Inherited pericentric inversion of chromosome no. 2 with Robertsonian translocation (13q 14q) resulting in trisomy for chromosome 13q

This report includes a patient with an inherited pericentric inversion of chromosome No. 2 in addition to a Robertsonian translocation resulting in trisomy for chromosome 13q. The chromosomal constitution of the proband was 46,XX,inv(2) (pter leads to p11 : : q14 leads to p11 : : q14 leads to qter); t(13,14) (13qter leads to 13p11 : : 14q11 leads to 14qter). Sequential QFQ, RFA and GTG banding techniques were employed on the chromosomes of all family members. The chromosomal constitutions of the father and his first child were normal while the mother had an inversion of chromosome No. 2 [46,XX,inv(2) (pter leads to p11 : : q14 leads to p11 : : q14 leads to qter)]. The proband inherited this abnormal chromosome. In addition, she had a de novo Robertsonian translocation involving chromosomes 13q and 14q resulting in trisomy of chromosome 13q.     

De novo 9-break-event in one chromosome 21 combined with a microdeletion in 21q22.11 in a mentally retarded boy with short stature

We report on a moderately mentally retarded 12-year-old boy of short stature showing the most complex chromosomal rearrangement (CCR) within a single chromosome ever described. A de novo derivative chromosome 21 was recognized in GTG-banding shortly after birth. However, the nature of the rearrangement remained obscure up to the application of the chromosome 21-specific centromere-near multicolor-FISH (subcenM-FISH) probe set and of six selected locus-specific probes along chromosome 21. An unbalanced 9-break-event was uncovered with breakpoints in 21p13, 21p13-->12, 21q11.2, 21q21.1, 21q22.11, 21q22.11, 21q22.12, 21q22.22 and 21q22.3. A deletion of 21q22.11 was detected by application of the BAC probe bk249H10. The karyotype can be described as 46,XY,der(21)(:p13-->p1213::q22.3-->q22.22:: q11.2-->p1213::q11.2-->q21.1::q22.11-->q21.1::q22.12--> q22.22::p13-->p13). The clinical signs can either be due to gene inactivation in connection with structural changes at the break and fusion regions, to the building of new fusion genes within the CCR and/or to the deletion of genes in 21q22.11.     

Evidence for Three Novel QTLs for Adiposity on Chromosome 2 With Epistatic Interactions: The NHLBI Family Heart Study

We sought to identify quantitative trait loci (QTLs) by genome‐wide linkage analysis for BMI and waist circumference (WC) exploring various strategies to address heterogeneity including covariate adjustments and complex models based on epistatic components of variance. Because cholesterol‐lowering drugs and diabetes medications may affect adiposity and risk of coronary heart disease, we excluded subjects medicated for hypercholesterolemia and hyperglycemia. The evidence of linkage increased on 2p25 (BMI: lod = 1.59 vs. 2.43, WC: lod = 1.32 vs. 2.26). Because environmental and/or genetic components could mask the effect of a specific locus, we investigated further whether a QTL could influence adiposity independently of lipid pathway and dietary habits. Strong evidence of linkage on 2p25 (BMI: lod = 4.31; WC: lod = 4.23) was found using Willet's dietary factors and lipid profile together with age and sex in adjustment. It suggests that lipid profile and dietary habits are confounding factors for detecting a 2p25 QTL for adiposity. Because evidence of linkage has been previously detected for BMI on 7q34 and 13q14 in National Heart, Lung, and Blood Institute Family Heart Study (NHLBI FHS), and for diabetes on 15q13, we investigated epistasis between chromosome 2 and these loci. Significant epistatic interactions were found between QTLs 2p25 and 7q34, 2q37 and 7q34, 2q31 and 13q14, and 2q31–q36 and 15q13. These results suggest multiple pathways and factors involving genetic and environmental effects influencing adiposity. By taking some of these known factors into account, we clarified our linkage evidence of a QTL on 2p25 influencing BMI and WC. The 2p25, 2q24–q31, and 2q36–q37 showed evidence of epistatic interaction with 7q34, 13q14, and 15q13.     

