Etiology of Mental Retardation in Children Referred to a Tertiary Care Center: A Prospective Study

Karnebeek, Clara van; Scheper, Frederike Y.; Abeling, N. G. G. M.; Alders, Mariëlle; Barth, Peter; Hoovers, J. M. N.; Koevoets, Cindy; Wanders, Ronald J. A.; Hennekam, Raoul C. M.

doi:10.1352/0895-8017(2005)110[253:eomric]2.0.co;2

Cited by 106 publications

(83 citation statements)

References 28 publications

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“…This association was not found in an earlier study. 30 Intrauterine infections may be difficult to confirm in older children and some genetic syndromes may not manifest all the dysmorphic features till a later age. Severity of intellectual disability or GDD did not influence the diagnostic yield in our study, a finding consistent with previous studies.…”

Section: Discussionmentioning

confidence: 99%

“…Severity of intellectual disability or GDD did not influence the diagnostic yield in our study, a finding consistent with previous studies. 3,30 We found that the combination of clinical history and examination to be the most useful tool in arriving at a diagnosis. Even though we observed strict criteria for final diagnosis incorporating both clinical features and investigations in almost three quarters of the patients, clinical history and examination gave important clues suggestive of other conditions.…”

Section: Discussionmentioning

confidence: 99%

“…Karnebeek et al have also reported on the high yield of the neurological examination. 30 One third of their patients could be diagnosed on the basis of history and physical examination only, in another third the history and examination provided important clues to the diagnosis, and the remaining third could be diagnosed through investigations only.…”

Section: Discussionmentioning

confidence: 99%

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Aetiology of intellectual disability in paediatric outpatients in Northern India

Jauhari

Boggula

Bhave

et al. 2010

Developmental Medicine &Amp; Child Neurology

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GDD Global developmental delay OPD Outpatients departmentAIM To study the aetiology of intellectual disability in patients presenting to hospital and the diagnostic yield of a standardized examination.METHOD Over a 1-year period, the first three children presenting to the paediatric outpatients department (OPD) on 2 selected weekdays with developmental delay, suspected intellectual disability, or school failure were enrolled for study if they satisfied standard definitions of global developmental delay (GDD), or intellectual disability as tested by scales for Indian children: Developmental Assessment for Indian Infants, Binet Karnat Test, and the Vineland Social Maturity Scale (Malin's Adaptation). Detailed history, and physical and neurological examinations were recorded. An algorithmic approach to investigations was followed. Also, neuroimaging, thyroid function, electroencephalograph, karyotyping, and studies for fragile-X syndrome were conducted. Aetiological diagnosis was considered established only if clinical features were supported by investigations. Clinical features associated with a successful aetiological diagnosis were computed.RESULTS A total of 122 children were enrolled in a cross-sectional analytic study (mean age 43.5mo [SD 40.66]; 84 males, 38 females). Of these, a definite aetiology could be assigned in 66 children (54.1%); 17 prenatal, 38 perinatal ⁄ neonatal, and 11 postneonatal. Factors associated with reaching a definite diagnosis included younger age at presentation, presence of seizures, microcephaly, adverse neonatal events, and abnormal motor signs. Clinical history and examination gave important clues to the aetiology in 89 (72.9%) patients. Neuroimaging was abnormal in 91 out of 114 children, with aetiological findings in 48 children.INTERPRETATION Perinatal ⁄ neonatal causes predominate as the cause of GDD or intellectual disability in India. The study highlights that a large majority of cases seen here were preventable.Intellectual disability is characterized by significant limitations both in intellectual functioning and in adaptive behaviour as expressed in conceptual, social, and practical adaptive skills, which originate before age 18. 1 The term intellectual disability is used above the age of 5 years when standard psychometric testing becomes valid and reliable, while below this age the term global developmental delay (GDD) is used. 2 Intellectual disability is a disorder of varied aetiology broadly classifiable as having prenatal, perinatal, and postnatal causes. Aetiological yield of intellectual disability varies with its severity, the population and country studied, extent of diagnostic examination, and era in which the study was conducted. Overall, aetiological diagnosis is made in slightly over half the patients. 3,4 The reported frequencies of aetiological categories of intellectual disability are remarkably variable, with exogenous and endogenous (genetic) causes both ranging roughly between 17% and 47%. 5 Again, variations may be explained by differences in setting,...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Aetiology of intellectual disability in paediatric outpatients in Northern India

