Application of personal computer to an analysis of small de novo chromosomal insertion: a case of de novo 3q2 trisomy with ins(8;3)

To identify the origin of a small inserted segment in a de novo 8p+ chromosome, an originally programmed computerized database for chromosomal aberration syndromes was utilized. The system selected 3q2 trisomy and 10q2 trisomy as candidates. As a result of a careful comparison of several high-resolution banding patterns among chromosomes 3, 10 and the inserted segment, her karyotype was disignated as: 46,XX,-8,+der(8), inv ins(8;3)(p21.1;q26.32q24) de novo. A small segment from 3q24 to 3q26.32 was trisomic, and invertedly inserted into the short arm of chromosome 8. This computerized database was considered to be useful for analyses of the small de novo inserted chromosomal segment.     

Partial trisomy 1q. A nonrandom primary chromosomal abnormality in myelodysplastic syndromes?

Cytogenetic and clinical data of 11 patients with de novo myelodysplastic syndromes and partial or total trisomy of the long arm of chromosome 1 are presented. In eight of these patients trisomy 1q was the sole karyotypic change and therefore can be classified as a primary chromosome anomaly. A remarkably young median age of 36.5 years was noticed in this patient group.     

Endocrine abnormalities in a patient with partial trisomy 4q.

Partial trisomy of the long arm of chromosome 4, usually resulting from a familial segregation of a balanced translocation, has been described in a number of patients. This report describes the genetic and endocrine findings in a 16 year old 46,XY,12q+ mentally retarded male. The banding pattern of the extra chromatin material from this de novo unbalanced translocation shows that the distal segment of the long arm of chromosome 4 is involved. Comparison of the clinical features in this patient with cases of partial trisomy 4q previously reported support the cytogenetic evidence for this translocation involving the distal portion of 4q. Endocrine data suggested an end-organ resistance, characterised by extreme hyperinsulinaemia, primary hypothyroidism, and hypergonadotrophic hypogonadism associated with no signs of autoimmunity. To our knowledge, no endocrine evaluation has been previously reported in patients with partial trisomy 4q.     

Phenotypic manifestation in a child with 46,X,der(X)t(X;1)(q24;q31.1)

We report on a 5-year-old girl with multiple congenital anomalies, developmental delay, and a de novo unbalanced translocation between chromosomes X and 1[46,X,der(X)-t(X;1)(q24;q31.1)] resulting in partial trisomy 1q and partial monosomy Xq. The karyotype shows inactivation of the abnormal X chromosome. The translocated portion of 1q remains active in the tissues studied. This is the third case report with partial trisomy 1q and partial monosomy Xq. However, it is the first with specific breakpoints at 1q31.1 and Xq24.     

Trisomy 20q caused by interstitial duplication 20q13.2: clinical report and literature review

We report on a 3-year-old boy with moderate developmental delay, abnormal craniofacial features and ventricular septal defect resulting from trisomy of the long arm of chromosome 20. The cytogenetic defect consists of a de novo isolated interstitial duplication in distal 20q [dup(20)(q13.2q13.2)]. The duplication was detected by comparative genomic hybridization (CGH) and confirmed by array CGH. Other cases of comparable trisomies are reviewed. This new case further delineates the recognizable phenotype of trisomy 20q13 --> 20qter and highlights the relevance of CGH for the detection of such rearrangements.     

Duplication of (2)(q11.1‐q13.2) in a boy with mental retardation and cleft lip and palate: Another clefting gene locus on proximal 2q?

A 4‐year‐old boy with left cleft lip and cleft palate, multiple minor anomalies and developmental delay revealed an abnormal chromosome 2 with enlarged proximal long arm, de novo, in his karyotype. Fluorescence in situ hybridization with a chromosome 2 library and band‐specific YACs confined the duplicated segment to 2q11.1‐q13.2 and indicated a direct tandem duplication due to unbalanced crossover between chromatids. © 2002 Wiley‐Liss, Inc.     

