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)

Paracentric inversions are one of the common chromosomal rearrangements typically associated with a normal phenotype. However, if dosage-sensitive genes are disrupted by the breakpoints, an abnormal phenotype could result. Detection of paracentric inversions often relies on careful high resolution banding, which has limited sensitivity. We report here cytogenetic studies performed on a 4-year-old female patient with global developmental delay, hypotonia, and dysmorphic features. The initial cytogenetic evaluation by G-banding revealed a de novo inversion of chromosome 14. Subsequent array CGH analysis using both a targeted BAC array and a high-resolution oligonucleotide array revealed microdeletions at the breakpoints of 14q21.1 (0.8 Mb) and 14q23.1 (0.9 Mb). Unexpectedly, a microdeletion in the region of 16q23.1 (1.3 Mb) was also identified, which overlaps with the common fragile site FRA16D. Parental chromosome and FISH analyses were normal, supporting the conclusion that these microdeletions were de novo in the patient and likely contributed to her abnormal phenotype. The case report presented illustrates the value of using high-resolution microarray analysis for phenotypically abnormal individuals with apparently balanced chromosomal rearrangements, including inversions.
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PMID:De novo and complex imbalanced chromosomal rearrangements revealed by array CGH in a patient with an abnormal phenotype and apparently "balanced" paracentric inversion of 14(q21q23). 1862 51

We report a patient with a unique and complex cytogenetic abnormality involving mosaicism for a small ring X and deleted Xp derivative chromosome with tandem duplication at the break point. The patient presented with failure to thrive, muscular hypotonia, and minor facial anatomic anomalies, all concerning for Turner syndrome. Brain MRI revealed mild thinning of the corpus callosum, an apparent decrease in ventricular white matter volume, and an asymmetric myelination pattern. Array comparative genome hybridization analysis revealed mosaicism for the X chromosome, deletion of the short arm of an X chromosome, and a duplication of chromosome region Xp11.21-p11.22. G-banded chromosome and FISH analyses revealed three abnormal cell lines: 46,X,der(X)del(X)(p11.23)dup(X)(p11.21p11.22)/46,X,r(X)(q11.1q13.1)/45,X. The small ring X chromosome was estimated to be 5.2 Mb in size and encompassed the centromere and Xq pericentromeric region. X chromosome inactivation (XCI) studies demonstrated a skewed pattern suggesting that the ring X remained active, likely contributing to the observed clinical features of brain dysmyelination. We hypothesize that a prezygotic asymmetric crossing over within a loop formed during meiosis in an X chromosome with a paracentric inversion resulted in an intermediate dicentric chromosome. An uneven breakage of the dicentric chromosome in the early postzygotic period might have resulted in the formation of one cell line with the X chromosome carrying a terminal deletion and pericentromeric duplication of the short arm and the second cell line with the X chromosome carrying a complete deletion of Xp. The cell line carrying the deletion of Xp could have then stabilized through self-circularization and formation of the ring X chromosome.
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PMID:Mosaicism for r(X) and der(X)del(X)(p11.23)dup(X)(p11.21p11.22) provides insight into the possible mechanism of rearrangement. 1865 7

