Complex karyotypic changes, including rearrangements of 12q13 and 14q24, in two leiomyosarcomas

Cytogenetic investigation of short-term cultures from two leiomyosarcomas revealed complex karyotypic changes in both cases. The first tumor, a subcutaneous leiomyosarcoma of the knee, had the karyotype 70-80,XY, +X, +Y, +1, +1, +2, +2, +3, +3, +4, +4, +7, +7, +8, +8, +9, +10, +15, +15, +16, +16, +18, +19, +20, +21, +21, +22, +22,t(?;5)(5;21)(?;q35p11;q11), t(?;5)(5;21)(?;q35p11;q11), +del(11)(q22),der(13)t(12;13)(q13;q22),der(14)t(9;14)(p11;p11), +14p+, +t(20;?)(q13;?), +t(20;?)(q13;?), +2 mar. A polyploidized clone with 120-150 chromosomes was also observed. DNA flow cytometry revealed only one abnormal peak, corresponding to a DNA index of 1.76. The other tumor, a uterine leiomyosarcoma, had the karyotype 61-67, X, -X, +1, +3, +5, +6, +7, +8, +9, +12, +13, +15, +t(1;1)(p32;q32), +der(1)t(1;8)(p13;q11), +del(2)(p11), +del(2)(q22), +del(2)(q22), +del(3)(p13), +i(5p),t(8;14)(q24;q24), +der(8)t(8;14) (q24;q24), +del(10)(p12),der(11)t(11;15)(p15;q11),t(16;?)(p13;?),t(16;?)(q24;?), der dic(17) (17pter----cen----17q25::hsr::17q25----cen----17pte r), +t(19;?)(p13;?), +der dic(20)(20pter----cen----20q12::hsr::20q12----cen----+ ++20pter), +mar. The DNA index was 1.59. The finding in these leiomyosarcomas of rearrangements of the same regions of chromosomes 12 and 14 that are involved in the tumor-specific t(12;14)(q14-15;q23-24) of uterine leiomyoma indicates that the same genes in 12q and 14q might be important in the pathogenesis of benign and malignant smooth muscle tumors.     

Molecular cytogenetic characterization of non-Hodgkin lymphoma cell lines.

Spectral karyotyping (SKY) and comparative genomic hybridization (CGH) have greatly enhanced the resolution of cytogenetic analysis, enabling the identification of novel regions of rearrangement and amplification in tumor cells. Here we report the analysis of 10 malignant non-Hodgkin lymphoma (NHL) cell lines derived at the Ontario Cancer Institute (OCI), Toronto, designated as OCI-Ly1, OCI-Ly2, OCI-Ly3, OCI-LY4, OCI-Ly7, OCI-Ly8, OCI-Ly12, OCI-Ly13.2, OCI-Ly17, and OCI-Ly18, by G-banding, SKY, and CGH, and we present their comprehensive cytogenetic profiles. In contrast to the 52 breakpoints identified by G-banding, SKY identified 87 breakpoints, which clustered at 1q21, 7p15, 8p11, 13q21, 13q32, 14q32, 17q11, and 18q21. G-banding identified 10 translocations, including the previously described recurring translocations, t(8;14)(q24;q32) and t(14;18)(q32;q21). In contrast, SKY identified 60 translocations, including five that were recurring, t(8;14)(q24;q32), t(14;18)(q32;q21), t(4;7)(p12;q22), t(11;18)(q22;q21), and t(3;18)(q21;p11). SKY also identified the source of all the marker chromosomes. In addition, 10 chromosomes that were classified as normal by G-banding were found by SKY to be rearranged. CGH identified seven sites of high-level DNA amplification, 1q31-32, 2p12-16, 8q24, 11q23-25, 13q21-22, 13q32-34, and 18q21-23; of these, 1q31-32, 11q23-25, 13q21-22, and 13q32-34 have previously not been described as amplified in NHL. This comprehensive cytogenetic characterization of 10 NHL cell lines identified novel sites of rearrangement and amplification; it also enhances their value in experimental studies aimed at gene discovery and gene function.     

Cytogenetic analysis of 363 consecutively ascertained diffuse large B-cell lymphomas.

