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Results for “Microdeletion”

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PubMed1992

A microdeletion of less than 250 kb, including the proximal part of the FMR-I gene and the fragile-X site, in a male with the clinical phenotype of fragile-X syndrome.

A gene designated "FMR-1" has been isolated at the fragile-X locus. One exon of this gene is carried on a 5.1-kb EcoRI fragment that exhibits length variation in fragile-X patients because of amplification of or insertion into a CGG-repeat sequence. This repeat probably represents the fragile site. The EcoRI fragment also includes an HTF island that is hypermethylated in fragile-X patients showing absence of FMR-1 mRNA. In this paper, we present further evidence that the FMR-1 gene is involved in the clinical manifestation of the fragile-X syndrome and also in the expression of the cellular phenotype. A deletion including the HTF island and exons of the FMR-1 gene was detected in a fragile X-negative mentally retarded male who presented the clinical phenotype of the fragile-X syndrome. The deletion involves less than 250 kb of genomic DNA, including DXS548 and at least five exons of the FMR-1 gene. These data support the hypothesis that loss of function of the FMR-1 gene leads to the clinical phenotype of the fragile-X syndrome. In the fragile-X syndrome, there are pathogenetic mechanisms other than amplification of the CGG repeat that do have the same phenotypic consequences.

Base Sequence↗
PubMed1989

An Xp22 microdeletion associated with ocular albinism and ichthyosis: approximation of breakpoints and estimation of deletion size by using cloned DNA probes and flow cytometry.

Ocular albinism of the Nettleship-Falls type (OA1) and X-linked ichthyosis (XI) due to steroid sulfatase (STS) deficiency are cosegregating in three cytogenetically normal half-brothers. The mother has patchy fundal hypopigmentation consistent with random X inactivation in an OA1 carrier. Additional phenotypic abnormalities that have been observed in other STS "deletion syndromes" are not present in this family. STS is entirely deleted on Southern blot in the affected males, but the loci MIC2X, DXS31, DXS143, DXS85, DXS43, DXS9, and DXS41 are not deleted. At least part of DXS278 is retained. Flow cytometric analysis of cultured lymphoblasts from one of the XI/OA1 males and his mother detected a deletion of about 3.5 million bp or about 2% of the X chromosome. Southern blot and RFLP analysis in the XI/OA1 family support the order tel-[STS-OA1-DXS278]-DXS9-DXS41-cen. An unrelated patient with the karyotype 46,X,t(X;Y) (p22;q11) retains the DXS143 locus on the derivative X chromosome but loses DXS278, suggesting that DXS278 is the more distal locus and is close to an XI/OA1 deletion boundary. If a contiguous gene deletion is responsible for the observed XI/OA1 phenotype, it localizes OA1 to the Xp22.3 region.

Arylsulfatases↗
PubMed1995

Microdeletion of chromosomal region 22q11 in DiGeorge syndrome: report of a case.

This is a case of chromosome 22q11 deletion in a female Chinese infant with DiGeorge syndrome. Cardiac anomalies included a type B interrupted aortic arch from the descending aorta with an aberrant right subclavian artery, a large ventricular septal defect, a small atrial septal defect and a large patent ductus arteriosus. This patient was small for her age and showed symptoms of feeding difficulties, chronic diarrhea and facial dysmorphisms (frontal bossing, hypertelorism, posteriorly rotated ears, fish-like mouth and micrognathia). Chest film did not reveal a thymic shadow. Immunological studies showed a low T-cell ratio (20%). Laboratory tests revealed a borderline low serum calcium level. The karyotype, 46, XX, del(22) (q11.21-->q11.23), was observed by high-resolution banding techniques. Cardiac surgery was successfully performed at 1 month of age. Operative findings confirmed aplasia of the thymus and the above complex cardiac anomalies. To our knowledge, this is the first Taiwanese case of DiGeorge syndrome proven immunologically and cytogenetically.

Chromosome Deletion↗
PubMed1995

The human homologue of the Drosophila melanogaster flightless-I gene (flil) maps within the Smith-Magenis microdeletion critical region in 17p11.2.

