Partial trisomy 4 resulting from a complex maternal rearrangement of chromosomes 2, 4, and 18 with interstitial translocation

Summary A woman presented a complex chromosome rearrangement with translocation between chromosome 2 and 4 in addition to an insertion of the band 4q12q13 in the long arm of chromosome 18. The authors present a case study of the daughter who displayed the abnormal chromosome 18 and trisomy of band 4q12q13.     

Transposition of 9q34 and 22 (q11→qter) regions has a specific role in chronic myelocytic leukemia

Summary Six cases are reported of variant Ph translocations found among 240 patients with Ph-positive CML. Five cases had a three-chromosome rearrangement involving, in addition to chromosomes 9 and 22, chromosomes 7, 4, 2(two), and 3 respectively, and one case had a two-chromosome rearrangement 22/5. A review of the literature revealed that three- and two-chromosome variant Ph translocations are observed with equal frequency. It is postulated that all variant translocations are indeed three-chromosome rearrangements, that the specific event for the formation of the Ph chromosome is the reciprocal translocation 9/22, and that the transposition of regions 9q34 and 22 (q11qter), plays a major role in the development of CML.     

Clinical and cytogenetic studies of the Prader-Willi syndrome: Evidence of phenotype-karyotype correlation

Summary Twenty-seven patients with the presumed diagnosis of Prader-Willi syndrome (PWS) were studied clinically and cytogenetically. The patients were classified into three study groups on the basis of their clinical pictures: group 1 with 12 children meeting the strict diagnostic criteria for PWS; group 2 with nine floppy infants and young children, aged 3 years or less, without obesity and hyperphagia; and group 3 with six older children in whom some characteristic features of the syndrome were absent. High-resolution GTG banding of prometaphase chromosomes revealed del(15)(q11.1;q12) in eleven and t(15;15)(qterp11.2::q12qter) in one of the twelve group 1 patients. In group 2, four patients had del(15)(q11.1;q12), one had t(15;15)(qterp11.1::q13qter), and the remaining four had normal karyotypes. The deleted segment common to the 17 patients with the chromosome aberrations was confined to subband 15q11.2. On the other hand, all six group 3 patients had normal karyotypes. These findings indicated that when strictly defined PWS is absolutely correlated with chromosome 15 aberrations, i.e, there is a positive phenotype-karyotype correlation, and that the aberrations are etiologically related to the syndrome. Parental origin of the deleted chromosome was determined in seven patients, with OFQ-heteromorphisms being used as hereditary markers. The deleted chromosome originated from the paternal chromosome 15 in six patients and from the maternal 15 in one.     

Confirmation of regional assignment of nucleoside phosphorylase (NP) on chromosome 14 by gene dosage studies

Summary Gene dosage studies yielded results consistent with assignment of the locus for nucleoside phosphorylase to band 14q13. The red blood cells from a patient with the karyotype 47,XX,+der(14),t(8;14)(8qter8q24: :14q2114pter)pat had enzyme activity 50% higher than red cells from 47 normal controls, two trisomies involving chromosomes other than 14, and five balanced translocations involving chromosome 14. On the other hand, the red cells of a case with a karyotype 45,XX,-14,-22,+der(22),t(14;22)(14qter14q11 or 14q12::22p1122qter)mat and a case with a karyotype 47,XX, +der(14),t(14;16)(14pter14q11::16q2416qter)mat had normal activity.     

A deletion in chromosome 22 can cause digeorge syndrome

Summary An association between DiGeorge's syndrome and an unbalanced chromosomal rearrangement leading to trisomy 20pter20q11 and monosomy 22pter22q11 was found in four individuals belonging to one family. These and other data from the literature are interpreted to suggest that DiGeorge's syndrome can be caused by deletion of a gene located in chromosome 22, probably in band 22q11.     