Wolf-Hirschhorn syndrome (WHS) is a well-known multiple congenital anomalies/mental retardation syndrome, firstly described in 1961 by Cooper and Hirschhorn. Its frequency is estimated as 1/50,000-1/20,000 births, with a female predilection of 2:1. The disorder is caused by partial loss of material from the distal portion of the short arm of chromosome 4 (4p16.3), and is considered a contiguous gene syndrome. No single gene deletions or intragenic mutations have been shown to confer the full WHS phenotype. Since the disorder was brought to the attention of geneticists, many additional cases have been published. Only in 1999, however, were the first data on the natural history brought to the attention of the medical community. The purpose of the present study is to help delineate in more detail and over a longer period of time, the natural history of WHS, in order to establish appropriate health supervision and anticipatory guidance for individuals with this disorder. We have collected information on 87 patients diagnosed with WHS (54 females and 33 males) both in USA and Italy. Age at first observation ranged between newborn and 17 years. Twenty patients have been followed from 4 months to 23 years. The deletion proximal breakpoint varied from 4p15.32 to 4p16.3, and, by FISH, was terminal and included both WHSCR. Deletion was detected by standard cytogenetics in 44/87 (50.5%) patients, whereas FISH was necessary in the other 43 (49.5%). Array-CGH analysis at 1 Mb resolution was performed in 34/87 patients, and, in 15/34 (44%), showed an unbalanced translocation leading to both a 4p monosomy and a partial trisomy for another chromosome arm. Six more patients had been previously shown to have an unbalanced translocation by karyotype analysis or FISH with a WHS-specific probe. Sixty-five of 87 patients had an apparent pure, de novo, terminal deletion; and 1/87 a tandem duplication of 4p16.1p16.3 associated with 4p16.3pter deletion. Age at diagnosis varied between 7 months gestation and 16 years. Ninety-three percent had a seizure disorder with a good outcome; 80% had prenatal onset growth deficiency followed by short stature and slow weight gain; 60% had skeletal anomalies; 50% had heart lesions; 50% had abnormal tooth development; and 40% had hearing loss. Distinctive EEG findings were seen in 90%. Structural CNS anomalies were detected in 80%. Global developmental delay of varying degrees was present in all patients. Almost 50% was able to walk either alone or with support. Hypotonia was present in virtually all patients. A global improvement was observed in all individuals, over time. Our survey has also shown how the characteristic facial phenotype tends to be less pronounced in those patients with a smaller deletion, and microcephaly is not observed in the patients with certain cryptic unbalanced translocations.
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PMID:Update on the clinical features and natural history of Wolf-Hirschhorn (4p-) syndrome: experience with 87 patients and recommendations for routine health supervision. 1893 24

The inv dup(15) or idic(15) syndrome displays distinctive clinical findings represented by early central hypotonia, developmental delay and intellectual disability, epilepsy, and autistic behaviour. Incidence at birth is estimated at 1 in 30,000 with a sex ratio of almost 1:1. Developmental delay and intellectual disability affect all individuals with inv dup(15) and are usually moderate to profound. Expressive language is absent or very poor and often echolalic. Comprehension is very limited and contextual. Intention to communicate is absent or very limited. The distinct behavioral disorder shown by children and adolescents has been widely described as autistic or autistic-like. Epilepsy with a wide variety of seizure types can occur in these individuals, with onset between 6 months and 9 years. Various EEG abnormalities have been described. Muscle hypotonia is observed in almost all individuals, associated, in most of them, with joint hyperextensibility and drooling. Facial dysmorphic features are absent or subtle, and major malformations are rare. Feeding difficulties are reported in the newborn period.Chromosome region 15q11q13, known for its instability, is highly susceptible to clinically relevant genomic rearrangements, such as supernumerary marker chromosomes formed by the inverted duplication of proximal chromosome 15. Inv dup(15) results in tetrasomy 15p and partial tetrasomy 15q. The large rearrangements, containing the Prader-Willi/Angelman syndrome critical region (PWS/ASCR), are responsible for the inv dup(15) or idic(15) syndrome. Diagnosis is achieved by standard cytogenetics and FISH analysis, using probes both from proximal chromosome 15 and from the PWS/ASCR. Microsatellite analysis on parental DNA or methylation analysis on the proband DNA, are also needed to detect the parent-of-origin of the inv dup(15) chromosome. Array CGH has been shown to provide a powerful approach for identifying and detecting the extent of the duplication. The possible occurrence of double supernumerary isodicentric chromosomes derived from chromosome 15, resulting in partial hexasomy of the maternally inherited PWS/ASCR, should be considered in the differential diagnosis. Large idic(15) are nearly always sporadic. Antenatal diagnosis is possible. Management of inv dup(15) includes a comprehensive neurophysiologic and developmental evaluation. Survival is not significantly reduced.
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PMID:The inv dup (15) or idic (15) syndrome (Tetrasomy 15q). 1901 26

