Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026827 (hypotonia)
 5,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Trisomy 16 (Ts16) mouse is considered an animal model of Down syndrome (human trisomy 21). Whole-cell patch-clamp was used to evaluate potassium and chloride currents of cultured tongue muscle cells from fetal Ts16 and diploid mice. No difference was found in membrane capacitance between the two groups. K(+) and Cl(-) currents were pharmacologically isolated. K(+) conductance was reduced by 31% in Ts16 cells (373 pS/pF) compared with diploid cells (539 pS/pF). Cl(-) conductance was 51% larger in Ts16 cells (103 pS/pF) compared with diploid cells (68 pS/pF). However kinetics for K(+) and Cl(-) currents did not differ between the cell types. An increase in Cl(-) conductance and a decrease in K(+) conductance in Ts16 muscle cells, if present in muscle of Down syndrome subjects, might account for the observed hypotonia in these subjects.
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PMID:Abnormal chloride and potassium conductances in cultured embryonic tongue muscle from trisomy 16 mouse. 1096 Jun 88

We present the case of a 7-month-old girl with the karyotype 46,XX, der(13) t(2;13)(p23;p11.2).ish der(13)(wcp2+) de novo. Painting confirmed that the additional segment on 13p was of chromosome 2 origin, resulting in trisomy 2p23 -->2pter. The child had a prominent forehead with a flat hemangioma, depressed nasal bridge, protruding tongue, posteriorly angulated ears, esotropia with poor abduction of the right eye, bilateral severe myopia (-5.5 D), retinal hypopigmentation, foveal hypoplasia, and striking left optic nerve hypoplasia. She also had pectus excavatum, a protruding abdomen with diastasis recti, generalized hypotonia, delayed fine and gross motor development, grade II reflux on the left side, and grade III-IV reflux on the right side. An EEG showed epileptiform discharges. Computed tomographic scan of the brain showed decreased white matter, but magnetic resonance imaging showed normal results.
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PMID:Phenotype of a patient with pure partial trisomy 2p(p23-->pter). 1148 12

A derivative chromosome 8 was observed in a newborn boy who presented with low birth weight, multiple congenital anomalies, and dysmorphic face. The der(8) was further characterized at age 18 months by a high resolution G-banding analysis, spectral karyotyping, and fluorescence in situ hybridization (FISH) with multiple DNA probes. The karyotype was described as 46,XY,der(8)(qter-->q24.13::p21.3-->p23.3::p23.3-->qter), representing an inverted duplication of region 8p21.3-->p23.3 and a duplication of region 8q24.13-->qter, which attaches to the duplicated short arm segment at 8p21.3. Different from previously reported patients with an inverted duplication (8p), no deletion was detected in the distal region of 8p in this case. This young child had manifested a broad nasal bridge, micrognathia, cleft lip, hydrocephalus, partial agenesis of the corpus callosum, Dandy-Walker malformation, congenital heart defects, dysplastic kidneys, hydronephrosis, marked hypotonia, and significant psychomotor retardation. These features are compared with those commonly seen in cases with an inverted duplication of 8p and cases with a partial trisomy of 8q.
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PMID:Molecular cytogenetic characterization of a derivative chromosome 8 with an inverted duplication of 8p21.3-->p23.3 and a rearranged duplication of 8q24.13-->qter. 1290 Sep 8