Phenotypical characterization of 13q deletion syndrome: Report of two cases

Patients with 13q deletion syndrome are characterized with different phenotypical features depending on the size and location of the deleted region on chromosome 13. These patients fall into three groups: In Group 1, deleted region is in the proximal and does not extend into q32; in Group 2, deleted region involves proximal to the q32 and in Group 3 q33-q34 is deleted. We present two cases with 13q syndrome with two different deleted region and different severity on clinical features: One case with interstitial deletion belongs to the Group 1 with mild mental retardation and minor malformations and the other case with terminal deletion belongs to Group 3 with moderate to severe mental retardation and major malformations.     

Allelotype of human thyroid tumors: loss of chromosome 11q13 sequences in follicular neoplasms.

Two classes of genes are the targets of mutations involved in human tumorigenesis: oncogenes, the activation of which leads to growth stimulation, and tumor suppressor genes, which become tumorigenic through loss of function, often through allelic deletion. To obtain evidence for a role for tumor suppressor genes in thyroid tumorigenesis, we examined DNA from 80 thyroid neoplasms for loss of heterozygosity in multiple chromosomal loci using 19 polymorphic genomic probes. None of the informative thyroid tumors studied had allelic loss detected with probes for chromosome 2q (D2S44), 3p (D3F15S2, D3S32), 3q (D3S46), 4p (D4S125), 6p (D6S40), 8q (D8S39), 9q (D9S7), 12p (D12S14), 13q (D13S52), 17p (D17S30), or 18q (D18S10). One of eight of the follicular adenomas had a 10q deletion detected with marker D10S15, and one of 26 had a 10q deletion detected with D10S25. One of two of the follicular carcinomas had an 11p deletion in the H-ras locus. The most significant findings were on chromosome 11q13, the site containing the putative gene predisposing to multiple endocrine neoplasia type I. Four of 27 follicular adenomas had loss of heterozygosity for probes in this region. Allelic deletions were detected with the following probes: D11S149, PYGM, D11S146, and INT2. None of 13 informative papillary carcinomas and none of two follicular carcinomas had loss of heterozygosity detectable with these 11q13 markers. Allelic loss is a relatively infrequent event in human thyroid tumors. Deletions of chromosome 11q13 are present in about 14% of follicular, but not papillary, neoplasms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characterization of a partial trisomy 16q with FISH. Report of a patient and review of the literature.

Characterization of a partial trisomy 16 q with FISH: Report of a patient and literature review: We report on a 28-year-old male patient with severe growth and mental retardation, severe behavioural problems, especially automutilation, and a spastic quadriplegia. He showed no specific dysmorphism. The karyotype was 46, XY, dir dup(16) (q11.2-q13). The clinical and cytogenetical findings are compared with 3 previously reported cases with proximal duplication 16q.     

Familial whole-arm translocations (1;19), (9;13), and (12;21): a review of 101 constitutional exchanges

We report here on 3 familial whole-arm translocations (WATs), namely the 8th instance of t(1;19)(p10;q10) and 2 novel exchanges: t(9;13)(p10;q10) and t(12;21)(p10;q10). The exchanges (1;19) and (12;21) were ascertained through a balanced carrier, whereas the t(9;13) was first diagnosed in a boy with a trisomy 9p syndrome and der(9p13p). Results of FISH analyses with the appropriate α-satellite probes were as follows. Family 1, t(1;19): the D1Z5 probe gave a strong signal on both the normal chromosome 1 and the der(1q19p) as well as a weak signal on the der(1p19q). Family 2, t(9;13): the centromere-9 alphoid and D13Z1/D21Z1 probes under standard stringency gave no signal on the der(9p13p) in both the proband and a carrier brother, whereas the der(9q13q) was labelled only with the centromere-9 alphoid repeat in the latter; yet, this probe under low stringency revealed a residual amount of alphoid DNA on the der(9p13p) in the carrier. Family 3, t(12;21): the D12Z3 probe gave a signal on the normal chromosome 12 and the der(12p21q), whereas the D13Z1/D21Z1 repeat labelled the der(12q21p), the normal chromosome 21, and both chromosomes 13. Out of 101 WATs compiled here, 73 are distinct exchanges, including 32 instances between chromosomes with common alphoid repeats. Moreover, 7/9 of recurrent WATs involved chromosomes from the same alphoid family. Thus constitutional WATs appear to recur more frequently than other reciprocal exchanges, often involve chromosomes with common alphoid repeats, and can mostly be accounted for the great homology in alphoid DNA that favours mispairing and illegitimate nonhomologous recombination.     