We report on 3 kindred patients with terminal 11q monosomy and distal 22q trisomy involving the SHANK3 gene, resulting from a subtle familial translocation t(11;22)(q24.2;q13.33). The patients presented with the characteristic symptoms of Jacobsen syndrome (JBS), including: mental retardation, short stature, and craniofacial dysmorphism in all 3 cases; cardiac defects in 2 cases; and thrombocytopenia, brain abnormality, eye coloboma, recurrent infections, cryptorchidism and toe anomalies in single cases. The oldest patient also had Hashimoto disease and diabetes mellitus type 2. So far, these 2 conditions have not been reported in adult patients with JBS. Features typical for distal 22q trisomy in our patients include muscular hypotonia and prenatal failure to thrive, seen in 2 and 1 cases, respectively. We also present a family member with 11q24.2-qter trisomy and 22q13.33-qter monosomy, whose clinical phenotype is partially overlapping with several dysmorphic features of JBS. In addition, multiple pregnancy losses and infantile deaths occurred in this family, suggesting that these chromosomal imbalances may produce a lethal phenotype. FISH with a panel of BAC probes determined the accurate sizes of the deletion 11q (9.9 Mb) and trisomy 22q (0.8 Mb). To date, only 5 cases of submicroscopic 22q13.3-qter trisomy have been reported. A detailed clinical description of our patients, along with a precise cytogenetic designation of chromosomal breakpoints, allow further refinement of genotype-phenotype correlation for distal imbalances in 11q and 22q.
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PMID:Subtle familial translocation t(11;22)(q24.2;q13.33) resulting in Jacobsen syndrome and distal trisomy 22q13.3: further details of genotype-phenotype maps. 1902 87

Distal Xq disomy in males results in characteristic phenotypes that typically include mental retardation, microcephaly, prominent hypotonia and hypogonadism. The 8-year-old male patient reported here presented with mental retardation, prominent ears, abnormally wide and unstable gait and flat occiput. He did not have microcephaly or hypogonadism. Subtelomeric multi-fluorescence in-situ hybridization analysis identified a duplicated terminal portion of chromosome Xq/Yq located distally on Yp. Further analysis of the duplicated region using additional FISH probes, specific for the distal Xq and Yp chromosomal regions, and array comparative genomic hybridization analysis using the 244 K oligo-array of Agilent, showed that it spans approximately 2.15 Mb of the terminal Xq region and includes MECP2 but not L1CAM gene. This is the smallest well-characterized terminal Xq duplication reported to date. Genes proximal to MECP2 that are not duplicated in our patient are likely responsible for additional clinical manifestations including characteristic facial dysmorphic features, microcephaly, hypogonadism and more severe hypotonia, as noted in patients with larger distal Xq duplications. Our patient's features are similar to previously reported MECP2 gene duplication cases, thus suggesting minor or no contribution of duplicated genes distal of MECP2 to the reported phenotype.
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PMID:De-novo 2.15 Mb terminal Xq duplication involving MECP2 but not L1CAM gene in a male patient with mental retardation. 1909 26

To date, 10 cases of recombinant of chromosome 4 pericentric inversion involving sub-bands p14p15 and q35 have been described. We report on the first case analyzed using array-CGH in a female infant presenting psychomotor and growth retardation, facial anomalies, axial hypotonia, short neck, wide spaced nipples and cardiac defects. Conventional karyotype associated to FISH revealed a recombinant chromosome 4 with partial 4p duplication and 4q deletion derived from a paternal pericentric inversion. Array-CGH allowed us to precise rec4 breakpoints: the proposita carried a small 4.82-4.97 Mb 4q35.1 terminal deletion and a large 35.3-36.7 Mb 4p15.1 terminal duplication. Duplications of the distal 2/3 of short arm of chromosome 4 give rise to recognizable craniofacial features but no specific visceral malformation. A contrario small terminal 4q deletions are associated with cardiac defects. This case and review of literature suggest that two genes ArgBP2 and PDLIM3, located at 4q35.1 and both involved in cardiac and muscle development, could be responsible for cardiac defects observed in terminal 4q35.1 deletions.
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PMID:Molecular cytogenetic characterization of a 4p15.1-pter duplication and a 4q35.1-qter deletion in a recombinant of chromosome 4 pericentric inversion. 1916 Nov 54