Cytogenetic analysis was performed on 363 biopsy specimens with histologically confirmed diffuse large B-cell lymphoma (DLBCL), consecutively ascertained at the Memorial Sloan-Kettering Cancer Center, New York, between 1984 and 1994. Among 248 samples successfully karyotyped, clonal chromosomal abnormalities were noted in 215 (87%). The salient cytogenetic features of DLBCL from this analysis comprised the following. Breakpoints clustered, in decreasing frequency, at 10 recurring sites: 14q32, 18q21, 1q21, 3q27, 1p36, 8q24, 3p21, 6q21, 1p22, and 22q11. Of these, deletion breaks affecting bands 3p2 and 1p22 and translocation breaks affecting bands 14q32, 3q27, and 1q2 were frequent and distinctive for this subset of lymphomas. Translocations affecting band 14q32 were noted in 110 cases (51%) of which 42 (20%) had t(14;18)(q32;q21), 21 (10%) had t(8;14)(q24;q32) or t(8;22)(q24;q11), 14 (6.5%) had t(3;14)(q27;q32) or t(3;22)(q27;q11), and 33 (15%) had other rearrangements of 14q32. Among 144 new translocations detected in the entire group, the breakpoints in 19 were recurrent and clustered at three sites: 1q21, 3q27, and 14q32. Regions of common cytogenetic deletions were identified at 11 sites, 1p36, 1p33-34, 1p31, 1q32, 3p25-26, 3p21, 3q21, 6q15, 6q21, 6q23-24, and 7q32, suggesting possible loss of candidate tumor suppressor genes associated with DLBCL development. Of these, only those at 6q21, 6q23, and 7q32 have previously been described in lymphoid neoplasms. The group of DLBCL with translocations affecting band 14q32 showed a significantly different pattern of additional cytogenetic changes compared to the group lacking such translocation. This new comprehensive cytogenetic characterization provides the basis for investigations aimed at identifying molecular mechanisms as well as the clinical impact of cytogenetic changes in DLBCL.     

Multiple apparently unrelated clonal chromosome abnormalities in a squamous cell carcinoma of the tongue

We have cytogenetically examined short-term cultures from a squamous cell carcinoma of the tongue, a tumor type in which chromosome aberrations hitherto have not been reported. No less than 12 pseudodiploid clones were detected, giving the tumor karyotype 46,X,der(X)t(X;1)(q26;p32),der(1)(Xqter→Xq26::1p32→cen→1q42:),del(13)(q11q21),t(15;?) (q26;?)/46,XX,t(1;?)(p34;?),inv(2)(p21q11)/46,XX,t(1;10)(p32;q24)/46,XX,+der(1)(12pter→ 12p11::1p11→cen→1q32::11q13→11q32→1q42:),del(11)(q13q22), - 12, der(17)t(1:17) (q42;p13)/46,XX,inv(1)(p22q44)/47,XX,del(1)(q32),der(17)t(1:17)(p22;q25),der(1)inv(1) (q25q44)t(1;17)(p22;q25),ins(14;7)(q11;q22q36), + 14/46,XX,t(1;4)(q23;q35)/46,XX,t(1;21) (q25;q22),t(2;10)(q31;q26),t(22;?)(q12;?)/46,XX,del(1)(q32)/46,XX,t(1;8)(q44;q21)/46,XX, t(2;21)(q11;p11)/46,XX,t(9;11)(q34;q13). The large number of apparently unrelated abnormalities leads us to suggest that the carcinoma may have been of multiclonal origin.     

11q23 abnormalities in children with acute nonlymphocytic leukemia (M4-M5). Association with previous chemotherapy

Cytogenetic studies of 12 patients aged less than 14 years with acute nonlymphoblastic leukemia (ANLL) (M4-M5) showed structural abnormalities on chromosome 11 at band q23-q24 in five cases (41.8%). Four of these 12 patients had ANLL (M4-M5) after treatment with cytostatics for non-Hodgkin lymphoma in one case and for an acute lymphoblastic leukemia (ALL) in the other three. Three of these four cases had 11q23 abnormalities [one [one 46,XY,t(11;17)(q23;25); another 47,XY,+8,-15,del(11)(q23),+der(15)t(15;?)(p11;?); the third 47,XX,+8,t(3;17) (p11;q25),t(4;11)(q21;q23)] and one had a normal karyotype on being diagnosed ANLL (M4-M5). The notable increase of ANLL (M4-M5) in our patients who had received cytostatics as treatment for a previous neoplasia makes evaluation of our results timely in comparison with those of other groups who use these therapeutic protocols.     

