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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two patients with monosomy for the distal portion of the short arm of chromosome 3 are described. Chromosome analysis on prometaphase cells demonstrated a karyotype of 46,XX,del(3) (p25.3) in one patient and 46,XX,r(3)(p26.1q29) in the other. The former patient showed characteristic clinical manifestations of the 3p- syndrome, including growth failure, mental retardation, microcephaly with a flat occiput, triangular face, synophrys, blepharoptosis, hypertelorism, broad and flat nose, long philtrum, down-turned mouth, micrognathia, apparently lowset and malformed ears, fingers abnormalities, and deafness. The latter patient had a nonspecific phenotype with mental retardation, growth failure and microcephaly. Karyotype-phenotype comparisons in the present cases and 16 previously reported cases with deficiency of the distal portion of 3p suggests that deficiency of the 3p25.3 band is critical to produce the main clinical manifestations of the del(3p) syndrome.
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PMID:Loss of the 3p25.3 band is critical in the manifestation of del(3p) syndrome: karyotype-phenotype correlation in cases with deficiency of the distal portion of the short arm of chromosome 3. 217 18

A male child with mental retardation and poor growth was found to have a 46,XY,r3 (p26 leads to q29) karyotype in 92% of his peripheral lymphocytes and 90% of his cultured fibroblasts. Comparison of this patient's dysmorphic features with previously reported cases of ring 3 or deletion 3p suggests a clinical syndrome derived mainly from deletion of 3p26 leads to pter. The syndrome consists of mental retardation, pre- and postnatal growth retardation, microcephaly, hypertonia, digital anomalies, and a characteristic facies with ptosis, epicanthal folds, broad nasal root, down-turned corners of the mouth, and dysplastic ears.
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PMID:The phenotype of ring chromosome 3. 715 48

Molecular genetic analysis of five cases of 3p- syndrome (del(3)(qter-->p25:)) was performed to investigate the relationship between the molecular pathology and clinical phenotype. Fluorescence in situ hybridization studies and analysis of polymorphic DNA markers from chromosome 3p25-p26 demonstrated that all four informative cases had distal deletions. However, the extent of the deletion was variable: in two patients with the most extensive deletions the deletion breakpoint mapped between RAF1 and D3S1250, in one patient the deletion breakpoint was between D3S1250 and D3S601, and in two patients the deletion commenced telomeric to D3S601 (and telomeric to D3S1317 in one of these). All five patients displayed the classical features of 3p- syndrome (mental retardation, growth retardation, microcephaly, ptosis and micrognathia) demonstrating that loss of sequences centromeric to D3S1317 is not required for expression of the characteristic 3p- syndrome phenotype. The three patients with the most extensive deletions had cardiac septal defects suggesting that a gene involved in normal cardiac development is contained in the interval D3S1250 and D3S18. The PMCA2 gene is contained within this region and deletion of this gene may cause congenital heart defects. At least three patients were deleted for the von Hippel-Lindau (VHL) disease gene although none had yet developed evidence of VHL disease. We conclude that molecular analysis of 3p- syndrome patients enhances the management of affected patients by identifying those at risk for VHL disease, and can be used to elucidate the critical regions for the 3p- syndrome phenotype.
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PMID:Molecular genetic analysis of the 3p- syndrome. 795 Dec 34