Down's syndrome (DS) is a major cause of mental retardation, hypotonia and delayed development. Murine models of DS carrying large murine or human genomic fragments show motor alterations and memory deficits. The specific genes responsible for these phenotypic alterations have not yet been defined. DYRK1A, the human homolog of the Drosophila minibrain gene, maps to the DS critical region of human chromosome 21 and is overexpressed in DS fetal brain. DYRK1A encodes a serine-threonine kinase, probably involved in neuroblast proliferation. Mutant Drosophila minibrain flies have a reduction in both optic lobes and central brain, showing learning deficits and hypoactivity. We have generated transgenic mice (TgDyrk1A) overexpressing the full-length cDNA of Dyrk1A. TgDyrk1A mice exhibit delayed cranio-caudal maturation with functional consequences in neuromotor development. TgDyrk1A mice also show altered motor skill acquisition and hyperactivity, which is maintained to adulthood. In the Morris water maze, TgDyrk1A mice show a significant impairment in spatial learning and cognitive flexibility, indicative of hippocampal and prefrontal cortex dysfunction. In the more complex repeated reversal learning paradigm, this defect turned out to be specifically related to reference memory, whereas working memory was almost unimpaired. These alterations are comparable with those found in the partial trisomy chromosome 16 murine models of DS and suggest a causative role of DYRK1A in mental retardation and in motor anomalies of DS.
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PMID:Neurodevelopmental delay, motor abnormalities and cognitive deficits in transgenic mice overexpressing Dyrk1A (minibrain), a murine model of Down's syndrome. 1155 28

We report on a familial t(4;7)(q28;p22) with 2:2 adjacent-1 unbalanced segregation producing duplication of 4q28-->qter in multiple offspring. Within the large four-generation pedigree, a carrier had a reproductive outcome that was approximately equal for 1) the balanced translocation, 2) normal chromosomes, and 3) viable 4q trisomy or pregnancy loss. The three individuals with chromosomal confirmation of trisomy 4q28-->qter (comprising approximately 1.8% of the haploid autosomal length) had similar mental and developmental retardation, hypotonia, restricted speech, seizures, and facial anomalies but no cardiac, renal, or skeletal anomalies. It is suggested that these latter severe malformations, associated with the classic 4q2 to 3 group of anomalies, were from an imbalance outside 4q28-->qter and were not necessarily related to the relatively large size of the trisomic segment. Multiple different chromosomes are reported to be rearranged with 4q in the production of distal 4q trisomy. The incidence of 4q rearrangement remains unexplained, but once it is present in a family, viability of a large trisomy in 4q seems to explain the number of affected individuals reported.
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PMID:High risk for unbalanced segregation of some reciprocal translocations: a large pedigree containing distal 4q trisomy from t(4;7)(q28;p22). 1174 10

Our objective was to examine ultrasound findings with outcomes in cases of rare chromosomal abnormalities diagnosed during pregnancy. Results of cytogenetic studies obtained from amniocenteses and chorionic villus samplings (CVS) from 1994-2000 were reviewed. Only those examples of rare chromosomal abnormalities with little information on the associated outcome were included. Cases of autosomal trisomy (13, 18, and 21), sex chromosome aneuploidy, and reciprocal or Robertsonian translocations were excluded. Ultrasound findings and outcomes were reviewed. In all, 8,642 procedures of amniocenteses and 557 of CVS were performed; 21 cases met the inclusion criteria. Parental karyotypes were obtained for 19 couples and the karyotypic abnormalities were de novo in 13. Abnormal ultrasound findings were present in 14 pregnancies, with the following outcomes: seven underwent dilatation and evacuation (D&E), with abnormal findings in two (although examination was limited by fragmentation); one medical termination with micrognathia and low-set ears; one fetal demise; one neonatal demise; three surviving neonates with abnormalities (one each with congenital kyphosis, hydronephrosis, and hypotonia), and one newborn was normal. There were seven patients without abnormal ultrasound findings with the following outcomes: three underwent D&E, with abnormal findings in two, one child with a colobomatous optic nerve, and two apparently normal infants. Follow-up was not available in one patient. We conclude that when rare karyotypes and ultrasound abnormalities are present, poor outcomes are likely. Even with normal ultrasound findings, abnormalities may be present. These data may assist in counseling patients when testing reveals such chromosomal abnormalities.
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PMID:Correlation between rare chromosomal abnormalities and prenatal ultrasound findings. 1180 99