Chromosome abnormalities in hairy cell leukaemia variant

We describe chromosome abnormalities in 6 patients with hairy cell leukaemia (HCL) variant, a rare B-cell disorder with clinical and laboratory features intermediate between HCL and B-prolymphocytic leukaemia (B-PLL). All but one had marked splenomegaly and a raised white blood cell count (median 40 × 10⁹/l) with over 80% nucleolated hairy cells. These cells had a B-cell immunophenotype distinct from that of typical HCL. All patients but one are alive with stable disease with a median follow-up of 60 months. Numerical chromosome changes included loss of chromosomes 2, 3, 4, 6, 10, 19, 21, and X. Three cases had translocations involving the immunoglobulin gene regions: t(14;17)(q32;q11), t(14;22)(q32;q11), and t(2;8)(p11.12;q24). Immunocytochemistry demonstrated the presence of the MYC protein in cells from the case with t(2;8) but not in two others. Other structural abnormalities included t(3;10)(q27;q22) and t(3;12)(q27;q13) in the same patient, der(17)t(7;10;17) (p11;q27;q22), t(1;3)(q25;p21), t(8;21)(p12;q11), t(17;21)(p11;p11), del(6)(q15), del(7)(q34), and del(14)(q24). Genes Chromosom Cancer 10:197–202 (1994). © 1994 Wiley-Liss, Inc.     

Cytogenetic study of non-Hodgkin lymphoma from South India. histologic and geographic correlations

Cytogenetic analysis of fine needle aspiration cultures was performed on 189 patients with non-Hodgkin lymphoma from South India. Successful karyotyping was possible in 97 patients (51.3%). Burkitt lymphoma constituted 56% of the cases studied followed by diffuse type 20%, follicular 8.8%, lymphoblastic 6.6%, and unclassified 6.6%. Characteristic chromosomal translocations were t(8;14)(q24;q32) [32.2%], t(8;22)(q24;q11) [10%], t(2;8)(p12;q24) [2.2%], t(14;18)(q34;q21) [3.3%], and t(11;14)(q23;q32) [2.2%]. Notable geographical variation of some structural abnormalities was the finding in the present study such as, lower frequency of t(14;18) in follicular lymphomas and higher frequency of t(8;14) in Burkitt lymphomas when compared with the Western studies.     

Detection of translocations involving the HOX11/TCL3-locus in 10q24 by interphase fluorescence in situ hybridization

The t(10;14)(q24;q11) and its variant t(7;10)(q35;q24), which are recurrent in acute T-cell leukemia, lead to activation of the HOX11/TCL3-gene in chromosomal region 10q24 by juxtaposing this gene to one of the T-cell receptor loci. In the present study, we established a diagnostic assay for detecting these translocations by interphase fluorescence in situ hybridization (FISH). BAC clones flanking the HOX11/TCL3-locus were obtained from a fingerprinted BAC-contig of chromosomal region 10q24. BAC clones located proximal and distal of the HOX11/TCL3-locus were differently labeled and applied to interphase-FISH in seven normal controls and eight T-cell neoplasms with t(10;14)(q24;q11) or t(7;10)(q35;q24). In over 1600 nuclei of controls, a considerable split defined as separation of each one signal for the proximal and distal probe by more than three times the signal diameter was observed in only one cell. In contrast, all T-cell neoplasms with t(10;14) or t(7;10) contained at least 47% of nuclei with a signal split indicating a breakpoint in the HOX11/TCL3-locus. Thus, the established double-color FISH approach provides a new reliable and routinely applicable tool for diagnosing breakpoints in the HOX11/TCL3-locus.     

Quantitative acute leukemia cytogenetics.

