FISH characterization of a supernumerary r(1)(::cen-->q22::q22-->sq21::) chromosome associated with multiple anomalies and bilateral cataracts.

We describe the case of a 15-year-old girl with multiple congenital anomalies, dysmorphic features, severe kyphoscoliosis, growth and mental retardation, and the absence of speech, in whom 35% of the cells carried a supernumerary ring chromosome 1. Fluorescence in situ hybridization (FISH) analysis using YAC/BAC clones spanning the region from 1p13 to 1q21 made it possible to determine the genomic content and structure of the ring(1), which was found to consist of the cytogenetic bands 1q21-22. A complex structure was delineated in the ring chromosome with a partial inverted duplication delimited by markers WI-7732 and WI-607, with WI-7396 and WI-8386 being the boundaries of the single copy segment. Comparison of the clinical signs of other patients with mosaic r(1) reported in the literature allowed the identification of a patient sharing a number of clinical signs including cataracts. Given that mutations of the GJA8 gene encoding connexin 50 (Cx50) and mapping to 1q21 have been associated with the presence of cataracts, it is possible that a gain in copy number or a rearrangement of GJA8 may contribute to cataractogenesis.     

Familial dup(5)(q15q21) associated with normal and abnormal phenotypes

We studied a familial dup(5q) present in a phenotypically normal father and his monozygotic twin daughters with different abnormal phenotypes. High-resolution chromosome analysis suggested that the duplicated segment was of region q15-21, which seems to be the smallest dup(5q) reported thus far. This dup(5q) was confirmed by fluorescence in situ hybridization with a chromosome 5 painting library and 5q cosmid clones. The presence of the dup(5q) in a normal father suggested that the duplication itself may be harmless. The anomalies in the twins may be due to processes other than this chromosome change. Am. J. Med. Genet. 75:75–77, 1998. © 1998 Wiley-Liss, Inc.     

Precise mapping of a de novo duplication 18(q21→q22) utilizing cytogenetic,biochemical, and molecular techniques

We describe the first de novo inverted duplication of 18q. Due to the difficulty of identifying de novo chromosome abnormalities based solely on cytologic studies, precise definition of the 18q duplication was attempted by integrating cytogenetic and clinical findings with biochemical and molecular dosage studies. The combined results demonstrated that the proposita had a duplication of 18q21→q22 with a karyotype of 46,XX,–18,+inv dup(18) (pter→q12.1::q22→q21::q12.1→qter). The duplication of this specific chromosome region does not result in the typical 18 phenotype, supporting the hypothesis that various loci on chromosome 18 may interact to produce the manifestations of this syndrome. © 1993 Wiley-Liss, Inc.     

CHARGE association in a child with de novo inverted duplication (14)(q22 → q24.3)

We report on a 4-1/2 year old girl with apparent CHARGE association who had a de novo inverted duplication (14)(q22 → 24.3), iris colobomas, ventricular septal defect, soft tissue choanal atresia, intellectual impairment, growth retardation, sensorineural deafness, apparently low set ears, and upslanting palpebral fissures. Family history was unremarkable and parental chromosomes were normal. Similarities between this and previously reported cases of 14q duplication suggest that a locus for a gene or genes causing some of the anomalies of CHARGE association may reside in the region 14q22 to 24.3. © 1995 Wiley-Liss, Inc.     

FISH characterization of two supernumerary r(1) associated with distinct clinical phenotypes

Only a few reports on supernumerary r(1) chromosomes associated with a clinical phenotype have been published. We describe two unrelated patients with congenital malformations and developmental delay who were found to have a de novo supernumerary r(1) in 50% (Case 1) and 80% (Case 2) of the examined cells. Conventional cytogenetic techniques (QFQ, CBG, and DA-DAPI), complemented by fluorescence in situ hybridization studies using alpha satellite probes, showed that both small marker chromosomes (SMCs) primarily consisted of the centromere and heterochromatin of chromosome 1, a conclusion that was also supported by chromosome 1 painting. In an attempt to establish phenotype-genotype correlations, a further investigation was performed using YACs mapped to the chromosome 1 pericentromeric region. A fluorescent signal was evident after hybridization with Y934G9 (1q21) in Case 1 and Y959C4 (1p11.1-12) in Case 2. Partial trisomy of unique sequences flanking pericentromeric sequences is shown to underlie the clinical phenotype in both patients. This evidence should be taken into account when SMCs are ascertained, particularly in prenatal diagnosis. Am. J. Med. Genet. 84:377–380, 1999. © 1999 Wiley-Liss, Inc.     

