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Query: UMLS:C0026827 (hypotonia)
 5,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Down syndrome (DS) is a major cause of mental retardation and congenital heart disease. Besides a characteristic set of facial and physical features, DS is associated with congenital anomalies of the gastrointestinal tract, an increased risk of leukemia, immune system defects, and an Alzheimer-like dementia. Moreover, DS is a model for the study of human aneuploidy. Although usually caused by the presence of an extra chromosome 21, subsets of the phenotypic features of DS may be caused by the duplication of small regions of the chromosome. The physical map of chromosome 21 allows the molecular definition of the regions duplicated in these rare cases of partial trisomy. As a first step in identifying the genes responsible for individual DS features and their pathophysiology, a panel of cell lines derived from 16 such individuals has been established and the molecular break points have been determined using fluorescence in situ hybridization and Southern blot dosage analysis of 32 markers unique to human chromosome 21. Combining this information with detailed clinical evaluations of these patients, we have now constructed a "phenotypic map" that includes 25 features and assigns regions of 2-20 megabases as likely to contain the genes responsible. This study provides evidence for a significant contribution of genes outside the D21S55 region to the DS phenotypes, including the facies, microcephaly, short stature, hypotonia, abnormal dermatoglyphics, and mental retardation. This strongly suggests DS is a contiguous gene syndrome and augurs against a single DS chromosomal region responsible for most of the DS phenotypic features.
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PMID:Down syndrome phenotypes: the consequences of chromosomal imbalance. 819 71

We present two unrelated cases of partial trisomy for the short arm of chromosome 5, the first such cases reported in Japan. The features are characterized by hypertelorism, low set ears, arachnodactyly, laryngostenosis, hypotonia and some cerebral malformation. The characteristic facial expression and arachnodactyly are the key features used to diagnose this disorder. A high-resolution chromosome banding technique showed that the karyotype of the first patient was 46,XX,inv dup(5) (p13.1-->p15.3) de novo and that of the second patient was 46,XX,dir dup(5) (p13.3-->p15.2) de novo. The similar symptoms in the two cases, despite the difference in karyotypes, were caused by duplication of 5p including segment 5p13. This would be a key site for this disorder.
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PMID:Partial trisomy for short arm of chromosome 5. 837 27

We report on an aneuploidy syndrome due to the unbalanced segregation of a familial translocation (4;21)(p16.3;q22.1) causing a partial 4p monosomy and a partial 21q trisomy. The three affected children presented with severe failure to thrive, short stature, microcephaly, profound hypotonia, and mental retardation. The face, very similar in the three children, is characterized by frontal bossing, upslanting of the palpebral fissures, short nose, and deep set ears, giving the overall appearance of the Down syndrome. The molecular study has defined the aneuploid segment on both 4p and 21q. Most of the Down syndrome critical region was found to the trisomic, while only part of the candidate Wolf-Hirschhorn syndrome critical region was deleted, suggesting that this region is not critical for the major malformations characteristic for WHS.
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PMID:Molecular and cytogenetic characterization of a recurrent unbalanced translocation (4;21)(p16.3;q22.1): relevance to the Wolf-Hirschhorn and Down syndrome critical regions. 872 87

A genetics evaluation was requested for a 6-week-old infant with multiple congenital malformations including mild craniofacial anomalies, truncal hypotonia, hypospadias, and a ventriculoseptal defect. Blood obtained for chromosome analysis revealed an abnormal chromosome 4. Paternal chromosome analysis showed a 46,XY, inv ins (3;4)(p21.32;q25q21.2), inv(4)(p15.3q21.2) karyotype. Therefore, the proband's chromosome 4 was the unbalanced product of this insertional translocation from the father resulting in partial monosomy 4q. Additionally, the derivative 4 had a pericentric inversion which was also seen in the father's chromosome 4. During genetic counseling, the proband's 2-year-old brother was evaluated. He was not felt to be abnormal in appearance, but was described as having impulsive behavior. Chromosome analysis on this child revealed 46,XY,der(3)inv ins(3;4)(p21.32;q25q21.2)pat. This karyotype results in partial trisomy 4q. FISH using two-color "painting" probes for chromosomes 3 and 4 confirmed the G-banded interpretation in this family. The segregation seen in this family resulted in both reciprocal products being observed in the two children, with partial 4q monosomy showing multiple congenital anomalies, and partial 4q trisomy showing very few phenotypic abnormalities.
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PMID:Segregation of a paternal insertional translocation results in partial 4q monosomy or 4q trisomy in two siblings. 874 10

Most cases of Down syndrome (DS) result from a supernumerary chromosome 21; however, there are rare cases in which DS is due to partial trisomy of chromosome 21, involving various segments of the chromosome. The characterization of cases of DS that are due to partial trisomy 21 allows the phenotype to be correlated with the genotype. We present a case with features of DS and a partial trisomy of chromosome 21 inherited from a paternal balanced translocation involving chromosomes 13 and 21. Fluorescence in situ hybridization analysis using yeast artificial chromosome (YAC) probes mapped the breakpoint to 21q22.1, within YAC 230E8, which contains markers CBR, D21S333 and D21S334. Further mapping using cosmids positioned the breakpoint proximal to CBR. The patient was also monosomic for the distal portion of chromosome 13 (q33-qter). Many phenotypic features of DS were present including hypotonia, flat occiput, flat facies, up-slanted palpebral fissures, epicanthic folds, flat nasal bridge, macroglossia, open mouth, small ears and a heart murmur. This case further supports the contention that the majority of the phenotypic features of DS map to 21q22-qter and further refines the location of some of them. In addition to the DS phenotype, the patient had a prominent upper maxilla with protruding upper incisors, and low levels of the coagulation factors VII and X, consistent with a syndrome resulting from monosomy 13q33-qter. Since some features overlap between the two syndromes, including severe mental retardation, it is unclear to what extent monosmy for 13q33-qter, trisomy for 21q22.1-qter, or a combination of both, contributed to the common features of the phenotype.
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PMID:YAC and cosmid FISH mapping of an unbalanced chromosomal translocation causing partial trisomy 21 and Down syndrome. 879 23