We report a 5-year-old boy with a small de novo marker chromosome derived from the proximal short arm of chromosome 17. His clinical features include hypotonia, global developmental delay, oval face with large nose and prominent ears, and ligamentous laxity of the fingers. Magnetic resonance imaging of the brain demonstrated mildly delayed myelination. G-band chromosome analysis revealed mosaicism for a small marker chromosome in 85% of the peripheral blood cells analyzed. Fluorescence in situ hybridization and microsatellite polymorphism studies showed that the der(17) was of maternal origin and included genetic material from the 17p10-p12 region, but did not contain the PMP22 gene. One breakpoint mapped within the centromere and the second breakpoint mapped adjacent to the Charcot-Marie-Tooth disease type 1A proximal low-copy repeat (CMT1A-REP). We compare the clinical characteristics of our patient with those previously reported to have a duplication involving the proximal short arm region of chromosome 17 to further delineate the phenotype of trisomy 17pl0-p12.
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PMID:Trisomy 17p10-p12 resulting from a supernumerary marker chromosome derived from chromosome 17: molecular analysis and delineation of the phenotype. 1190 33

The clinical significance of trisomy 20 mosaicism detected prenatally remains uncertain due to the rarity of liveborn cases with inconsistent clinical findings, and lack of long-term follow-up and outcome. We describe a case of true trisomy 20 mosaicism in a liveborn girl with maternal uniparental isodisomy of chromosome 20 in the diploid blood cells. Trisomy 20 mosaicism was originally detected in amniotic fluid (98%) and was confirmed in the term placenta (100%), as well as in the blood (10%) and urine sediment (100%) of the neonate. There was intrauterine and postnatal growth retardation, but otherwise the newborn manifested no gross abnormalities. At 9 months of age moderate psychomotor retardation, central hypotonia with peripheral hypertonia, numerous minor morphogenetic variants, marked kyphosis, and extensive Mongolian spot were observed. To our knowledge this represents the first case of trisomy 20 mosaicism detected prenatally and confirmed in different tissues of the newborn, where uniparental disomy was demonstrated in the diploid cell line. The clinical and laboratory findings in our patient are compared with those of five previously reported cases of UPD20, suggesting that maternal UPD20 might be associated with a characteristic phenotype.
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PMID:Maternal uniparental isodisomy 20 in a foetus with trisomy 20 mosaicism: clinical, cytogenetic and molecular analysis. 1240

11q trisomy is associated with a recognizable pattern of multiple malformations. Review of the literature reveals the following recurrent themes common to complex and isolated 11q trisomy: mental retardation, pre- and postnatal growth retardation, hypotonia, a distinct pattern of facial features, congenital heart defects, and limb malformations. We report four patients with partial trisomy 11q, none of which arose from the common 11/22 translocation. Three of the four patients had the previously unreported finding of upper airway obstruction secondary to a malformed epiglottis. The critical region for this malformation appears to be 11q21-23.2.
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PMID:Upper airway malformation associated with partial trisomy 11q. 1283 51

We report a 14-month-old girl with submucous cleft palate, resolving mild hydrocephalus, severe hypotonia and joint contractures. The finding of extreme hydrocephalus, cleft palate and club feet in a fetus of the mother's previous pregnancy suggested an inherited defect. Chromosome analysis and FISH studies in the proband revealed an abnormal homolog 13 resulting in a duplication of distal chromosome 7q, 7q35-qter, and a very small associated deletion of distal chromosome 13q, 13q34-qter. The mother showed the balanced translocation. Similar clinical signs have been described with larger distal 7q duplications. Our findings suggest that 7q35-qter, and possibly the gene for sonic hedgehog (SHH) on 7q36, is the critical region for the typical facial features and the profound hypotonia observed in the 'trisomy of distal 7q' syndrome.
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PMID:Small inherited terminal duplication of 7q with hydrocephalus, cleft palate, joint contractures, and severe hypotonia. 1286 76


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