The Smith-Magenis syndrome (SMS) appears to be a contiguous-gene-deletion syndrome associated with a proximal deletion of the short arm of chromosome 17 in band p11.2. The spectrum of clinical findings includes short stature, brachydactyly, developmental delay, dysmorphic features, sleep disturbances, and behavioral problems. The complex phenotypic features suggest deletion of several contiguous genes. However, to date, no protein-encoding gene has been mapped to the SMS critical region. Recently, the Drosophila melanogaster flightless-I gene, fliI, and the homologous human cDNA have been isolated. Mutations in fliI result in loss of flight ability and, when severe, cause lethality due to incomplete cellularization with subsequent abnormal gastrulation. Here, we demonstrate that the human homologue (FLI) maps within the SMS critical region. Genomic cosmids were used as probes for FISH, which localized this gene to the 17p11.2 region. Somatic-cell hybrid-panel mapping further localized this gene to the SMS critical region. Southern blot analysis of somatic-cell hybrids and/or FISH analysis of lymphoblastoid cell lines from 12 SMS patients demonstrates the deletion of one copy of FLI in all SMS patients analyzed.

Animals↗
PubMed1995

X-linked progressive mixed deafness: a new microdeletion that involves a more proximal region in Xq21.

We report a large two-generation pedigree with seven affected males segregating for an X-linked mixed conductive sensorineural deafness. The patients present with atypical Mondini-like dysplasia, dilated petrous facial canal, dilatation of the internal auditory meatus fully connected with enlarged cochlear canals, and, in one patient, a wide bulbous posterior labyrinth. Obligatory carrier females are mildly affected. Molecular characterization of this family revealed a deletion of locus DXS169, in Xq21.1. Loci DXS72 and DXS26, which, respectively, flank DXS169 proximally and distally, were intact. Since a gene responsible for X-linked progressive mixed deafness with perilymphatic gusher (DFN3) has previously been assigned by deletion mapping to a slightly more distal interval between DXS26 and DXS121, this study indicates either two different deafness genes or the involvement of a very large region in Xq21.

Ear, Inner↗
PubMed1994

Evidence that the Saethre-Chotzen syndrome locus lies between D7S664 and D7S507, by genetic analysis and detection of a microdeletion in a patient.

The locus for Saethre-Chotzen syndrome, a common autosomal dominant disorder of craniosynostosis and digital anomalies, was previously mapped to chromosome 7p between D7S513 and D7S516. We used linkage and haplotype analyses to narrow the disease locus to an 8-cM region between D7S664 and D7S507. The tightest linkage was to locus D7S664 (Z = 7.16, theta = .00). Chromosomes from a Saethre-Chotzen syndrome patient with t(2;7) (p23;p22) were used for in situ hybridization with YAC clones containing D7S664 and D7S507. The D7S664 locus was found to lie distal to the 7p22 breakpoint, and the D7S507 locus was deleted from the translocation chromosomes. These genetic and physical mapping data independently show that the disease locus resides in this interval.

Acrocephalosyndactylia↗
PubMedDate not supplied

Constitutional interstitial deletion of 17(p11.2) (Smith-Magenis syndrome): a clinically recognizable microdeletion syndrome. Report of two cases and review of the literature.

We present two patients, a 12 year old Turkish and a 7 year old Italian girl, with severe mental retardation, multiple congenital malformations and a constitutional interstitial deletion of the short arm of chromosome 17, del(17) (11.2). The main clinical features of this syndrome which is also referred to as the Smith-Magenis syndrome consist of a broad flat midface with brachycephaly, broad nasal bridge, brachydactyly, speech delay, hoarse deep voice and peripheral neuropathy. Behavioural abnormalities include hypermotility, self mutilation and sleep disturbances. The remarkable consistency of the main clinical features of the 59 patients documented so far permits the clinical diagnosis of this syndrome; a fact which is of importance, since many of the reported patients--including ours--were considered normal on earlier cytogenetic studies.

Abnormalities, Multiple↗
PubMed1997

Microdeletion oe chromosomal region 7Q11.23 in Williams syndrome.