Distal deletion of chromosome 3p25-pter (3p- syndrome) produces a distinct clinical syndrome characterised by low birth weight, mental retardation, telecanthus, ptosis, and micrognathia. Congenital heart disease (CHD), typically atrioventricular septal defect (AVSD), occurs in about a third of patients. In total, approximately 25 cases of 3p- syndrome have been reported world wide. We previously analysed five cases and showed that (1) the 3p25-pter deletions were variable and (2) the presence of CHD correlated with the proximal extent of the deletion, mapping a CHD gene centromeric to D3S18. To define the molecular pathology of the 3p- syndrome further, we have now proceeded to analyse the deletion region in a total of 10 patients (five with CHD), using a combination of FISH analysis and polymorphic markers, for up to 21 loci from 3p25-p26. These additional investigations further supported the location of an AVSD locus within 3p25 and refined its localisation. Thus, the critical region was reduced to an interval between D3S1263 and D3S3594. Candidate 3p25 CHD genes, such as PMCA2 (ATP2B2), fibulin 2, TIMP4, and Sec13R, were shown to map outside the target interval. Additionally, the critical region for the phenotypic features of the 3p- phenotype was mapped to D3S1317 to D3S17 (19-21 cM). These findings will accelerate the identification of the 3p25 CHD susceptibility locus and facilitate investigations of the role of this locus in non-syndromic AVSDs, which are a common form of familial and isolated CHD.
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PMID:Detailed mapping of a congenital heart disease gene in chromosome 3p25. 1092 84

Whereas in the great majority of autosomal duplications/deficiencies a clinically recognizable dysmorphic syndrome is present, distal 3p duplication is not associated with major dysmorphic signs. We present the clinical data and molecular cytogenetic findings in two non-related patients. Diagnosis was made in a female child at the age of 5 months because of psychomotor retardation and slight dysmorphism. She also presented hydronefrosis and develops no speech at the age of almost 4 years. Her partial trisomy is the result of an inverted duplication 3p22-->3pter (dup(3)(pter-->p26::p22(p26::p26-->ter)). An adult woman was diagnosed at the of 80 years only on the basis of mental retardation and poor speech development, but without evident dysmorphism. In this patient the partial 3p trisomy is the unbalanced product of a 3p/17p translocation: t(3;7)(p253;p133).
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PMID:Partial distal trisomy 3p. A partial autosomal trisomy without major dysmorphic features. 1133 82

Deletion 3p syndrome is associated with characteristic facial features, growth failure, and mental retardation. Typically, individuals with deletion 3p syndrome have terminal deletions that result in loss of material from 3p25 to 3pter. We present a child with a clinical phenotype consistent with deletion 3p syndrome (ptosis, microcephaly, growth retardation, and developmental delay) and a subtle interstitial deletion in the distal portion of the short arm of chromosome 3, del(3)(p25.3p26.2). Fluorescence in situ hybridization (FISH) studies using 3p subtelomeric probes confirmed the terminal region of chromosome 3 was present. Sequence tagged sites (STS)-linked BAC clones mapping to chromosomal region 3p25-p26 were used to characterize the interstitial deletion by FISH. The results indicate the deletion is within a region of approximately 4.5 Mb between STS markers D3S3630 and D3S1304. This interstitial deletion lies within all previously reported terminal deletions in deletion 3p syndrome individuals, and represents the smallest reported deletion associated with deletion 3p syndrome. Characterization of the deletion may help identify genes important to growth and development that contribute to the deletion 3p syndrome phenotype when present in a hemizygous state.
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PMID:Molecular cytogenetic characterization of a subtle interstitial del(3)(p25.3p26.2) in a patient with deletion 3p syndrome. 1197 62