Regional mapping of catalase and Wilms tumor—aniridia,genitourinary abnormalities,and mental retardation triad loci to the chromosome segment 11p1305→p1306

Summary Gene dosage effects for catalase (CAT) were studied in two unrelated patients with an interstitial deletion involving 11p13 to determine precisely the sites of the genes for CAT and the Wilms tumor—aniridia, genitourinary abnormalities, and mental retardation triad (WAGR) in the 11p13 band. Case 1 had the aniridia-Wilms tumor association, and case 2 showed the AGR triad. The karyotypes identified by high resolution banding techniques were 46,XY,del(11)(pterp13::p11.11qter) for case 1 and 46,XY,t(2;17) (q23;q25), del(11) (pterp13::p11.2 qter) for case 2. In both cases, the distal breakpoints of the deleted chromosomes 11 appeared to have occurred on the middle portion of 11p13 (11p1305p1306). The level of erythrocyte CAT activities in case 1 was reduced (47% of normal), while that in case 2 was normal. The results suggested not only that both the CAT and WAGR should be mapped to chromosome region 11p1305p1306, but also that in this region the CAT locus is more distally placed than the WAGR locus. Because of the proximity of the two gene loci, assays of erythrocyte CAT may be useful to identify a submicroscopic deletion in some patients with sporadic aniridia and to predict a risk of developing Wilms tumor.     

Further regional localization of the genes for human acid alpha glucosidase (GAA), peptidase D (PEPD), and alpha mannosidase B (MANB) by somatic cell hybridization

Summary We have further regionally localized the gene for human acid alpha glucosidase (GAA) to 17q21q23 by examinaiton of hybrid clones derived from a fusion between human fibroblasts carrying a 17/19 balanced translocation (17pter17q23::19p13.319pter; 19qterp13.3::17q2317qter) and a mouse line deficient in thymidine kinase. These hybrids were constantly maintained in HAT selective media in order to select for the presence of the human thymidine kinase gene on the intact chromosome 17 (17q21-q22) or the 17/19 (17pter17q23::19p13.319pter) translocation chromosome. We detected human GAA by rocket immunoelectrophoresis, using a human specific heterologous antibody raised against human acid alpha glucosidase (GAA) (Honig et al. 1984). Three secondary clones, which contained the 17/19 translocation and no intact chromosome 17 or 19, were still positive for GAA. Two of these secondary clones contained the distal portion of the 17/19 translocation chromosome, with a break in the band 17q21 (probably at 17q21.2), attached to a mouse chromosome. Combined with earlier results (Weil et al. 1979; Nickel et al. 1982; Honig et al. 1984), the gene for GAA can be assigned to 17q21.217q23. Additionally, these clones were negative for human peptidase D (PEPD), alpha mannosidase B (MANB), and phosphohexose isomerase (PHI). Combined with previous results (Ingram et al. 1977; Bruns et al. 1979), these results exclude the genes for PEPD and MANB from 19pter19p13.3 and confirm the exclusion of the gene for PHI from this segment of chromosome 19 (Wilson et al. 1984; Ingram et al. 1977).     

Adjacent 2 meiotic disjunction. Report of a case resulting from a familial 13q;15q balanced reciprocal translocation and review of the literature

Summary An abnormal short-lived female infant with almost complete trisomy 13 (pterq32 or 33) and partial monosomy 15 (pterq14 or 15) resulting from an adjacent 2 meiotic disjunction of a paternal reciprocal translocation is described. Cases with monosomy of chromosome 15 material are reviewed. It appears likely that monosomy of an interstitial long arm segment, approximating to 15q2124, imparts the lethality associated with the full monosomic condition. Adjacent 2 disjunction in man has been further characterised by reviewing the literature.     

SOD-A and chromosome 21

Summary A balanced maternal chromosome translocation (9p24;21q214) resulted in two offspring with unbalanced karyotypes. One of these, a girl trisomic for both segment 9pter9p24 and segment 21pter21q214, was found to have a SOD-A activity not significantly different from those found in a group of five cases with trisomy 21. However, clinical evaluation of this girl revealed no symptoms of the Down syndrome. These findings suggest that, providing the gene dosage theory is correct, the gene for SOD-A is probably localized on chromosome 21 proximal to, or in, band q21.     

Interstitial deletion of the short arm of chromosome 3

Summary A de novo interstitial deletion of the short arm of chromosome 3 was prenatally diagnosed in a male fetus, karyotype 46,XY,del(3)(pterp14.2::p11qter). The fetus had craniofacial dysmorphisms, a single transverse palmar crease, ulnar deviation in the wrists, cardiovascular anomalies, a slight ureteric dilatation and a mobile caecum. Our observations are compared with five other cases with interstitial deletion of the short arm of chromosome 3 to delineate further the proximal 3p deletion syndrome. The gene for beta-galactosidase-1 (GLB-1) has previously been assigned to chromosome 3(p21q21). The absence of a gene dosis effect for GLB-1 in this study indicates exclusion of GLB-1 from 3(p11p14.2).     