Translocation +(7p+; Bq-) associated with recurrent abortion.

A balanced translocation was found in a normal female with a history of four abortions. On the basis of the Giemsa-banding pattern the abnormality was interpreted as to be a translocation of a part of the long arm of chromosome 13 to the short arm of chromosome some 7:t(7;13)(7qter leads to 7p22::13q14 leads to 13qter;13q14 leads to 13pter::7p22 leads to 7 pter). Problems in genetic counseling are discussed with respect to this case.     

Direct duplication 16q11.1----16q13 is not associated with a typical dysmorphic syndrome

In this report we present a 3-year-old girl with partial trisomy of the long arm of chromosome 16 due to a direct duplication 16q11.1----q13 (karyotype: 46, XX, dir dup(16) (pter----cen----q11.1----q13::q11.1----q13::q13----qter]. She presented moderate mental retardation and severe hyperkinetic behaviour. Slight dysmorphic stigmata but no internal anomalies were found.     

Physical localisation of the chromosomal marker D13S31 places the Wilson disease locus at the junction of bands q14.3 and q21.1 of chromosome 13

D13S31 is the marker closest to the Wilson disease locus according to genetic analysis. Its physical localisation was refined by fluorescent in situ hybridisation to the junction to chromosomal bands 13q14.3 and 13q21.1. Using polymerase chain reaction analysis, D13S31 and D13S59 (the closest proximal and distal marker, respectively) were found to be located on the end of the der(13) consisting of 13pter-13q14.3: in the somatic cell hybrid ICD, and to be absent from the cell lines WC-H38B3B6 containing a del(13) (13pter-q13::13q21.1-qter) and KSF39 containing a del(13) (13pter-q14.1:).     

Comparative genomic hybridization reveals a partial de novo trisomy 6q23-qter in an infant with congenital malformations: delineation of the phenotype

We report the use of comparative genomic hybridization (CGH) to define the origin of a small extra segment (unidentifiable by classical cytogenetics) present in a de novo add(13)q34 chromosome that we found in the karyotype of a newly born boy with congenital heart defects, brain anomalies and dysmorphic signs. Initial investigation with fluorescence in situ hybridization (FISH) and a chromosome-13-specific library revealed that the excess material was not derived from chromosome 13. To uncover the origin of the unknown chromosome material, CGH was carried out on DNA isolated from blood lymphocytes of the patient. By using a conventional fluorescence microscope with no digital imaging devices, a single distinct region with gain of fluorescent intensity was observed on distal chromosome 6q. Confirmation of this finding by FISH with a chromosome-6-specific paint and a subtelomeric yeast artificial chromosome clone from 6q26-q27, in combination with the band morphology of the small extra chromosomal segment, allowed us to diagnose the additional material as being derived from chromosome 6q23-qter. FISH with a telomere 13q probe detected a terminal deletion of 13q34-qter on the derivative chromosome 13, indicating that the der(13) was a result of a translocation event. Genotyping of the hypervariable apolipoprotein (a) gene, which lies within 6q26-q27, showed that the additional chromosome 6 material was inherited from the mother. The karyotype of the proposita is therefore: 46,XY,-13,+der(13)t(6;13)(q23;q34) de novo (mat). Our results confirm the usefulness of CGH as an attractive alternative method for the characterization of constitutional small genetic imbalances and contribute to the delineation of the trisomy 6q23-qter phenotype. Received: 26 November 1996 / Revised: 2 January 1997     

Pericentric inversions of chromosome number 9: benign or harmful?

