1.6)
PPVT 16% 30.1% (5.5) 25.8% (7.8)
EVT 50% 66.6% (10.3) 43.4% (5.5)
CIT 75% 96.7% (10.5) 91.7% (8.3)
Key: DVIQ=Diagnostic Verbal IQ Test, PPVT=Peabody Picture Vocabulary Test, EVT=Expressive Vocabulary Test, CIT=Clitics-in-Islands Test, DGS=DiGeorge syndrome, TLD=typical language development, SLI=specific
language impairment, SD=standard deviation
Table 1b: Raw scores (BST) and standard scores (RCPM) for PI (DGS) in comparison to the TLD group and the SLI group
Test Sub-test Score
DGS TLD (SD) SLI (SD)
BST
Information 17 35.8 (11.5) 21.8 (8.9)
A5SL 5.4 8.44 (2.1) 5.4 (.8)
Subordinate clauses 1 7.8 (4.1) 1.7 (1.5)
T-units 8 20.6 (3.9) 15.6 (3.8)
MLU–word 4.6 4.7 (1.2) 3.4 (.7)
RCPM 69 90 (12.5) 100.6 (12.9)
Key: BST=Bus Story Test, RCPM=Raven’s Coloured Progressive Matrices, DGS=DiGeorge syndrome, TLD=typical language development, SLI=specific language impairment, SD=standard deviation Nonverbal IQ
There were no statistically significant differences in nonverbal IQ between the SLI and TLD groups (Mann–Whitney U = 25.5, n1 = 10, n2 = 9, p = .11 two-tailed). When PI’s was compared to the mean performance of each group, there was no significant difference from the TLD group (t(9) = –1.61, p = .07), but his nonverbal IQ was significantly lower than that of the SLI group (t(8) = –2.29, p < .05).
DVIQ
PI’s comparison to the TLD group revealed that he performed significantly lower on three subtests of the DVIQ: (i) in the production of morphosyntax (t(9) = –4.9, p < .001); (ii) in the comprehension of morphosyntax (t(9) = –3.46, p < .01), and (iii) in the sentence repetition subtest (t(9) = –3.99, p < .01).
PI showed no significant difference from the TLD peers on the remaining two subtests of the DVIQ, namely comprehension of metalinguistic concepts (t(9) = –1.55, p = .08) and expressive vocabulary
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(t(9) = –1.71, p = .06). Overall, his total DVIQ score was significantly lower than that of his TLD peers (t(9) = –4.69, p < .01).
When PI’s performance was compared to that of the SLI group, he showed a significantly lower performance on two DVIQ subtests: (i) comprehension of morphosyntax (t(8) = –2.12, p < .05) and (ii) sentence repetition (t(8) = –2.26, p < .05). There was no significant difference between PI and the SLI group on the remaining DVIQ subtests, expressive vocabulary (t(8) = .75, p = .24), comprehension of metalinguistic concepts (t(8) = –0.25, p = .41), and production of morphosyntax (t(8) = –1.71, p = .06).
Overall, his total DVIQ score was not significantly different from the SLI group (t(8) = –1.64, p = .07).
Figure 2 shows PI’s performance in comparison to the TLD and SLI groups on the subtests and total score on the DVIQ test.
Key: MS=morphosyntax, SR=sentence repetition,
TLD=typical language development, SLI=specific language impairment, DGS=DiGeorge syndrome Figure 2. Performance of PI (DGS) in comparison to the TLD group and the SLI group on the five
different subtests of the DVIQ BST
When PI’s performance was compared to the TLD group on the BST, he showed a significantly lower performance only on the number of sentences (t-units) produced (t(9) = –3.09, p < .01). There was no significant difference between PI and the TLD group for Information (t(9) = –1.55, p = .08), A5LS (t(9)
= –1.37, p = .1), number of subordinate clauses produced (t(9) = –1.58, p = .07), and MLU-word (t(9) = –.06, p = .48).
When compared to the SLI group, PI also only showed a significantly lower performance for number of sentences (t-units) produced (t(8) = –1.91, p < .05). There were no significant differences between PI and the SLI group performance for Information (t(8) = –.51, p = .31), A5LS (t(8) = 0, p = .5), number of subordinate clauses produced (t(8) = –.42, p = .34), and MLU–word (t(8) = 1.64, p = .07).
Figure 3 shows PI’s performance compared to the TLD and SLI groups on the number of sentences (t- units) produced.