10q(q23→qter) duplication: GOTs,HK1, and other gene markers

Summary Gene marker analyses have been carried out in a patient with 10q(q23qter) duplication. The observed elevation of red cell glutamic oxaloacetic transaminase activity is compatible with earlier somatic cell hybridization studies that mapped the locus to this region. Hexokinase-1 activity in the red cells was normal, which is consistent with its prior assignment to the unaffected part of chromosome 10 (10pterq23).     

Structural study of fucoidan from Cladosiphon okamuranus tokida

A structural study was carried out on a fucoidan isolated from the brown seaweed Cladosiphon okamuranus. The polysaccharide contained fucose, glucuronic acid and sulfate in a molar ratio of about 6.1 : 1.0 : 2.9. The results of Smith degradation showed that this polysaccharide has a linear backbone of 13-linked -fucopyranose with a half sulfate substitution at the 4-positions, and a portion of the fucose residues was O-acetylated. The data obtained from partial acid hydrolysis, a methylation analysis and NMR spectra indicated that the -glucuronic acid residue is linked to the 2-positions of the fucose residues, which were not substituted by a sulfate group. These results indicated that the average structure of this fucoidan is as follows: -[(3Fuc-4(±OSO₃-)1–)₅3[GlcA12]Fuc1–]_n–. (Half of each fucose residue was sulfated. One O-acetyl ester was present in every 6 fucose residues.)     

Partial trisomy of 11 and 22 due to familial translocation t(11;22) (q23;q11), inherited in three generations

Summary A 1-year-old girl with partial trisomy of 11 (q23qter) and 22 (pterq11) is presented. She had severe mental retardation, cleft palate, congenital heart disease, congenital dislocation of the hip, and other anomalies.The extra acrocentric chromosome was identified as der(22),t(11;22) (q23;q11) from a familial translocation and by G-and R-banding methods. The mother and the maternal grandfather were carriers of balanced rcp(11;22) (q23;q11) translocations.The possible relations between phenotypic features and the karyotypes of partial trisomy 11 and 22 are discussed.     

Full trisomy 7 and Potter syndrome

Summary A patient with typical Potter's syndrome and full trisomy 7 is described. All previous reports on chromosome 7 abnormalities, whether monosomic or trisomic, p or q, are reviewed and discussed, establishing two 7q trisomy snydromes: 7q227q31 and 7q22, q317qter. Some implications of the finding of full trisomy 7 in a case of Potter's syndrome are discussed.     

A deletion panel of the long arm of the X chromosome: subregional localization of 22 DNA probes

Summary Two males and two females with different but overlapping deletions on the proximal long arm of the X chromosomes have been investigated. Their karyotypes, which have been well characterized by high resolution banding techniques, are 46,Y,del(X)(pterq21.1:: q21.33qter); 46,Y,del(X) (pterq21.2::q21.31qter); 46,X,del(X) (pterq21.31::q24.3qter) and 46,X,del (X)(pterq21.1:). A deletion panel, which makes it possible to subdivide the long arm of the X chromosome into seven subregions, has been established using the genomic DNA from the four families, and applied to the fine subregional localization of the loci for 22 DNA probes. Based on the results obtained, the possible location of the loci in question has been narrowed down considerably, in some cases to an area of only 5% of the previously assigned region; hybridization to Southern blots of a panel with well-characterized chromosome deletions is thus a powerful means of localizing DNA probes, especially with respect to the X probes.Part of the results from this investigation were published at Human Gene Mapping 9 as abstracts     

Cytogenetic and molecular analysis of a de novo tandem duplication of chromosome 21