Pericentric inversions of chromosome number 9 have been studied in 4 different probands: a normal female with designation 46,XX,inv(9)(p12q13); a male with Down syndrome designated as 47,XY,+21,inv(9))p13q13); a premature infant with multiple, congenital malformations who was 46,XX,inv(9)(p12q21), and a Down syndrome proband with 47,XYqs,+21,inv(9)(p13q21). All 4 cases were shown to be inherited based on family studies. These families are discussed with reference to the literature as to what possible effect this structural change could have on the reproductive capability of a normal carrier and what guidelines are available for counseling such a carrier.     

Two reciprocal translocations t(9p+;13q−) and t(13q−;21q+)

Summary Two reciprocal balanced translocations 46,XY,t(9;13)(p23;q21) and 46,XX,t(13;21)(q21;q21), identified by RFA- and GTG-banding, are presented along with a complete study of both families.In the second case a 3:1 segregation is associated with an unbalanced 2:2 segregation, as demonstrated in the two surviving sons: one with interchange trisomy 21 and the other with partial trisomy 13 and partial monosomy 21. This suggests that the presence of this translocation, and possibly of other translocations involving morphologically similar chromosomes, could signify a high risk of having chromosomal disorders in offspring.     

Homozygosity for a Robertsonian translocation (13q14q) in three offspring of heterozygous parents

A family containing three homozygous carriers for a Robertsonian (13q14q) translocation, 44,XX or XY,t(13q14q),t(13q14q), is reported. Their parents are first cousins, and both are heterozygous carriers of the same (13q14q) translocation. The fertility of both the heterozygous and homozygous carriers is discussed.     

Pericentric inversions in man: personal experience and review of the literature

Summary The Leuven cytogenetic centre experience on pericentric inversion in man is discussed with exclusion of the pericentric inversions of the heterochromatic blocks of chromosomes 1 and 9. In a total of 51,500 patients, referred for constitutional chromosome analysis during the period 1970–1985, pericentric inversions were found in 24 index patients. The breakpoints detected in these different pericentric inversions are summarized and compared to those found in previous reports. Bands 2p13, 2q21, 5q31, 6c21, 10q22, and 12q13 were shown to be repeatedly involved in the different studies and, furthermore, breakpoints at bands 2q11, 5p13, 5p15, 5q13, 7q11, 11q25, and 14p11 were present in this study as well as in our previous review on reciprocal autosomal translocations. In 13 familial pericentric inversions, even after exclusion of all inversion carrier probands, a 1.6:1 excess of pericentric inversion carriers versus karyotypically normal progeny was observed. While chromosomally unbalanced offspring represent 3.5% of all chromosomally investigated liveborns of the present study, 7.1% of all liveborn inversion carrier offspring presented with a mental retardation and/or multiple congenital anomalies (MR/MCA) problem. Additional chromosomal abnormalities, i.e. a 21 trisomy and an accessory small ring chromosome were observed in two pericentric inversion carriers. These data and results are discussed and compared to the data available in the literature.     

Maternal origin of extra marker chromosome 1Q31.1-qter and 13pter-q12.12 in a child with dysmorhic features

Maternal origin of extra marker chromosome Iq31.l-qter and 13pter-q12.12 in a child with dysmorphic features: We describe a twenty-days-old female child with dysmorphic features and chromosomal analysis with GTG-banding revealed an extra marker chromosome. Fluorescence in situ hybridization (FISH) study of extra marker chromosome confirmed to be maternal der(13) chromosome, contained 1q31.1-qter and 13pter-q11 chromosomal material and resulted from a maternal balanced translocation t(1;13)(q31.1; q12.12). The child had the majority of trisomy 1q clinical features: dysmorphic features, micropthalmia, high arched palate, long philthrum, micrognathia, hypertelorism, low set ears, short sternum, overlapping fingers, valgus of wrists, right knee and ankle joints were in flexion contractures. This is the first case of trisomy 1q with an extra marker chromosome which also contained chromosome 13pter-q12.12 material.     

