Pregnancy in a patient with 47,XX,i(Xq) karyotype.

A phenotypically normal woman with a 47,XX,i(Xq) karyotype is reported. She has had two successful pregnancies monitored by prenatal diagnosis with the delivery of normal offspring. The presence of a structurally abnormal third X chromosome has not demonstrably affected this patient or her reproduction. The importance of the human X and Y chromosomes in sexual differentiation is readily apparent. Patients with anomalies of the X chromosome most frequently have clinical features of Turner's syndrome. Much less clearly defined are patients who possess additional X chromosome material. For example, triple X females are not easily distinguishable from 46,XX females. Only a few cases have been reported of patients who have a 47,XXX karyotype with the third X chromosome being structurally abnormal. This report describes a patient with a 47,XX,i(Xq) (qter leads to cen leads to qter) karyotype.     

Partial trisomy 14q24 leads to qter.

A newborn male with partial trisomy for the distal part of the long arm of chromosome 14 (14q24 leads to qter) is described. The anomaly arose as an adjacent 1 meiotic segregation product from a balanced translocation t(11;14) (q25;q24) in the mother (figure). To our knowledge only one previous case involving the same segment has been reported. The karyotype was confirmed as 46,XY,der(11),t(11;14)(q25;q24) mat.     

Replication banding and molecular studies of a mosaic,unbalanced dic(X;15)(xpter→xq26.1::15p11→15qter)

We present a patient with a chromosomal mosaicism involving the X chromosome. One cell line is 45,X and the other has a de novo paternally derived dicentric X;15 translocation. Her karyotype is therefore 45,X/45,X,dic(X;15)(Xpter→Xq26.1: : 15p11→15 qter) based on G-banding. The presence of 2 centromeres on the derivative X was confirmed by fluorescence in situ hybridization (FISH) and a deletion of Xq26.1→qter was confirmed by polymerase chain reaction (PCR) using DXS52 and DXYS154. Replication banding studies indicate that the derivative X is late replicating. Based on these studies, it is unclear whether inactivation has spread to proximal 15q. The patient has a unique phenotype distinct from Ullrich-Turner or Prader-Willi syndromes, but includes ataxia and language delay which are commonly seen in Angelman syndrome. These findings are contrary to those anticipated since deficiency of paternal genes at 15q12 typically leads to Prader-Willi syndrome. Molecular analysis of PCR-based polymorphisms of chromosome 15 and X indicates that uniparental disomy is not present for the X chromosome or chromosome 15 in either cell line. It is hypothesized that her phenotype results from the interaction of the 2 abnormal genotypes. Each abnormality may be diluted by the mosaicism and, in the derivative X line, by the possible variation among cells of inactivation spreading to chromosome 15. © 1995 Wiley-Liss, Inc.     

Inv dup del(4)(:p14 --> p16.3::p16.3 --> qter) with manifestations of partial duplication 4p and Wolf-Hirschhorn syndrome

An 8-year-old girl with a combination of clinical manifestations of partial duplication 4p and the Wolf-Hirschhorn syndrome was studied. Chromosomal G-banding and FISH analyses showed a 33.2-Mb segment of inverted duplication at 4p14-p16.3 and a 2.8-Mb segment of deletion at 4p16.3-pter (including the Wolf-Hirschhorn syndrome critical region). The chromosomes of the parents were normal. Her karyotype was thus 46,XX, inv dup del(4)(:p14 --> p16.3::p16.3 --> qter) de novo. The inverted duplication deletion was assumed to have arisen through chromatid breakage at 4p16.3, U-type reunion at the breakpoints to produce a dicentric intermediate, breakage of the dicentric to result in a monocentric, and telomere capture/healing of the broken end. Olfactory receptor gene clusters at 4p16.3 were ruled out as an intermediary of the duplication deletion process.     