Using literature data on cytogenetic abnormalities in 3,612 cases of acute myeloid leukemia (AML) and 1,551-cases of acute lymphocytic leukemia (ALL), we have attempted to quantify the information value of finding the typical ALL- and AML-associated chromosome aberrations. Sensitivity, specificity, and predictive value of finding or not finding a given aberration were calculated for several diagnostic scenarios: for the differential diagnosis between ALL and AML when the patient is known to have acute leukemia, for the differential diagnosis among AML FAB subtypes in a patient with known AML, and for the differential diagnosis between ALL FAB subtypes in a patient with known ALL. The specificities were generally high, close to 1. The highest sensitivities in AML were found for +8, t(15;17)(q22;q11), t(8;21)(q22;q22), and -7 (all greater than 0.1), and in ALL for t(9;22)(q34;q11), t(4;11)(q21;q23), and +21 (again all greater than 0.1). In the AML subtypes, the highest sensitivities were 0.89 for t(15;17)(q22;q11) in M3, followed by 0.40 for t(8;21)(q22;q22) in M2, 0.30 for inv(16)(p13q22)/del(16)(q22)/t(16;16)(p13;q22) in M4, and 0.16 for t(9;11)(p21;q23) in M5. In the ALL subtypes, the highest sensitivities were 0.71 and 0.11 for t(8;14)(q24;q32) and t(8;22)(q24;q11), respectively, in L3, 0.23 for t(9;22)(q34;q11) in L2, and 0.18 and 0.13 for +21 and t(4;11)(q21;q23), respectively, in L1. The highest (1.0) positive predictive values in the AML versus ALL comparison were found for t(1;3)(p36;q21), inv(3)(q21q26), t(6;9)(p23;q34), t(7;11)(p15;p15), t(8;16)(p11;p13), t(8;21)(q22;q22), t(15;17)(q22;q11), and, as sole anomalies, for +4, +9, and +11. In the reverse comparison, ALL versus AML, positive predictive values of 1.0 were found for t(1;14)(p32-34;q11), dup(I)(q12-21q31-32), t(2;8)(p12;q24), t(8;14)(q24;q32), t/dic(9;12)(p11-12;p11-13), t(10;14)(q24;q11), and t(11;14)(p13;q11). Among the AML subgroups, the highest predictive values were: 1.0 for M3 if t(15;17), 0.91 for M2 if t(8;21), 0.86 for M4 if inv/del(16)/t(16;16), and 0.82 for M5 if t(9;11). Among the ALL subtypes, positive predictive values of greater than 0.8 were reached only for the L3-associated aberrations t(2;8) (1.0), t(8;14) (0.95), t(8;22) (0.87), and dup(I) (0.80). The highest negative predictive values were in AML 0.98 that the disease is not M3 if t(15;17) is not found, and in ALL 0.96 that the patient does not have L3 if a t(8;14) is not detected.     

Mantle cell lymphoma with 8q24 chromosomal abnormalities: a report of 5 cases with blastoid features.

The t(11;14)(q13;q32) resulting in cyclin D1 overexpression is consistently present in mantle cell lymphoma. However secondary chromosomal aberrations are also extremely common. Of these, 8q24 abnormalities associated with the t(11;14) are rare. Over the course of 10 years at M.D. Anderson Cancer Center, we identified five cases of mantle cell lymphoma in which conventional cytogenetic analysis revealed complex karyotypes, including the t(11;14) and 8q24 abnormalities: one with t(8;14)(q24;q32), one with t(2;8)(q13;q24), and three with add(8)(q24). We performed fluorescence in situ hybridization (FISH) studies on all cases. In the case with the t(8;14), IgH/myc fusion signals were identified, and in the case with the t(2;8), split c-myc signals were detected. In the three cases with add(8)(q24), one case had split c-myc signals and two cases had three copies of c-myc. Thus, the c-myc gene was involved in all cases. All five neoplasms had blastoid morphologic features, and four cases, including the cases with the t(8;14) and t(2;8), had leukemic involvement. We conclude that 8q24 abnormalities involving the c-myc gene are uncommon secondary abnormalities that occur in a subset of mantle cell lymphomas. C-myc gene abnormalities are associated with blastoid cytologic features and also may be associated with leukemic involvement.     

Frequency of structural abnormalities of the long arm of chromosome 12 in myelofibrosis with myeloid metaplasia

Among cytogenetic studies of 205 patients diagnosed as myelofibrosis with myeloid metaplasia, we found seven cases with structural abnormalities of the long arm of chromosome 12. The karyotype showed six balanced translocations, that is, t(4;12)(q33;q21), t(5;12)(p14;q21), t(1;12)(q22;q24), t(12;17)(q24;q11), t(7;12) (p11;q24), and t(1;12)(p12;q24), as well as other cytogenetic abnormalities such as del(12)(q21;q24) and inv(12) (p12q24). Some isolated cases involving the 12q21 region have also been described in the literature. Importance of rearrangement of chromosome 12 in 12q21 or 12q24 is underlined by the authors suggesting a proto-oncogene accountable mechanism of leukemogenesis.     