We report a case of mosaicism for three cell lines: 45,X, 46,XX, and 47,XX, + 12, diagnosed prenatally by amniocentesis done for advanced maternal age. Cord blood from the baby showed mosaicism for 45,X and 46,XX; cultures derived from multiple placental sites, villi, cord, membrane, and skin had varying proportions of all three cell lines. The patient at 18 months of age has mild physical dysmorphisms, hypotonia, delay in gross motor development, and age-appropriate cognitive development. The literature reveals variable outcomes for individuals with either mosaic trisomy 12 or mosaic Turner syndrome. Parental origin of the chromosome involved in a proposed corrected trisomy and/or the percentage of cell types in affected organs might account for the variability in outcomes seen.
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PMID:Trisomy 12/monosomy X/normal female mosaicism: prenatal detection and confirmation in a liveborn. 887 84

The case of a 1.5 year old girl with clinical traits of craniofacial dysmorphy, hypotonia, polydactyly and moderate mental retardation is presented. Routine cytogenetic study revealed the presence of a large additional chromosomal fragment associated with the nucleolus organizing region on one of chromosomes 13. The banding pattern suggested the additional fragment was a part of the long arm of this chromosome. The set of clinical symptoms was only partly consistent with those characteristic for trisomy 13q2 and 3. Application of the FISH technique with a chromosome 13 specific library enabled final confirmation of the origin of the extra chromosome fragment from the long arm of chromosome 13. The presented case proves the usefulness of the FISH technique for the diagnosis of chromosomal aberrations and for adequate clinical interpretation of cytogenetic results.
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PMID:[Partial trisomy of chromosome 13--diagnosis confirmed with the FISH in situ hybridization technique]. 896 97

We describe a de novo trisomy 5p in a 1-year-old severely retarded boy. The complete short arm of chromosome 5 segregated as an additional marker chromosome in all metaphases. The marker was identified as 5p by conventional cytogenetic techniques (GTG, GBG, CBG) and molecular cytogenetic techniques (whole chromosome-painting probe, probes for the cri-du-chat region and the centromere, and additionally high-resolution multicolor banding using a chromosome 5-specific DNA probe cocktail). The clinical findings were similar to the established trisomy 5p phenotype including macrocephaly, facial abnormalities, tracheobronchial defects with subsequent respiratory infections, hypotonia, and psychomotor retardation. To the best of our knowledge this is the first description of an isolated complete 5p trisomy without involvement of the aberrant chromosome in any structural chromosomal rearrangements.
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PMID:De novo complete trisomy 5p: clinical report and FISH studies. 1086 86

Trisomy 5p and Miller-Dieker syndromes frequently are the result of unbalanced segregations of reciprocal translocations of chromosomes 5 and 17 with other autosomes. The critical regions for the expression of the mentioned syndromes have been mapped to 5p13-->pter, and 17p13.3-->pter. In this report, we describe an 8-year-old girl with mental retardation, postnatal growth deficiency, generalized muscular hypotonia, seizures, microcephaly, cortical atrophy, partial agenesis of corpus callosum, cerebral ventriculomegaly, facial anomalies, patent ductus arteriosus, pectus excavatum, long fingers, and bilateral talipes equinovarus caused by the presence of a 46,XX,der(17)t(5;17)(p13.1;p13.3)mat chromosome complement. Cytogenetic studies of the family confirmed a balanced reciprocal translocation (5;17)(p13.1;p13.3) in her mother, maternal grandfather, maternal aunt, and a female first cousin. Fluorescence in situ hybridization studies on the mother and the proposita using three probes, which map to distal 17p, confirmed the reciprocal translocation in the mother and a terminal deletion in the patient, which resulted in the retention of LIS1 and D17S379 loci and deletion of the 17p telomere. These findings and the phenotype of the proposita, strongly suggest that genes telomeric to LIS1 and locus D17S379 are involved in many clinical findings, including the minor facial anomalies of the Miller-Dieker syndrome.
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PMID:Miller-Dieker syndrome and trisomy 5p in a child carrying a derivative chromosome with a microdeletion in 17p13.3 telomeric to the LIS1 and the D17S379 loci. 1040 60

A child with monosomy for the distal part of the short arm of chromosome 3 (3p25-->pter) and trisomy for the terminal portion of the long arm of chromosome 17 (17q23-->qter) is presented. This unbalanced karyotype was derived from a balanced reciprocal 3p/17q translocation in the phenotypically normal mother. Main clinical features in the proband included growth and mental retardation, hypotonia, hirsutism, micro/brachycephaly, triangular face, synophris, broad and full nose, long philtrum, narrow upper lip, low set, posteriorly turned ears, anteriorly placed anus and congenital heart defect (Tetralogy of Fallot). Most of these clinical manifestations have been constantly reported in previous cases with terminal 3p deletion.
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PMID:A 3p deletion syndrome in a child with both del(3)(p25-->pter) and dup(17)(q23-->qter). 1043 22


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