Additional case of de novo interstitial deletion del(17)(q21.3q23) and expansion of the phenotype

Khalifa MM, MacLeod PM, Duncan AMV. Additional case of de novo interstitial deletion del(17)(q21.3q23) and expansion of the phenotype. Clin Genet 1993: 44: 258–261. © Munksgaard, 1993
A child with multiple congenital abnormalities and a de novo interstitial deletion of the long arm of chromosome 17 is reported. This is the third case reported with this chromosome abnormality. The three cases present a peculiar phenotype, which is probably specific to the deletion.     

First report of a partial trisomy 3q12-q23 de novo--FISH breakpoint determination and phenotypic characterization

We present a 1-year-old boy with mild mental retardation, postnatal growth retardation, and facial dysmorphisms such as frontal bossing, laterally accentuated bushy eyebrows, deep set eyes with long lashes, hypertelorism, and a broad nasal bridge. Except for hip dysplasia, no congenital malformations were detected. By conventional cytogenetics a derivative chromosome 3 de novo was diagnosed which was identified as tandem dup(3)(q12q23) by fluorescence in situ hybridization (FISH) applying arm specific paints and eight different YAC-probes. The duplicated segment lies proximally from the reported dup(3q) syndrome critical region, thus explaining the absence of characteristic phenotypic features of dup(3q) syndrome. To our knowledge this is the first report of a patient with pure trisomy of this proximal region of the long arm of chromosome 3.     

Attenuated phenotype in a child with trisomy for 1q due to unbalanced X;1 translocation [46,X,der(X),t(X;1)(q28;q32.1)

We report a case of an X;1 translocation in a 9-month-old female infant with mild dysmorphic features and developmental delay. High-resolution chromosome analysis revealed a de novo, unbalanced translocation between chromosomes X and 1 [46,X,der(X),t(X;1)(q28;q32.1)]. Breakpoints on the derivative X and the size of the translocated segment have been defined by fluorescence in situ hybridization (FISH) with Xq and 1q specific probes. The rearrangement in this patient results in monosomy for Xq28-qter and trisomy for 1q32.1-qter. Replication studies demonstrated late replication of the derivative X in 80% of the observed cells, with the exception of 20% of the cells where X inactivation failed to spread into the translocated 1q segment. Patients with pure trisomy for the distal segment of 1q present a considerably more severe phenotype compared to that seen in our patient, including facial dysmorphisms, urogenital and cardiac anomalies. We suggest that the absence of many of the characteristic features for trisomy 1q in our patient, may reflect a mosaic pattern of inactivation of the translocated autosomal segment on the derivative X chromosome.     

Duplication 2 (q11.2-q21): a previously unreported abnormality

A 7 year old boy is described with moderate learning disability, facial dysmorphism, and a de novo duplication of chromosome 2 (q11.2-q21). There are few published reports of proximal 2q duplication, and none reporting direct de novo duplication for this exact region.     

Complete trisomy 5p owing to de novo translocation t(5;22)(q11;p11) with isochromosome 5p associated with a familial pericentric inversion of chromosome 2, inv 2(p21q11).

A boy with a de novo translocation (5;22) and isochromosome 5p associated with a pericentric inversion of chromosome 2 (p21q11) is described. The pericentric inversion was also present in the mother. The main clinical features of the 'complete trisomy 5p' syndrome were present in the proband.     

De novo interstitial direct duplication 1(q23.1q31.1) in a fetus with Pierre Robin sequence and camptodactyly

Interstitial duplications of chromosomal region 1q are rarely seen. We report the first prenatal diagnosis of pure partial trisomy 1q. The fetus was karyotyped for polyhydramnios, micrognathia, and flexion of fingers of both hands. Conventional and molecular cytogenetics showed a de novo direct duplication of the chromosomal region 1q23.1q31.1 leading to a partial trisomy 1q. At autopsy, the fetus showed Pierre Robin sequence (PRS) and camptodactyly. The main histological finding was a decreased number of motoneurons with apoptotic features in the anterior horn of the spinal cord. A literature review and our observations suggest that genetic material mapping to chromosome 1q25 could be responsible for PRS with distal arthrogryposis when this is in triple dose.     