Summary We have characterised by cytogenetic and molecular analysis a de novo tandem duplication of chromosome 21. High resolution chromosome examination of lymphocytes revealed the following karyotype in 90% of the cells: 46,XY,dir dup (21)(pterq22.300::q11.205 qter). Of these cells, 10% showed a normal karyotype. Gene dosage of chromosome 21 sequences by a slot blot method indicated that the duplication extends from D21S16 to D21S55. In situ hybridization with probes close to the borders of the duplicated segment confirmed the gene dosage data and gave results consistent with a true tandem duplication of chromosome 21. Pulsed field gel electrophoresis of the patient's DNA showed an abnormal restriction band common to D21S55 and D21S16, confirming that the junction point between the two homologous parts of the tandem chromosome brings these two sequences into proximity. Restriction fragment length polymorphism analysis indicated that the abnormal chromosome was maternal in origin and that the rearrangement of chromosome 21 could not have occurred at a post-zygotic stage of development but resulted from a recombination event during maternal gametogenesis. The possible mechanisms of formation of the abnormal chromosome are discussed, as is the presence of cells with normal chromosomes 21, in the patient.     

Localization of the LDHA gene to 11p14→11p15 by in situ hybridization of an LDHA cDNA probe to two translocations with breakpoints in 11p13

Summary Lymphoblastoid cell lines established from two individuals with apparently balanced translocations involving 11p13 were used for LDHA regional localization. The karyotypes were 46,XY,t(4;11)(q21;p13) and 46,XY,t(1;11) (p22;p13). In situ hybridization of a human LDHA cDNA probe to chromosome preparations from these cell lines resulted in specific labeling over bands p14p15 of the normal chromosomes 11 and over bands 11p1411p15 of the derivative chromosomes 4 and 1. These results exclude LDHA from any region proximal to 11p13 and localize the gene to 11p1411p15.     

Probable assignment of soluble isocitrate dehydrogenase (IDH1) to 2q33.3

Summary Gene dosage effects for soluble isocitrate dehydrogenase (IDH₁) were investigated in four unrelated cases with abnormalities involving the long arm of chromosome 2. Case 1 was trisomic for 2q33.3qter, Case 2 monosomic for 2q33.3q35, Case 3 trisomic for 2q11.2q24.2, and Case 4 monosomic for 2q23q24.2. These abnormalities were de novo except in Case 1, where trisomy 2q resulted from a maternal translocation. The red cell IDH₁ levels were significantly reduced in Cases 1 (41.4% of normal value) and 2 (51.9%), while they were normal in Cases 3 and 4. The low IDH₁ level also in the father of Case 1 (43.6%), together with the common electrophoretic phenotype of IDH₁ in red cells as well as leukocytes, led us to suppose that Case 1 was really heterozygous for common and probable null alleles, and that the IDH₁ gene locus could be excluded from 2q33.3qter. On the other hand, normal IDH₁ values in the parents of Case 2 were consistent with the hemizygosity for this locus in Case 2. The results suggested that the IDH₁ locus could be assigned to the 2q33.3 band, especially the proximal portion of it.     

The gene coding for the α-chain of human propionyl-CoA carboxylase maps to chromosome band 13q32

Summary The human gene encoding the -polypeptide of propionyl-CoA carboxylase (PCC) has hitherto been localized to the distal half of the long arm of chromosome 13, segment 13q22q34. We studied the enzyme activities of mitochondrial carboxylases in cell cultures obtained from patients with different deletions of chromosome 13. By setting the PCC activity in normal diploid cell cultures (control group) at 100%, cell cultures with trisomy 13 showed 150% activity. In contrast, one of four patients with partial monosomy 13 had an enzyme activity of only 50%. Thus, by comparative deletion mapping, combined with studies of the gene-dosage effect, we have been able to assign the PCCA gene locus to chromosome band 13q32.     

Assignment of human phosphoribosylglycinamide synthetase locus to region 21q221

Summary The enzymatic activity of phosphoribosylglycinamide synthetase (GARS) has been studied in several cases of partial monosomies and full and partial trisomies 21. An excess of GARS activity was found in regular trisomy 21 with a trisomy 21/normal ratio equal to 1.55. A 0.99 ratio was found in 21q2121pter monosomy; a 0.54 ratio was found in 21qter21q22 monosomy; a 0.88 ratio, in 21q2121pter trisomy, and a 1.46 ratio, in 21q22.1 trisomy. Consequently, the GARS gene locus, assigned to chromosome 21, could be localized in subband 21q22.1.