We report two children with typical Williams syndrome facial appearance, growth deficiency and developmental delay. Both had supravalvular aortic stenosis (SVAS) and peripheral pulmonary stenosis (PPS), but no hypercalcemia. Chromosomal study in the first case, a 40-day-old girl, revealed a cytogenetically visible proximal interstitial deletion of the 7q11.22-11.23 segment. Another patient, a 3-year-old boy, with a normal karyotype, had milder phenotype with spontaneous remission of SVAS and PPS. Both patients showed allelic loss of the elastin (ELN) gene, exhibiting a submicroscopic deletion at 7q11.23, which was detected by fluorescence in situ hybridization (FISH). The results support the usefulness of FISH for detection of ELN gene deletion as an initial diagnostic assay for patients with SVAS or Williams syndrome. To our knowledge, these are the first cases of Williams syndrome in Taiwanese patients to be proven clinically, cytogenetically and by molecular analysis.

Chromosome Deletion↗
PubMed1997

Velocardiofacial manifestations and microdeletions in schizophrenic inpatients.

Velocardiofacial syndrome (VCFS) is associated with an increased frequency of schizophrenia and other types of psychiatric morbidity. In this study, we tried to identify a subgroup of schizophrenic patients with deletions in the VCFS region of the long arm of chromosome 22. For that purpose, we screened the records of two major general hospitals for patients with abnormalities characteristic of VCFS, such as cardiac anomalies and cleft palate, and cross-checked the data with the register of psychiatric hospitalizations in four psychiatric hospitals. Of the 24 patients that qualified, only seven patients could be studied. An additional eight schizophrenic inpatients were ascertained clinically, based on a working VCFS Clinical Scale. FISH studies and molecular analyses, using polymorphic markers from the VCFS region, documented hemizygosity of 22q11 in three out of 15 patients (20.0%). Increased awareness of psychiatrists to signs of VCFS among patients with psychiatric illnesses is encouraged, in order to direct molecular studies effectively. In order to cut down the cost of testing, we suggest screening suspected patients with a single marker, such as D22S941, and to study further only those who have a single electrophoretic band.

Abnormalities, Multiple↗
PubMedDate not supplied

Miller-Dieker syndrome with microdeletion of chromosome 17p13.3: report of one case.

Miller-Dieker syndrome (MDS) consists of lissencephaly, characteristic craniofacial appearance and sometimes other birth defects. Since 1983, it has been shown that most cases of MDS are caused by deletion of chromosome 17p13.3. Herein, we present a case of MDS in which the patient had characteristic craniofacial appearance in addition to lissencephaly. Although routine chromosome study showed a normal karyotype, deletion of chromosome 17p13.3 was suggested by high resolution GTG-banding and confirmed by FISH. About 36% of the cases reported by Dobyns had submicroscopic deletions of chromosome 17p13.3 in spite of normal karyotypes in routine chromosome studies. The high frequency of submicroscopic deletion in Dobyn's cases and our present case strongly suggests that chromosomal studies, including high-resolution banding and molecular genetic approaches such as FISH, are mandatory whenever MDS is suspected in cases of lissencephaly with normal karyotypes in routine chromosomal work-up.

Abnormalities, Multiple↗
PubMed1998

Clinical outcomes of four patients with microdeletion in the long arm of chromosome 2.

We present clinical outcome, through several years of follow-up, of 4 mentally retarded patients, each with a small interstitial deletion in the long arm of chromosome 2, within a region on which clinical reports are infrequent. Our patient 1 was found to have del(2)(q22.3q23.3); patients 2 and 3, del(2)(q23.3q24.2); and patient 4, del(2) (q24.2q31). By comparison of our cases with each other and with those previously published with comparable interstitial deletion, we attempted to identify characteristic clinical findings. Short neck with excessive cervical skin was seen with monosomy of chromosome 2 bands q22.3-q23.3, while hypertrichosis and a peculiar high pitched cry were seen with monosomy of chromosome 2 bands q23.3-q24.2. As suggested by Moller et al. [1984: Hum Genet 68:77-86], a cleft between the first and second toes was seen with monosomy of chromosome 2 bands q24.2-q31. In addition, seizure disorder was present in patients 1 and 4 (with the more proximal and distal deletions, respectively).

Adult↗