Implications of prenatal diagnosis of the fetus with both interstitial deletion and a small marker ring originating from chromosome 5

We describe a patient with 47,XY,del(5)(p11p13), +mar observed in prenatal screening. We performed analyses including G-banding, multi-color fluorescent in situ hybridization (mFISH) for fetal chromosome detection. After birth array-based comparative genomic hybridization (aCGH), bacterial artificial chromosome (BAC)-FISH was carried out to define the chromosomal changes precisely. The mFISH revealed that a ring chromosome that had originated from chromosome 5. The aCGH showed that this fetus had a terminal duplication, an interstitial deletion, and a pericentromeric duplication of the short arm of chromosome 5. This complex alteration resulted in partial trisomy 5p15.33-p15.31, partial monosomy 5p14.3-p13.2, and partial trisomy 5p12-p11. To clarify these alterations, we performed BAC-FISH using BAC clones related to deleted and duplicated regions, and found that a derivative (der) chromosome 5 showed the presence of hybridization signals from the duplicated region at 5p15.33 and the loss of hybridization signals from the deleted region at 5p14.2. In addition, FISH analysis confirmed the origin of the marker chromosome. Hybridization signals from the second intervening sequence at 5p13.1, between the deleted region and the pericentric duplicated region, were present on the marker ring chromosome.

Searching for genes for cleft lip and/or palate based on breakpoint analysis of a balanced translocation t(9;17)(q32;q12)

OBJECTIVE

Identification of the breakpoints of disease-associated chromosome rearrangements can provide informative clues to a positional cloning approach for genes responsible for inherited diseases. Recently, we found a three-generation Japanese family segregating balanced chromosome translocation t(9;17)(q32;q12). One of the subjects had cleft lip and palate. We examined whether regions near the breakpoint could be associated with cleft lip and/or palate.

METHODS

We determined the breakpoints involved in the translocation by fluorescence in situ hybridization analysis and subsequent long-range polymerase chain reaction. In order to study the role of these disrupted regions in nonsyndromic cleft lip and/or palate, we performed mutation analysis and a haplotype-based transmission disequilibrium test using tagging single-nucleotide polymorphisms in the flanking regions of the breakpoints in white and Filipino nonsyndromic cleft lip and/or palate populations.

RESULTS

Sequence analysis demonstrated that two genes, SLC31A1 (solute carrier family 31 member 1) on chromosome 9 and CCL2 (chemokine ligand 2) on chromosome 17, were rearranged with the breaks occurring within their introns. It is interesting that SLC31A1 lies closed to BSPRY (B-box and SPRY domain), which is a candidate for involvement with cleft lip and/or palate. Some of the variants in BSPRY and CCL2 showed significant p values in the cleft lip and/or palate population compared with the control population. There was also statistically significant evidence of transmission distortion for haplotypes on both chromosomes 9 and 17.

CONCLUSIONS

The data support previous reports that genes on chromosomal regions of 9q and 17q play an important role in facial development.

Exposure to bisphenol A is associated with recurrent miscarriage

BACKGROUND

Little is known about the influence of high exposure to bisphenol A on recurrent miscarriage and immunoendocrine abnormalities.

METHODS

Serum bisphenol A, antiphospholipid antibodies (aPLs), antinuclear antibodies (ANAs), natural killer cell (NK) activity, prolactin, progesterone, thyroid-stimulating hormone (TSH) and free T4 were examined in 45 patients with a history of three or more (3-11) consecutive first-trimester miscarriages and 32 healthy women with no history of live birth and infertility. Subsequent pregnancy outcome and embryonic karyotype of abortuses were examined prospectively.

RESULTS

The mean+/-SD values for bisphenol A in patients were 2.59+/-5.23 ng/ml, significantly higher than the 0.77+/-0.38 ng/ml found for control women (P=0.024). High exposure to bisphenol A was associated with the presence of ANAs but not hypothyroidism, hyperprolactinaemia, luteal phase defects, NK cell activity or aPLs. A high level of bisphenol A in itself did not predict subsequent miscarriage.

CONCLUSION

Exposure to bisphenol A is associated with recurrent miscarriage.

Parental origin and cell stage of non-disjunction of double trisomy in spontaneous abortion

Using polymorphic analysis of microsatellites, we investigated the parental origin and mechanism of double trisomies seen in cases of spontaneous abortion. We obtained chorionic villi from spontaneous abortions, and peripheral blood from females who experienced abortion and their spouses. Chromosomal analysis of 170 cases revealed four cases with double trisomy. The karyotypes of these cases are 48,XX,+16,+22, 48,XXY,+18, 48,XX,+15,+21 and 48,XX,+2,+5. In the present study, the incidence of double trisomy was 2.4% of spontaneous abortions. Polymorphic analysis of microsatellites indicated that extra chromosomes were all of maternal origin in the four cases of double trisomy. The predominance of maternal origin in cases of double trisomy is similar to cases of single trisomy. The result also indicated that both extra chromosomes in two cases occurred by non-disjunction at the first meiotic division, and extra chromosomes in the other two cases occurred by non-disjunction at the first mitotic division. The mean maternal age in cases of double trisomy was significantly higher than that in cases of single trisomy. These findings suggest the possibility that abnormal separation of two or more chromosomes may occur simultaneously in oogonia, and that this phenomenon may increase in relation to the increase in age of women.