Investigation of MR patients with 3p aberrations led to the identification of the translocation breakpoint in intron five of the neural Cell Adhesion L1-Like (CALL or CHL1) gene in a man with non-specific mental retardation and 46,Y, t(X;3)(p22.1;p26.3). The Xp breakpoint does not seem to affect a known or predicted gene. Moreover, a fusion transcript with the CALL gene could not be detected and no mutations were identified on the second allele. CALL is highly expressed in the central and peripheral nervous system, like the mouse ortholog 'close homolog to L1' (Chl1). Chl1 expression levels in the hippocampus of Chl1(+/-) mice were half of those obtained in wild-type littermates, reflecting a gene dosage effect. Timm staining and synaptophysin immunohistochemistry of the hippocampus showed focal groups of ectopic mossy fiber synapses in the lateral CA3 region, outside the trajectory of the infra-pyramidal mossy fiber bundle in Chl1(-/-) and Chl1(+/-) mice. Behavioral assessment demonstrated mild alterations in the Chl1(-/-) animals. In the probe trial of the Morris Water Maze test, Chl1(-/-) mice displayed an altered exploratory pattern. In addition, these mice were significantly more sociable and less aggressive as demonstrated in social exploration tests. The Chl1(+/-) mice showed a phenotypic spectrum ranging from wild-type to knockout behavior. We hypothesize that a 50% reduction of CALL expression in the developing brain results in cognitive deficits. This suggests that the CALL gene at 3p26.3 is a prime candidate for an autosomal form of mental retardation. So far, mutation analysis of the CALL gene in patients with non-specific MR did not reveal any disease-associated mutations.
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PMID:CALL interrupted in a patient with non-specific mental retardation: gene dosage-dependent alteration of murine brain development and behavior. 1281 75

Autism is a complex, behaviorally defined, static disorder of the immature brain that is of great concern to the practicing pediatrician because of an astonishing 556% reported increase in pediatric prevalence between 1991 and 1997, to a prevalence higher than that of spina bifida, cancer, or Down syndrome. This jump is probably attributable to heightened awareness and changing diagnostic criteria rather than to new environmental influences. Autism is not a disease but a syndrome with multiple nongenetic and genetic causes. By autism (the autistic spectrum disorders [ASDs]), we mean the wide spectrum of developmental disorders characterized by impairments in 3 behavioral domains: 1) social interaction; 2) language, communication, and imaginative play; and 3) range of interests and activities. Autism corresponds in this article to pervasive developmental disorder (PDD) of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition and International Classification of Diseases, Tenth Revision. Except for Rett syndrome--attributable in most affected individuals to mutations of the methyl-CpG-binding protein 2 (MeCP2) gene--the other PDD subtypes (autistic disorder, Asperger disorder, disintegrative disorder, and PDD Not Otherwise Specified [PDD-NOS]) are not linked to any particular genetic or nongenetic cause. Review of 2 major textbooks on autism and of papers published between 1961 and 2003 yields convincing evidence for multiple interacting genetic factors as the main causative determinants of autism. Epidemiologic studies indicate that environmental factors such as toxic exposures, teratogens, perinatal insults, and prenatal infections such as rubella and cytomegalovirus account for few cases. These studies fail to confirm that immunizations with the measles-mumps-rubella vaccine are responsible for the surge in autism. Epilepsy, the medical condition most highly associated with autism, has equally complex genetic/nongenetic (but mostly unknown) causes. Autism is frequent in tuberous sclerosis complex and fragile X syndrome, but these 2 disorders account for but a small minority of cases. Currently, diagnosable medical conditions, cytogenetic abnormalities, and single-gene defects (eg, tuberous sclerosis complex, fragile X syndrome, and other rare diseases) together account for <10% of cases. There is convincing evidence that "idiopathic" autism is a heritable disorder. Epidemiologic studies report an ASD prevalence of approximately 3 to 6/1000, with a male to female ratio of 3:1. This skewed ratio remains unexplained: despite the contribution of a few well characterized X-linked disorders, male-to-male transmission in a number of families rules out X-linkage as the prevailing mode of inheritance. The recurrence rate in siblings of affected children is approximately 2% to 8%, much higher than the prevalence rate in the general population but much lower than in single-gene diseases. Twin studies reported 60% concordance for classic autism in monozygotic (MZ) twins versus 0 in dizygotic (DZ) twins, the higher MZ concordance attesting to genetic inheritance as the predominant causative agent. Reevaluation for a broader autistic phenotype that included communication and social disorders increased concordance remarkably from 60% to 92% in MZ twins and from 0% to 10% in DZ pairs. This suggests that interactions between multiple genes cause "idiopathic" autism but that epigenetic factors and exposure to environmental modifiers may contribute to variable expression of autism-related traits. The identity and number of genes involved remain unknown. The wide phenotypic variability of the ASDs likely reflects the interaction of multiple genes within an individual's genome and the existence of distinct genes and gene combinations among those affected. There are 3 main approaches to identifying genetic loci, chromosomal regions likely to contain relevant genes: 1) whole genome screens, searching for linkage of autism to shared genetic markers in populations of multiplex families (families with >1 affected family member; 2) cytogenetic studies that may guide molecular studies by pointing to relevant inherited or de novo chromosomal abnormalities in affected individuals and their families; and 3) evaluation of candidate genes known to affect brain development in these significantly linked regions or, alternatively, linkage of candidate genes selected a priori because of their presumptive contribution to the pathogenesis of autism. Data from whole-genome screens in multiplex families suggest interactions of at least 10 genes in the causation of autism. Thus far, a putative speech and language region at 7q31-q33 seems most strongly linked to autism, with linkages to multiple other loci under investigation. Cytogenetic abnormalities at the 15q11-q13 locus are fairly frequent in people with autism, and a "chromosome 15 phenotype" was described in individuals with chromosome 15 duplications. Among other candidate genes are the FOXP2, RAY1/ST7, IMMP2L, and RELN genes at 7q22-q33 and the GABA(A) receptor subunit and UBE3A genes on chromosome 15q11-q13. Variant alleles of the serotonin transporter gene (5-HTT) on 17q11-q12 are more frequent in individuals with autism than in nonautistic populations. In addition, animal models and linkage data from genome screens implicate the oxytocin receptor at 3p25-p26. Most pediatricians will have 1 or more children with this disorder in their practices. They must diagnose ASD expeditiously because early intervention increases its effectiveness. Children with dysmorphic features, congenital anomalies, mental retardation, or family members with developmental disorders are those most likely to benefit from extensive medical testing and genetic consultation. The yield of testing is much less in high-functioning children with a normal appearance and IQ and moderate social and language impairments. Genetic counseling justifies testing, but until autism genes are identified and their functions are understood, prenatal diagnosis will exist only for the rare cases ascribable to single-gene defects or overt chromosomal abnormalities. Parents who wish to have more children must be told of their increased statistical risk. It is crucial for pediatricians to try to involve families with multiple affected members in formal research projects, as family studies are key to unraveling the causes and pathogenesis of autism. Parents need to understand that they and their affected children are the only available sources for identifying and studying the elusive genes responsible for autism. Future clinically useful insights and potential medications depend on identifying these genes and elucidating the influences of their products on brain development and physiology.
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PMID:The genetics of autism. 1512 91