Jauhari

Boggula

Bhave

et al. 2010

Developmental Medicine &Amp; Child Neurology

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“…15 Genetic causes account for 17.4-47.1% of cases, with reported frequencies also varying on the basis of the different techniques used for analysis. 15,16 Several years ago, microarray platforms were used for the first time in clinical genetics, showing that abnormalities in genomic copy number account for about 10-15% of patients affected by MR, especially when it is associated with multiple congenital anomalies (MCA) and/or dysmorphism. 17 Microarrays represent a robust and high-resolution method of analysis.…”

Section: Introductionmentioning

confidence: 99%

High-resolution SNP arrays in mental retardation diagnostics: how much do we gain?

Bernardini¹,

Alesi

Loddo

et al. 2009

Eur J Hum Genet

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We used Affymetrix 6.0 GeneChip SNP arrays to characterize copy number variations (CNVs) in a cohort of 70 patients previously characterized on lower-density oligonucleotide arrays affected by idiopathic mental retardation and dysmorphic features. The SNP array platform includes B900 000 SNP probes and 900 000 non-SNP oligonucleotide probes at an average distance of 0.7 Kb, which facilitates coverage of the whole genome, including coding and noncoding regions. The high density of probes is critical for detecting small CNVs, but it can lead to data interpretation problems. To reduce the number of false positives, parameters were set to consider only imbalances 475 Kb encompassing at least 80 probe sets. The higher resolution of the SNP array platform confirmed the increased ability to detect small CNVs, although more than 80% of these CNVs overlapped to copy number 'neutral' polymorphism regions and 4.4% of them did not contain known genes. In our cohort of 70 patients, of the 51 previously evaluated as 'normal' on the Agilent 44K array, the SNP array platform disclosed six additional CNV changes, including three in three patients, which may be pathogenic. This suggests that about 6% of individuals classified as 'normal' using the lower-density oligonucleotide array could be found to be affected by a genomic disorder when evaluated with the higher-density microarray platforms.

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“…2 As part of a large collaborative project to identify genes involved in autosomal recessive MR, 3 we performed linkage analysis in an Iranian family with three affected siblings who suffered from an apparently novel syndromic form of MR associated with cataract, coloboma and kyphosis. Here, we report on the clinical details of the patients and the identification of a gene locus in the pericentromeric region of chromosome 4.…”

Section: Introductionmentioning

confidence: 99%

An autosomal recessive syndrome of severe mental retardation, cataract, coloboma and kyphosis maps to the pericentromeric region of chromosome 4

et al. 2008

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We report on three siblings with a novel mental retardation (MR) syndrome who were born to distantly related Iranian parents. The clinical problems comprised severe MR, cataracts with onset in late adolescence, kyphosis, contractures of large joints, bulbous nose with broad nasal bridge, and thick lips. Two patients also had uni-or bilateral iris coloboma. Linkage analysis revealed a single 10.4 Mb interval of homozygosity with significant LOD score in the pericentromeric region of chromosome 4 flanked by SNPs rs728293 (4p12) and rs1105434 (4q12). This interval contains more than 40 genes, none of which has been implicated in MR so far. The identification of the causative gene defect for this syndrome will provide new insights into the development of the brain and the eye.

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Etiology of Mental Retardation in Children Referred to a Tertiary Care Center: A Prospective Study

Cited by 106 publications

References 28 publications

Aetiology of intellectual disability in paediatric outpatients in Northern India

Aetiology of intellectual disability in paediatric outpatients in Northern India

High-resolution SNP arrays in mental retardation diagnostics: how much do we gain?

An autosomal recessive syndrome of severe mental retardation, cataract, coloboma and kyphosis maps to the pericentromeric region of chromosome 4

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