Chromosomal anomaly of 6q in chronic myelogenous leukemia (CML)

Anomalies of chromosome 6q, along with other chromosomal anomalies, are described in the bone marrow cells of two patients with chronic myelogenous leukemia (CML). One patient, a 14-year-old male, developed the karyotype 46,XY,t(1;6)(p36;q15),del(3)(q25),del(17)(p11),? inv(17)(q12q24) during blastic crisis of his disease. The other patient, a 24-year-old male, had the karyotype 46,XY,del(6)(q13),t(9;22)(q34;q11) during the early phase of his disease and evolution of i(17q) in the karyotype late in the disease.     

Chromosome abnormalities in 16 Finnish patients with Burkitt's lymphoma or L3 acute lymphocytic leukemia

Eleven patients with Burkitt's lymphoma (BL), i.e., small noncleaved non-Hodgkin's lymphoma, and 5 patients with Burkitt-type acute lymphocytic leukemia (ALL-L3) were selected for chromosome study. Two of the 16 patients had no B-cell markers, but the erythrocyte marker--glycophorin A--was present on the surface of the leukemic blasts. The critical breakpoint at 8q24 was detected in 14 of the 16 patients, whereas this aberration was not detected in any of the 134 patients belonging to other subgroups of non-Hodgkin's lymphoma or ALL that we studied during the same period. In addition to the t(8;14)(q24;q32), the following translocations with the breakpoint at 8q24 were seen: t(2;8)(p11;q24), t(8;11)(q24;q13) in BL, and t(2;8;14)(p11 or p12;q24;q32) in ALL. Additional aberrations seen more than once were trisomy #7 and abnormalities in chromosomes #1, #11, and #13.     

Characterization of chromosomal breakpoints in an ALL patient using cross-species color banding

Cross-species color-banded karyotype (Rx-FISH) results were compared with those of conventional G-banded metaphases from the same sample. Breakpoints and karyotype were confirmed as 46,XX,t(8;22)(q24;q11), der(9)t(1;9)(q21;p13) through the novel technology of cross-species color banding in an acute leukemic patient (ALL, L3); the karyotype was 46,XX,t(8;22)(q24;q11),der(9)t(1;9)(q25;p24) by conventional G-banding.     

Molecular characterization of the t(10;14) translocation breakpoints in T-cell acute lymphoblastic leukemia: further evidence for illegitimate physiological recombination

The t(10;14)(q24;q11) translocation is a non-random chromosome change seen in the leukemic cells of 5-10% of patients with T-cell acute lymphoblastic leukemia (T-ALL). Recent studies support the hypothesis that the translocation occurs in the course of aberrant physiological recombination and results in the juxtaposition of a T-cell receptor (TCR) gene in 14q11 with a putative oncogene, TCL3, in 10q24. We cloned and sequenced the translocation breakpoints on both derivative 10q+ and 14q- chromosomes from a patient with t(10;14)(q24;q11) T-ALL. Two distinct diversity segments of TCRD, D delta 2 and D delta 3, were identified at the two translocation breakpoints on chromosome 14. The 9.5 kb DNA that separates these two subunits in the germline was deleted, possibly in the course of a D-D joining event. The two chromosome 10 breakpoints were 10 nucleotides apart and occurred in the immediate vicinity of a pseudo-heptamer signal motif. N-region addition is also evident at the breakpoint on the derivative chromosome 10. Our observations strongly suggest that the IG/TCR recombinase normally involved in V-(D)-J joining was involved in the process of the t(10;14)(q24;q11) translocation.     

Translocation between chromosomes 8q24 and 14q11 in T-cell acute lymphoblastic leukemia

Cytogenetic study was performed on a patient with T-cell acute lymphoblastic leukemia (T-ALL). It revealed a chromosomal translocation between chromosome bands 8q24 and 14q11. 8q24 is known to encode the oncogene c-myc, while 14q11 encodes the genes for T-cell receptor-alpha (TCR-alpha) and T-cell receptor-delta (TCR-delta). Therefore, this chromosomal translocation t(8;14) (q24;q11) seemed to be unique and specific to T-cell malignancy.     