A male teenager formerly found to have a 46,XY,del(3)(p26)de novo karyotype was restudied. At the age of 14(8/12) yr, he attends the last grade of middle school and was a cooperating teenager with slender habitus, severe myopia, prominent nose, sacral dimples, pubertal stage Tanner III, and multiple surgical scars. Neuropsychological studies revealed a full scale IQ of 95 with slow performance (WISC-IV Spanish test) as well as an internalizing behavioral profile, poor social skills, a mild attention deficit, somatic complaints, and a feminized gender role. FISH with the 3p subtelomeric probe revealed that the deleted chromosome actually lacked the specific signal (n=10 cells). The patient's average intelligence confirms that euchromatic imbalances do not necessarily cause mental retardation and suggests that his deletion actually included the CALL gene, the Contactin 4 gene and other 3p26 genes related to intellectual capabilities; yet, the resulting hemizygosity either did not lead to haploinsufficiency or was minimally expressed. Moreover, the patient's peculiar cognitive and behavioral profile suggests that the 3p26 deletion is associated with a distinctive neuropsychological phenotype. Incidentally we comment on authorship and publication ethics in order to urge our institutional ethics committee to arbitrate authorship conflicts and thereby be consistent with its ethical commitment.
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PMID:Follow-up of an intelligent odd-mannered teenager with del(3)(p26). Remarks on authorship and ethical commitment. 1737 25