A de novo 6q11—q15 duplication investigated by chromosome painting

A de novo interstitial duplication of the 6q11—q15 chromosome region, confirmed by the application of a chromosome 6 painting probe, was observed in a patient with craniofacial dymorphism, psychomotor retardation, cryptorchidism and hypospadias. Despite the publication of several cases showing partial trisomy 6q, to our knowledge the duplication of the proximal region q11-q15 has not previously been reported.     

Maternal origin of a unique extra chromosome,der(9)(pter→q13::q13→q12:) in a girl with typical trisomy 9p syndrome

We report on a girl with the typical trisomy 9p syndrome who had an additional E‐sized metacentric chromosome. On the basis of GTG‐ and CBG‐banding, her karyotype was considered to be 47,XX,+der(9)(pter→q13::q13→q12:) de novo. Results of a fluorescence in situ hybridization study using a chromosome 9‐specific painting probe were compatible with this cytogenetic interpretation. Molecular analyses of six highly polymorphic dinucleotide repeat loci on the short arm and the proximal long arm of chromosome 9 demonstrated that the girl inherited one allele from her father and two identical or different alleles from the mother. We speculated that the extra chromosome may have resulted from either nondisjunction of chromosome 9 followed by a U‐type exchange and a crossing‐over between different sister chromatids during maternal meiosis I and subsequent breakage and malsegregation during meiosis II, or nondisjunction during meiosis II followed by isochromosome formation in one of the two maternal chromosomes 9 and subsequent breakage. © 2001 Wiley‐Liss, Inc.     

Subtelomeric monosomy 11q and trisomy 16q in siblings and an unrelated child: molecular characterization of two der(11)t(11;16)

We report here three children with a der(11)t(11;16), two sibs (patients 1 and 2) having inherited a recombinant chromosome from a maternal t(11;16)(q24.3;q23.2) and a third unrelated child with a de novo der(11)t(11;16)(q25;q22.1), leading to partial monosomy 11q and trisomy 16q. Fluorescent in situ hybridization (FISH) using bacterial artificial chromosome (BAC) clones and array‐CGH were performed to determine the breakpoints involved in the familial and the de novo rearrangements. The partial 11 monosomy extended from 11q24.3 to 11qter and measured 6.17–6.21 Mb in Patients 1 and 2 while the size of the partial 11q25‐>qter monosomy was estimated at 1.97–2.11 Mb for Patient 3. The partial 16 trisomy extended from 16q23.2 to 16qter and measured 8.93–8.95 Mb in Patients 1 and 2 while the size of the partial 16q22.1‐>qter trisomy was 20.82 Mb for Patient 3. Intraventricular hemorrhage and transitional thrombocytopenia were found in both sibs but not in the third patient. The FLI1 gene, which is the most relevant gene for thrombocytopenia in Jacobsen syndrome, was neither deleted in family A nor in Patient 3. We suggest that a positional effect could affect the FLI1 expression for these two sibs. Deafness of our three patients confirmed the association of this anomaly to 11q monosomy and tended to confirm the hypothetic role of DFNB20 in Jacobsen syndrome hearing loss. Both sibs shared most of the features commonly observed in Jacobsen syndrome, but not the third patient. This confirmed that terminal 11q trisomy spanning 1 to 1.97–2.11 Mb is not associated with a typical Jacobsen syndrome. © 2011 Wiley‐Liss, Inc.     

Case of partial trisomy 2q3 with clinical manifestations of Marshall-Smith syndrome.