Unusual chromosomal mosaicism in Wolf‐Hirschhorn syndrome: del(4)(p16)/der(4)(qter‐q31.3::pter‐qter)

We report on the unusual cytogenetic findings in a girl with moderate mental retardation and a mosaic karyotype 46,XX,del(4)(p16)/46,XX,der(4)(qter‐q31.3::pter‐qter). The facial features observed in the child initially did not suggest the diagnosis of Wolf‐Hirschhorn syndrome (WHS), but the distinct facial gestalt became obvious at prepubertal age. Fluorescence in situ hybridization (FISH) analysis with different probes that map to 4p and 4q helped to clarify the karyotype. We discuss the mechanism of appearance of this unusual type of mosaicism, which has not been reported before. © 2001 Wiley‐Liss, Inc.     

Dissociation as probable origin of mosaic 45,XY,t(15;21)/46,XY,i(21q).

A patient is described with some features of Down's syndrome and a 45,XY, t(15;21)(15qter leads to 15p13::21p11 leads to 21qter)/46,XY,i(21)(qter leads to cen leads to qter) karyotype. Two mechanisms are proposed for the origin of the mosaicism, one assuming the dissociation of a translocation (15;21) chromosome already present in the zygote, and the other involving a chromatid translocation in a 46,XY zygote. The possible independent origin of the two cell lines is also considered.     

Partial trisomy 3q due to a de novo translocation t(X;3) (p21;q12)

A patient with several congenital malformations, principally in the face, cardiovascular system and genitalia, was found to have the karyotype 46 ,X,der(X),t,X;3)(Xqter← p21::3ql2-←3qter). A comparison of the clinical and cytogenetical findings with similar cases in the literature led to the conclusion that a partial trisomy 3q is the most likely cause for the symptoms in this patient.     

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

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.     

Phenotype of partial trisomy 8 (p21 leads to qter) in two unrelated patients with de novo translocation.

Two unrelated patients with a de novo partial trisomy 8 (q21 leads to qter) are presented. They had strikingly similar phenotypes, characterised by a wide face with hypertelorism, a broad based nose, malformed ears, micrognathia, and a very short neck. A cleft palate, cardiac defects, and hydronephrosis were present in both patients. The relation between the 8qter syndrome and trisomy 8 (Warkany syndrome) is discussed.     

Cryptic duplication and deletion of 9q34.3 --> qter in a family with a t(9;22)(q34.3;p11.2)

A newborn male was referred for genetic evaluation because of multiple congenital abnormalities. Physical findings included a round face, telecanthus, hypertelorism, a short upturned nose with anteverted nares, small ears, micrognathia, short toes, and congenital heart disease. Chromosome analysis detected a possible deletion of 9qter because of satellite material on 9qter. Delineation by FISH and microarray CGH studies showed 46,XY,der(9)t(9;22)(q34.3;p11.2). The mother and maternal grandfather had a balanced t(9;22)(q34.3;p11.2) rearrangement. Also, the maternal great-aunt of the propositus was found to have a duplication of 9q34.3 --> qter. FISH was required to delineate her karyotype, which was 46,XX.ish der(22)t(9;22)(q34.3;p11.2). This maternal great-aunt and one of her daughters (cytogenetics not done) have a relatively normal phenotype, only reporting mild learning disabilities in school. Since the 22p material involved in this rearrangement is clinically irrelevant, this report describes an individual with a pure deletion of 9q34.3 --> qter and another with a pure duplication of 9q34.3 --> qter.     

一例母源性46,Y,der(X)t(X;Y)(p22;q11)染色体非平衡易位患儿的遗传学分析

目的对1例临床表征为身材矮小、鼻根部内陷、双侧隐睾、智力低下患儿进行遗传学分析,探讨该染色体结构异常与临床表征之间的关系。方法应用G显带染色体核型分析及染色体微阵列分析(chromosomal microarray analysis,CMA)技术对患儿进行遗传学检测,并对其父母进行外周血染色体核型分析。结果G显带分析结果显示患儿染色体核型为46,Y,der(X)t(X;Y)(p22;q11),mat。CMA检测结果提示患儿X染色体短臂Xp22.33p22.31存在约8.3 Mb片段缺失,Y染色体长臂Yq11.221qter存在约43.3 Mb片段重复。其父亲染色体核型正常,母亲染色体核型结果为46,X,der(X)t(X;Y)(p22;q11)。结论患儿携带母源性der(X)t(X;Y)(p22;q11)染色体非平衡易位,携带者的表型与其性别以及X染色体缺失片段的大小和位置密切相关。男性携带者智力障碍、生长发育落后等异常表型较女性更为严重。     