Involvement of a palindromic chromosome 22-specific low-copy repeat in a constitutional t(X; 22)(q27;q11)

Segmental duplications or low-copy repeats (LCRs) on chromosome 22q11 have been implicated in several chromosomal rearrangements. The presence of AT-rich regions in these duplications may lead to the formation of hairpin structures, which facilitate chromosomal rearrangement. Here we report the involvement of such a low-copy repeat in a t(X;22) associated with a neural tube defect. Molecular analysis of the chromosomal breakpoints revealed that the chromosome 22 breakpoint maps in the palindromic non-AT-rich NF1-like region of low-copy repeat B (LCR-B). No palindromic region was encountered near the breakpoint on chromosome X. Our findings confirm that there is no single mechanism leading to translocations with chromosome 22q11 involvement. Because LCR-B does not contain genes involved in neural tube development, we believe that the gene responsible for the observed phenotype is most likely localized on chromosome X.     

Inv dup del (1)(pter→q44::q44→q42:) with the classical phenotype of trisomy 1q42–qter

We report on a girl with a trisomy 1q42–q44 due to an inverted duplication of this region, associated with a terminal deletion of the long arm of the rearranged chromosome 1. Both the large duplication (more than 30 cM) and the small deletion were detected by FISH. Complete karyotype was: (46,XX, inv dup(1)(q44q42).ish(dup del 1)(q44q42)(D1S446×2, D1S423×2, tel1q‐). The phenotype of the patient is characterized by macrocephaly with prominent forehead, downslanting palpebral fissures, micrognathia, and psychomotor retardation. All these clinical features are the same as observed for the typical trisomy 1q42–qter syndrome. The phenotypic effects of the inversion and the terminal deletion of 1q in addition to the trisomy are discussed here. © 2001 Wiley‐Liss, Inc.     

Refined FISH characterization of a de novo 1p22–p36.2 paracentric inversion and associated 1p21–22 deletion in a patient with signs of 1p36 microdeletion syndrome

We report on a 10‐year‐old boy presenting with obesity, moderate mental retardation, large anterior fontanelle at birth, mild physical anomalies including mid‐face hypoplasia, deep‐set eyes, long philtrum, and small mouth. He was found to carry a paracentric inversion inv(1)(p22p36.2) associated with a 10 cM deletion at the proximal breakpoint. By YAC FISH, the boundaries of the deletion were established at IB1028 (1p21) and WI‐5166 (1p22) STSs contained in YACs 781E8 and 954F6, respectively. This large region, covering about 10 cM, contains the COL11A1 and AMY2B genes, whose haploinsufficiency does not seem to contribute significantly to the clinical phenotype. On the other hand, the patient's clinical manifestations, also including visual problems and moderate mental retardation, are those typically observed in the 1p36 deletion syndrome. Refined mapping of the telomeric 1p36.2 inversion breakpoint was obtained by FISH of a PAC contig constructed to encompass this subinterval of the 1p36 microdeletion syndrome region. PACs 1024B10 and 884E7 were found to span the breakpoint, suggesting that the clinical signs of the 1p36 microdeletion syndrome might be due to disruption of a sequence lying at 1p36.2. © 2001 Wiley‐Liss, Inc.     

Duplication 8q syndrome due to familial chromosome ins(10;8)(q21;q212q22)

We describe a kindred in which an ins(10;8)(q21;q212q22) chromosome rearrangement has been segregating for at least four generations. The risk for balanced carriers to have offspring with duplication of 8q212→8q22 is about 0.31. Individuals with unbalanced chromosomes are mildly to moderately mentally retarded and have a similar unusual appearance. Other manifestations include highly arched or cleft palate (8/9), micrognathia (6/9), sloped shoulders (4–6/9), convulsions (4/9), camptodactyly (3/9), pectus excavatum (2/9), elbow contractures (1/9), and postaxial polydactyly (1/9). The appearance and habitus resemble the mosaic trisomy 8 syndrome, although other anomalies of mosaic trisomy 8, such as vertebral, patellar, and renal defects, were not demonstrated.     

Thymus deficiency in an infant with a chromosome t(18;22)(q12.2;p11.2)pat rearrangement

The finding of an unbalanced t(18;22)pat chromosome rearrangement in a boy with multiple anomalies including apparent absence of the thymus is described. The observation is of interest because of the reported association of chromosome 22 rearrangements with the DiGeorge sequence. In contrast to previous reports of this association, the deletion involving chromosome 22 is confined to the short arm.     

Tetrasomy 15q25.3 → qter resulting from an analphoid supernumerary marker chromosome in a patient with multiple anomalies and bilateral Wilms tumors

We describe a girl who had been followed since birth for apparent Shprintzen‐Goldberg syndrome (SGS), with macrosomia, long fingers and toes, and craniosynostosis, and presented at 4 years of age with bilateral Wilms tumors (also called nephroblastoma). Cytogenetic analysis of her peripheral blood revealed a de novo supernumerary marker chromosome. This stable marker chromosome is present in 19 of 20 lymphocytes analyzed, as well as in all 40 tumor cells (20 from each tumor) studied. Classical and molecular cytogenetic studies indicate that the marker is derived from an inverted duplication of chromosome 15q25.3 → qter and contains a neocentromere. The presence of this marker chromosome in our patient results in tetrasomy 15q25.3 → qter. The relationship between her genotype and phenotype are discussed in light of genes, including IGF1R and FES, mapped to the aneusomic segment. © 2002 Wiley‐Liss, Inc.     