Retinoblastoma in a boy with a de novo mutation of a 13/18 translocation: The assumption that the retinoblastoma locus is at 13q141, particularly at the distal portion of it

Summary In serial cytogenetic examinations of peripheral lymphocytes from retinoblastoma patients, we found a patient with sporadic bilateral retinoblastoma with a de novo mutation of a 13/18 translocation, with their respective breakpoints at 13q141 and 18q122. The simultaneous de novo occurrence of retinoblastoma and the chromosomal rearrangement involving 13q14 in the proband suggests that the gene locus for retinoblastoma is at 13q141, particularly at the distal portion of it. Deletion mapping data are compatible with this suggestion.     

Thirteenfold increase of chromosomal aberrations non-randomly distributed in chagasic children treated with nifurtimox

Chromosomal aberrations were analyzed from cultures of peripheral lymphocytes in 2 groups of chagasic children, before and after treatment with nifurtimox. The mean incidence of chromosomal aberrations increased from control values of 1.75 +/- 1.39 (8 patients) to 23.55 +/- 9.55 (6 patients) at a significance of P less than 0.0001. G-banding analysis of chromosomal aberration sites revealed that treated patients present coincidence in the chromosome regions affected: 1p11, 1q11-12, 9q11-13, 17q11-21, 2p21, 2q23, 2q31, 2q33, 6p21, 6p21, 7q32, 13q14, 13q22, 15q22. These data indicate a non-random distribution of chromosomal aberrations induced by nifurtimox therapeutic treatment.     

Molecular cytogenetic analysis of eight inversion duplications of human chromosome 13q that each contain a neocentromere

Neocentromeres are fully functional centromeres that have arisen in previously noncentromeric chromosomal locations on rearranged chromosomes. The formation of neocentromeres results in the mitotic stability of chromosomal fragments that do not contain endogenous centromeres and that would normally be lost. Here we describe a unique collection of eight independent patient-derived cell lines, each of which contains a neocentromere on a supernumerary inversion duplication of a portion of human chromosome 13q. Findings in these patients reveal insight into the clinical manifestations associated with polysomy for portions of chromosome 13q. The results of FISH and immunofluorescent analysis of the neocentromeres in these chromosomes confirm the lack of alpha-satellite DNA and the presence of CENtromere proteins (CENP)-C, -E, and hMAD2. The positions of the inversion breakpoints in these chromosomes have been placed onto the physical map of chromosome 13, by means of FISH mapping with cosmid probes. These cell lines define, within chromosome 13q, at least three distinct locations where neocentromeres have formed, with five independent neocentromeres in band 13q32, two in band 13q21, and one in band 13q31. The results of examination of the set of 40 neocentromere-containing chromosomes that have thus far been described, including the 8 neocentromere-containing chromosomes from chromosome 13q that are described in the present study, suggest that chromosome 13q has an increased propensity for neocentromere formation, relative to some other human chromosomes. These neocentromeres will provide the means for testing hypotheses about sequence requirements for human centromere formation.     

Molecular cytogenetic identification and characterization of a de novo supernumerary neocentromeric derivative chromosome 13

We report a young girl with microphthalmia, conductive deafness, aortic isthmus stenosis, laryngomalacia, and laryngeal stenosis carrying a de novo supernumerary neocentromeric derivative chromosome 13. For the precise identification and characterization of the eu- and heterochromatic content of the marker chromosome, straightforward molecular cytogenetic analyses were performed, such as chromosome microdissection, FISH with different probes (e.g. wcp, alphoid centromeric probes, BAC), centromere-specific multicolor FISH (cenM-FISH), and multicolor banding (MCB). The analyses demonstrated that the marker consisted of an inverted duplication (partial tetrasomy) of the distal portion of chromosome 13 that was separated from the endogenous chromosome 13 centromere. Using an all-centromere probe and multicolor cenM-FISH, no alpha-satellite DNA hybridization signal was detectable on any portion of the derivative chromosome. The presence of a functional and active neocentromere on the derivative chromosome 13 was confirmed by positive immunofluorescence signals with CENP-C antibodies. BAC-FISH confirmed the cytogenetic localization of the neocentromere in band 13q31.3. Thus the patient had a mosaic conventional karyotype mos 47,XX,+inv dup(13)(qter-->q21.3::q21.3-->q31.3-->neo-->q31.3-->qter)[6]/46,XX [49].