Isodicentric Y (p11.32) chromosome in an infant with mixed gonadal dysgenesis

Among the structural abnormalities affecting the human Y chromosome, dicentric chromosomes are the most common. A wide spectrum of phenotypes of patients with a dicentric Y chromosome exists, ranging from almost males through mixed gonadal dysgenesis to females with Turner syndrome. Here, we describe an infant with mixed gonadal dysgenesis and mosaic karyotype 45,X/46,X,idic(Y)(qter-->p11.32:p11.32-->qter)/47,X,+2idic(Y) (qter-->p11.32:p11.32-->qter)/47,XYY. This was demonstrated by fluorescence in situ hybridization (FISH) analysis with whole Y chromosome painting (WCP-Y) probe. Molecular studies were performed on genomic DNA extracted from peripheral blood lymphocytes. To examine the sex determined region (SRY), azoospermia factor (AZF) region and deletion in azoospermia gene (DAZ), polymerase chain reaction (PCR) analyses were done with sequence-tagged site (STS) primers of 20 loci along the Y chromosome (SRY, DYS271, DYS148, DYS273, KALY, DYS212, SMCY, DYS215, DYS218, DYS219, DYS221, DYS223, DYS224, DYF51S1, DYS236, DAZ, DYS240), and all tested loci were found positive. Because of the possibility of a mutation in the SRY gene, we analyzed the PCR fragment by DNA sequencing and did not observe any mutation or nucleotide alteration. We present detailed molecular-cytogenetic characterization of a patient with idic(Y)(p11.32), and results are discussed with the previously described patients. As far as we know, this is the fifth report of a 46,X, idic(Y)(p11.32) karyotype and the first presentation with mixed gonadal dysgenesis and isodicentric Y. Since the correlation between phenotype and karyotype is not yet well defined, the clinical reports will be helpful in defining the phenotypic range of this chromosomal abnormality.     

Multiple congenital anomalies,brain hypomyelination,and ocular albinism in a female with dup(X)(pter→q24::q21.32→qter) and random X inactivation

We report on an 18-month-old girl with multiple congenital anomalies (prominence of the metopic suture, fine hair, club foot, absence of the 12th rib, brachydactyly) and severe mental retardation. The funduscopic examination showed diffuse retinal hypopigmentation. Brain magnetic resonance image (MRI) showed signs of diffuse hypomyelination. On cytogenetic and molecular evidence, the karyotype was 46,X,dirdup(X) (pter→q24::q21.32→qter). The duplication of the PLP gene, involved in Pelizaeus-Merzbacher disease, was confirmed by fluorescent in situ hybridization (FISH). Both cytogenetic and molecular studies on the X chromosome inactivation status indicated a random pattern in lymphocytes and fibroblasts. This patient appears to be the first case of a female bearing a large duplication of Xq with a random X inactivation. The phenotype of this patient is compared to that of previously reported cases with Xq duplication. Am. J. Med. Genet. 72:329–334, 1997. © 1997 Wiley-Liss, Inc.     

Trisomy 6qter

A previously reported patient with trisomy for the distal part of 6q was shown by R-banding to be trisomic for 6q26qter, due to a t(6;22)(q26;p12) mat. Altogether nine patients with 6qter trisomy have been reported. The main features of the 6qter trisomy syndrome are: severe mental and growth retardation; acrocephaly and brachycephaly; a carp-shaped mouth; micrognathia; a very short neck with unusual anterior webbing; joint contractures; the absence of severe inner organ malformations; and survival into adulthood.     

Inherited interstitial del(Xp) with minimal clinical consequences: with a note on the location of genes controlling phenotypic features.