We describe a girl with physical anomalies, accelerated skeletal maturation, failure to thrive, and respiratory difficulties consistent with a diagnosis of Marshall-Smith syndrome (MSS). Chromosome analysis showed an inverted duplication of chromosome 2 [46,XX,inv dup(2)(q37q32) de novo] identified by G banding and confirmed by FISH. Several cases of trisomy 2q3 have been reported and established a syndrome, but the present case is the first to be associated with accelerated skeletal maturation and a clinical picture resembling MSS. This raises the possibility that the cause of MSS involves the q3 region of chromosome 2. Few reports of MSS include study of the karyotype, although the chromosomes were apparently normal in those cases where they have been examined. We suggest that karyotyping be undertaken with particular attention to the 2q3 region in patients with suspected MSS. It also would be prudent to assess bone age in all children with trisomy 2q.     

Inverted tandem (“mirror”) duplications in human chromosomes: Inv dup 8p, 4q, 22q

We have studied 4 patients with inverted tandem duplications of parts of chromosomes, a hitherto rarely identified from of a structural rearrangement involving a single chromosome in man. In Patients 1 and 2, the duplication involved parts of the short arm of chromosome 8 (regions 8p 12→8p23 and 8p21→8p23, respectively). Both patients manifested certain characteristics of the mosaic trisomy 8 syndrome. Elevated levels of glutathione reductase (GSR) in their erythrocytes supported the interpretation of a partial duplication of chromosome 8 and indicated a regional localization for the GSR gene locus. In Patient 3, the distal half of the long arm of chromosome 4 was duplicated (region4q26→4q35). Clinical evidence supported this interpretation, as Patient 3 resembled phenotypically the 13 reported cases with duplication of the distal 4q. The cytogenetic findings in Patient 4 suggested a possibly inverted duplication of 22q. The clinical correlation was less convincing due to the lack of a well-defined phenotype for trisomy 22. These chromosome aberrations had occurred de novo in all 4 cases. Although they involved different chromosomal regions, they might well have arisen by the same mechanism. Possible modes of origin that are discussed in detail include unequal exchange between homologous chromosomes, between chromatids of 1 chromosome or between strands of 1 DNA duplex.     

Detection of a de novo duplication of 1q32-qter by fluorescence in situ hybridisation in a boy with multiple malformations: further delineation of the trisomy 1q syndrome.

We report a dysmorphic boy with a de novo partial trisomy 1q. The boy has microcephaly, bilateral cleft lip and palate, low set and dysmorphic ears, brain anomalies, pulmonary stenosis, duodenal obstruction, dysplastic kidneys, and bifid thumbs. The trisomic segment 1q32-qter is duplicated with an inverted insertion at 1p36.3. The aberration was initially detected at amniocentesis and confirmed and defined by GTG banding, chromosome microdissection, and FISH on postnatal blood samples. The parents had normal karyotypes. De novo partial duplications of chromosome 1q have rarely been reported. Comparison of our patient with other published pure trisomy 1q cases showed similarities which allowed the further delineation of the trisomy 1q syndrome.     

Clinical and molecular cytogenetic characterization of two patients with partial trisomy 1q41-qter: further delineation of partial trisomy 1q syndrome.

We report the clinical and molecular cytogenetic characterization of two patients with partial trisomy 1q. The first patient is a currently 11-year-old female proposita with a de novo unbalanced translocation 46,XX,der(8)(8qter-8p23.3::1q41-1qter), leading to a partial trisomy 1q41-qter and a partial monosomy for 8p23.3-pter. The most prominent clinical features of the girl are a triangular face, almond-shaped eyes, low-set ears, short stature with relatively long legs, and mild psychomotor retardation. To our knowledge, the cytogenetic aberration in this girl is the most proximal partial trisomy 1q leading to a mild phenotype. Recently, we identified a second patient with a similar partial trisomy 1q combined with a cri du chat syndrome caused by a de novo unbalanced translocation 46,XX,der(5)(5qter-5p13.1::1q41-1qter). Comparison of the phenotype of the two girls as well as with already published trisomy 1q cases was performed, and fluorescence in situ hybridization probes from selected YACs were used to delineate the extent of the partial trisomy in more detail.