Interstitial deletions involving 6q11-q14 have been reported in less than 20 patients, with the breakpoints studied by G-banding alone. We report on seven patients with 6q11-q14 interstitial deletions of variable size. The breakpoints were studied by G-banding, dual-color BAC-FISH and SNP array. The results showed the molecular breakpoints differed significantly from the ones obtained from G-banding. The breakpoints studied by BAC-FISH were consistent with the ones from SNP array. Some characteristics from this cohort are consistent with previous reports, but many typical features are lacking in our patients. The cardinal features of 6q11-q14 interstitial deletions in this cohort include: umbilical hernia, hypotonia, short stature, characteristic facial features of upslanting palpebral fissures, low set and/or dysplastic ears, high arched palate, urinary tract anomalies, and skeletal/limb anomalies.
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PMID:Molecular breakpoint mapping of 6q11-q14 interstitial deletions in seven patients. 1921 33

Distal Xq duplications refer to chromosomal disorders resulting from involvement of the long arm of the X chromosome (Xq). Clinical manifestations widely vary depending on the gender of the patient and on the gene content of the duplicated segment. Prevalence of Xq duplications remains unknown. About 40 cases of Xq28 functional disomy due to cytogenetically visible rearrangements, and about 50 cases of cryptic duplications encompassing the MECP2 gene have been reported. The most frequently reported distal duplications involve the Xq28 segment and yield a recognisable phenotype including distinctive facial features (premature closure of the fontanels or ridged metopic suture, broad face with full cheeks, epicanthal folds, large ears, small and open mouth, ear anomalies, pointed nose, abnormal palate and facial hypotonia), major axial hypotonia, severe developmental delay, severe feeding difficulties, abnormal genitalia and proneness to infections. Xq duplications may be caused either by an intrachromosomal duplication or an unbalanced X/Y or X/autosome translocation. In XY males, structural X disomy always results in functional disomy. In females, failure of X chromosome dosage compensation could result from a variety of mechanisms, including an unfavourable pattern of inactivation, a breakpoint separating an X segment from the X-inactivation centre in cis, or a small ring chromosome. The MECP2 gene in Xq28 is the most important dosage-sensitive gene responsible for the abnormal phenotype in duplications of distal Xq. Diagnosis is based on clinical features and is confirmed by CGH array techniques. Differential diagnoses include Prader-Willi syndrome and Alpha thalassaemia-mental retardation, X linked (ATR-X). The recurrence risk is significant if a structural rearrangement is present in one of the parent, the most frequent situation being that of an intrachromosomal duplication inherited from the mother. Prenatal diagnosis is performed by cytogenetic testing including FISH and/or DNA quantification methods. Management is multi-specialist and only symptomatic, with special attention to prevention of malnutrition and recurrent infections. Educational and rehabilitation support should be offered to all patients.
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PMID:Distal Xq duplication and functional Xq disomy. 1923 94

We report on a 4-year-old girl who presented with microcephaly, multiple minor anomalies of face and limbs, congenital heart defect, hypotonia, neuropsychomotor delay, deafness and seizures. A GTG-banded karyotype identified an additional fragment of unknown origin on the terminal region of 4p. Parental karyotypes were normal. FISH analysis using a whole chromosome paint probe for chromosome 4 and subtelomere probes showed a signal on the entire add (4) chromosome and loss of the 4p subtelomere region, respectively. Additional analysis using microsatellite markers for chromosome 4 and whole-genome array comparative genomic hybridization (array-CGH) identified a duplication of the region 4p13 --> 4p16.3. Her karyotype was thus interpreted as an inverted duplication with terminal deletion of 4p: 46,XX,der(4)(:p13 --> p16.3::p16.3 --> qter). The clinical features of our patient differed from those typically observed in Wolf-Hirschhorn syndrome and were more compatible with duplication 4(p14 --> p16.3), with preservation of the WHS critical region.
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PMID:Inv dup del(4)(:p13-->p16.3::p16.3-->qter) in a girl without typical manifestations of Wolf-Hirschhorn syndrome. 1944 29


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