In a routine cytogenetic investigation of the outpatients of a hospital for the mentally retarded, a 26-year-old women with a presumptive interstitial deletion of the short arm of one of the X chromosomes was found. The same aberration was found in her phenotypically normal mother and in one of her four sisters, all phenotypically normal. By GTG- and QFQ-banding methods, the deletion was interpreted to involve the entire band Xp21 and adjacent parts of p11 and p22. The karyotype is written 46,X,del(X)(pter leads to p22::p11 leads to qter). By autoradiography and Bud R acridine orange technique, the deleted X was the late replicating one in all three affected persons. The deletion apparently causes shortness of stature but no other phenotypic symptoms or signs. Hence a gene or genes controlling stature is located in band Xp21 or regions immediately adjacent to this band. Since the absence of this region does not cause streak gonads, it does not contain genes controlling the formation of the ovaries. This appears to be the first example of a heritable chromosome deletion compatible with a normal phenotype and reproduction.     

Trisomy 10qter confirmed by in situ hybridisation.

We report a boy with multiple congenital anomalies compatible with trisomy for the distal region of the long arm of chromosome 10 and a male karyotype with one 18p+. In situ hybridisation with a cDNA for ornithine aminotransferase (OAT), whose locus maps to 10q26, confirmed the clinical suspicion of distal trisomy 10q. Subterminal localisation of the labelling signals on chromosome 10 and on the der(18) indicated the localisation of the OAT locus in the proximal part of 10q26. Two clusters of labelling signals were also found on the pericentromeric and proximal portion of the X chromosome short arm, thus confirming the presence in this region of two non-adjacent OAT pseudogenes. The phenotypic similarities of this patient to previously reported cases provide further support for the delineation of trisomy 10qter as a specific, clinically recognisable syndrome.     

De novo interstitial deletion del(1)(p21p32).

A girl aged 14 years 9 months, overweight, with severe psychomotor retardation, short stature, a sheep-like face, malformed ears, skeletal and dermatoglyphic abnormalities, and partial deletion of the short arm of chromosome 1 is presented. The karyotype was 46,XX,del(1)(qter to p22::p32 to pter).     

A familial Xp+ chromosome, dup (Xq26.3-->qter).

A maternally transmitted Xp+ chromosome was associated with an abnormal phenotype, including developmental delay and short stature, in two male cousins and their 12 year old aunt. The respective mothers were not mentally impaired but had short stature. The G banding pattern identified the extra chromosome segment as a repeat of Xq26.3-->qter attached to an apparently intact Xp22.3 sub-band, so the Xp+ chromosome may be described as rea(X)(Xqter-->p22.3::Xq26.3-->Xqter). The rearranged chromosome was late replicating in 97 to 100% of the metaphases in the mothers but it was early replicating in 43% of the lymphocytes in the mentally defective female (n = 100 cells/subject). Fluorescence in situ hybridisation using X and Y chromosome paints, as well as cosmids A and 1A1 specific for loci within Xq28, confirmed both the identity of the extra segment and the entirety of the Xp pseudoautosomal region. Therefore, the phenotypic consequences in this family can be related to the Xq26.3-->qter functional disomy allowing for the effects of X inactivation in the female carriers.     

A woman with an apparent non-mosaic 45,X delivered a 46,X,der(X) liveborn female

A liveborn female with a phenotype suggestive of Down syndrome is reported. Cytogenetic lymphocyte analysis showed a 46,X der(X) karyo-type. Fluorescence in situ hybridization (FISH) with a biotinylated probe specific for chromosome 21 showed no signal on the der(X). This marker was homogeneously painted using a specific probe for X chromosome. In addition, FISH analysis detected telomeres on the rearranged X. Therefore, the proband's karyotype was revaluated as 46,X,del(X) (pter p22.2::p11.3 qter). Cytogenetic analysis of 150 lymphocytes in the mother disclosed a homogeneous 45,X karyotype. FISH analysis of interphase nuclei using the X chromosome painting probe showed two domains of different sizes in 0.8% of cells. This led us to study further metaphases in the mother. In one out of 450 metaphases scored, after FISH with the X chromosome painting probe, the del(X) was observed, confirming that the rearranged X chromosome found in the newborn had segregated from a 45,X/46,X,del(X) mother.