A specific translocation,t(12;14)(q14–15; q23–24), characterizes a subgroup of uterine leiomyomas

We have cytogenetically investigated short-term cultures initiated from 34 uterine leiomyomas, all of which were histologically completely benign. Clonal chromosome abnormalities were detected in five cases, a normal female complement in 22, whereas, in the remaining seven tumors no karyotype could be established. Apparently identical reciprocal translocations, t(12;14)(q14–15;q23–24), were found as the sole abnormality in four tumors. The fifth abnormal case contained a t(2;14)(p11;p11). We conclude that chromosome aberrations may be found in myomas of the uterus, and that t(12;14)(q14–15;q23–24) characterizes a subset of these tumors.     

The (11;14)(q13;q32) translocation in multiple myeloma. A morphologic and immunohistochemical study

We identified 24 cases of multiple myeloma with the t(11;14)(q13;q32). In 22 cases, the t(11;14)(q13;q32) was part of a complex karyotype, and in 2 cases it was an isolated abnormality. All patients had clinical and laboratory features consistent with multiple myeloma. The median degree of plasma cell involvement in the bone marrow was 60%, and in 10 cases, the plasma cells had a lymphoplasmacytoid appearance. Of the 24 cases, 21 had intermediate or high proliferative rates based on labeling index studies. Immunohistochemical studies performed on all bone marrow biopsy specimens showed strong cyclin D1 nuclear positivity in 19 cases. There also was strong cyclin D1 nuclear positivity found in 6 of 30 additional cases without the t(11;14)(q13;q32) demonstrated by routine cytogenetics. The t(11;14)(q13;q32) in multiple myeloma results in overexpression of the cyclin D1 protein, which can be demonstrated by immunohistochemical stain. The cyclin D1 stain results in the additional cases of multiple myeloma suggest that the t(11;14)(q13;q32) may be more common than previously thought and may be missed by routine cytogenetics, particularly if the proliferative rate is low.     

Multiple unrelated clonal chromosome abnormalities in an in situ squamous cell carcinoma of the skin

We have cytogenetically analyzed short-term cultures from an in situ squamous cell carcinoma of the skin (Bowen's disease). The following mosaic tumor karyotype was found: 46,XX, -1, +der(1)(pter----p22::q11----cen----p22:), -9, +der(9)t(1;9)(q11; p24)/46,XX,t(3;6) (q21;p21)/46,XX,t(5;14)(q13;q24),t(7;18)(q32;q11)/46,XX,t(8;11)(p22;q13) /46, XX,t(8;11) (p22;q13),t(15;17) (q13;q24)/46,XX,t(12;15)(q12;p11). None of the rearrangements correspond to previously known cancer-associated abnormalities. Two of the clones are obviously related, and it is reasonable to assume that the t(15;17) developed as an evolutionary change in a cell that already contained t(8;11)(p22;q13). Since five clones without cytogenetic similarities were found in this in situ skin carcinoma, we suggest that the tumor was of polyclonal origin. It is impossible to decide whether all, or indeed any, of the visible abnormalities constitute pathogenetically essential primary changes, or merely represent chromosomal markers of secondary importance in tumorigenesis.     

Recessive cancer genes in meningiomas? An analysis of 31 cases

Cytogenetic studies on 31 human meningiomas revealed clonal abnormalities in 14 of them. Monosomy 22 was present in three cases as the only abnormality, and in five it was associated with monosomy 18, monosomy 14, loss of X, loss of Y, and trisomy 20, respectively. We found a number of rearrangements involving chromosome #22: an i psu dic(22)(pter----q11::q11----pter) in two cases and a t(18;22)(q12;q11) in another case. Two cases showed a complex translocation involving #7 and #14: t(2;7;14)(q23;q36;q22) and t(1;7;14)(q25;q32;q22), respectively. Other clonal chromosome abnormalities were del(1p) (present in two cases); der(9)t(9;?)(q34;?); der(7)t(7;?)(q31;?); der(22)t(22;?)(q11;?); and a 9p+ chromosome. The relevance for the pathogenesis of human meningiomas of these chromosome anomalies is also discussed with reference to the previous literature. The possible involvement of recessive cancer genes present on the long arm of chromosome #22 is also discussed.