Pediatric acute myeloid leukemia with t(7;21)(p22;q22)

The t(7;21)(p22;q22) resulting in RUNX1‐USP42 fusion, is a rare but recurrent cytogenetic abnormality associated with acute myeloid leukemia (AML) and myelodysplastic syndromes. The prognostic significance of this translocation has not been well established due to the limited number of patients. Herein, we report three pediatric AML patients with t(7;21)(p22;q22). All three patients presented with pancytopenia or leukopenia at diagnosis, accompanied by abnormal immunophenotypic expression of CD7 and CD56 on leukemic blasts. One patient had t(7;21)(p22;q22) as the sole abnormality, whereas the other two patients had additional numerical and structural aberrations including loss of 5q material. Fluorescence in situ hybridization analysis on interphase cells or sequential examination of metaphases showed the RUNX1 rearrangement and confirmed translocation 7;21. Genomic SNP microarray analysis, performed on DNA extracted from the bone marrow from the patient with isolated t(7;21)(p22;q22), showed a 32.2 Mb copy neutral loss of heterozygosity (cnLOH) within the short arm of chromosome 11. After 2‐4 cycles of chemotherapy, all three patients underwent allogeneic hematopoietic stem cell transplantation (HSCT). One patient died due to complications related to viral reactivation and graft‐versus‐host disease. The other two patients achieved complete remission after HSCT. Our data displayed the accompanying cytogenetic abnormalities including del(5q) and cnLOH of 11p, the frequent pathological features shared with other reported cases, and clinical outcome in pediatric AML patients with t(7;21)(p22;q22). The heterogeneity in AML harboring similar cytogenetic alterations may be attributed to additional uncovered genetic lesions.     

Direct duplication of chromosome 1, dir dup(1)(p21.2 → p32) in a Bedouin boy with multiple congenital anomalies

Here we describe a Bedouin boy with a de novo duplication of 1p and multiple congenital anomalies. He had microcephaly, convergent squint, anteverted nostrils, malformed ears, micrognathia, hypoplasia of the terminal phalanges, clinodactyly of 5th fingers, simian creases, left inguinal hernia, cryptorchidism, and severe postnatal growth retardation. Our clinical findings are compared with those of previous reports of duplication involving chromosome 1p.     

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. © 2001 Wiley‐Liss, Inc.     

Tandem duplication (1) (q11 → q22) in a male infant with multiple congenital malformations

An inverted tandem duplication of 1q11-q22 was found in a male infant with severely retarded psychomotor development, growth retardation, and multiple congenital malformations. Trisomy for this segment of chromosome 1 has not been previously reported.     

5-azacytidine treatments in the characterization of a t(1;21)(q12;q22) carrier karyotype

A 46,XX,t(1;21)(q12;q22) carrier was ascertained because of two abortions. The non-reciprocal nature of the rearrangement was demonstrated in 5-azacytidine treated preparations with highly decondensed and somatically paired heterochromatic regions.     

Dup(lq)(q42→qter) syndrome: Case report and review of literature

We report on a patient with primordial growth retardation, mental retardation, and minor anomalies (triangular face, open sagittal suture, frontal bossing, telecanthus, upturned nose, micrognathia, and small mouth with downturned corners). The diagnosis of Russell-Silver syndrome (RSS) had been considered but was abandoned when cytogenetic evaluation showed a partial trisomy lq or duplication lq (46,XY,15, + der(15)t(l;15)(q42;qter). Data from another 5 reports of dup(l)(q42→qter) do not allow delineation of a typical syndrome. However, individuals with dup(lq), del(15q), and Russell-Silver syndrome share common manifestations (i.e., low birth weight, growth retardation, triangular face, low set/abnormal ears, micrognathia, renal anomalies). © 1993 Wiley-Liss, Inc.     

Interstitial deletion of 8q21→22 associated with minor anomalies,congenital heart defect,and Dandy-Walker variant

We describe an infant with a deletion of 8q21→22 who had distinct clinical manifestations including minor facial anomalies, a congenital heart defect, a Dandy-Walker variant, and mild to moderate developmental delay. Her facial characteristics included small, wide-spaced eyes, asymmetric bilateral epicanthal folds, a broad nasal bridge, a “carp-shaped” mouth, micrognathia, and prominent, apparently low-set ears. Three other reports describe children with larger proximal deletions of 8q that include 8q21 and q22. These four children all have similar facial appearance. Of the others reported, one had a congenital heart defect and one had craniosynostosis. This case, in addition to the previously noted three cases, helps in delineating a recognizable syndrome. © 1995 Wiley-Liss, Inc.