[Clinical symptoms of the Rett syndrome patients with MECP2 gene abnormalities]

Mutations in a gene on the X-chromosome encoding methyl-CpG-binding protein 2 (MECP2) cause Rett syndrome. We examined clinical symptoms of 27 patients with Rett syndrome (aged 2 to 37 years), diagnosed by the criteria of the Rett Syndrome Diagnostic Criteria Work Group. having MECP2 gene mutations. Two novel MECP2 mutations, 119 del AG resulting in amino acid frame-shift 40fs43X and C to G transversion resulting in amino acid change of F157L, were found. All patients had the most important symptoms of this syndrome, including loss of acquired purposeful hand skills followed by stereotyped hand movements. Two patients had mild perinatal abnormalities. Nine showed psychomotor delay or hypotonia before 6 months. Five patients over 4 years old did not have microcephaly. Speech was preserved in five patients. According to the criteria, 18 cases were diagnosed as Rett syndrome variants. Sixteen out of 26 patients over 3 years old were able to walk (61.5%), and 22 had epilepsy (84.6%). Mutations of the 5 patients without microcephaly were R133C, P225R, R255X, R306C and 376fs386X, whereas those of the 5 variants with preserved speech were 34fs123X, R133C, R255X and R270. Common T158M mutation was detected in 4 patients, R255X in 7 and R270X in 4. Patients with the same mutations showed different phenotypes. Patients with R133C and R306C presented a mild phenotype without microcephaly. Of the proposed diagnostic criteria, the following three may not be essential: apparently normal prenatal and perinatal period, apparently normal psychomotor development through the first 6 months, and deceleration of head growth between 5 months and 4 years.

PCBs, Hexachlorobenzene and DDE are not Associated with Recurrent Miscarriage

PROBLEM

A case-control study was designed to evaluate any associations between high exposure to polychlorinated biphenyls (PCB), hexachlorobenzene (HCB) and the 1,1,1,-trichloro-2,2-bis (p-chlorophenyl) ethane (DDT) metabolite 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (DDE) and recurrent miscarriage and immunoendocrine abnormalities.

METHODS OF STUDY

A total of 18 kinds of co-planer PCBs, HCB, DDE, natural killer cell (NK) activity, antiphospholipid antibodies, antinuclear antibody, prolactin, progesterone, thyroid-stimulating hormone (TSH) and free T4 were examined in 45 patients with a history of three or more (3-11) consecutive first-trimester miscarriages and 30 healthy women with no history of live birth and infertility.

RESULTS

There were no differences in mean +/- S.D. values in serum samples for PCBs, HCB and DDE between patients and controls. Hypothyroidism, hyperprolactinemia, luteal phase defects, NK cell activity and the presence of autoantibodies were also not associated with levels of any of the compounds in the patients.

CONCLUSION

PCBs, HCB and DDE are not associated with miscarriage and immunoendocrine abnormalities in patients with a history of recurrent miscarriage.

Transmission of chromosomal abnormalities: participation of chromosomally unbalanced gametes in fertilization and early development of unbalanced embryos in the Chinese hamster

Using 14 Chinese hamster stocks with various reciprocal translocations, chromosomally unbalanced gametes were produced and used to investigate the participation of the unbalanced gametes in fertilization and the development of unbalanced embryos. The selection of chromosomally abnormal gametes during fertilization was investigated by the chromosomal analysis of meiotic cells in heterozygotes for the 14 reciprocal translocations and pronuclei of fertilized ova obtained from crossing these heterozygotes. Compared with the expected frequencies from meiotic metaphase II (MII) scoring, the frequencies of male pronuclei having commonly a deficiency of chromosome 1 (q14-->q42) or chromosome 3 (p23-->q31) in one-cell embryos decreased significantly. However, the frequencies of male pronuclei with other abnormalities were all consistent with those expected from MII scoring. In contrast, the frequencies of female pronuclei with any karyotype including the same ones, as those decreased in male pronuclei from the translocation heterozygotes were all consistent with those estimated from MII scoring. These results suggest that gametes with nullisomies as well as disomies for any chromosomal segments may mostly participate in fertilization, whereas some sperm nullisomic for the specific segments of chromosomes 1 and 3 may fail to fertilize. On the other hand, the zygotic selection of chromosomal imbalance was investigated by direct analyses of pre-implantation embryos from crosses between chromosomally normal females and male heterozygotes from the 14 stocks with various reciprocal translocations. The chromosomal and morphological analysis revealed that some embryos were arrested in development at the two-cell stage and their common abnormality was partial monosomy for chromosome 1 or 2. Embryos with partial monosomy including chromosomes 1, 3 and 4 showed arrested development at four-eight-cell stages. Among day 4 embryos, some chromosomally unbalanced embryos, mainly with a deficiency of other segments, such as chromosomes 1p, 2q, 5q and 8, had fewer blastomeres than karyotypically normal and balanced embryos. The homology between the mouse and the Chinese hamster chromosomes relating to the developmental abnormalities at early stages was partially confirmed.

Nonsense and frameshift mutations in ZFHX1B, encoding Smad-interacting protein 1, cause a complex developmental disorder with a great variety of clinical features

Mutations in ZFHX1B, encoding Smad-interacting protein 1 (SIP1), have been recently reported to cause a form of Hirschsprung disease (HSCR). Patients with ZFHX1B deficiency typically show mental retardation, delayed motor development, epilepsy, microcephaly, distinct facial features, and/or congenital heart disease, in addition to the cardinal form of HSCR. To investigate the breadth of clinical variation, we studied DNA samples from six patients with clinical profiles quite similar to those described elsewhere for ZFHX1B deficiency, except that they did not have HSCR. The results showed the previously reported R695X mutation to be present in three cases, with three novel mutations-a 2-bp insertion (760insCA resulting in 254fs262X), a single-base deletion (270delG resulting in 91fs107X), and a 2-bp deletion (2178delTT resulting in 727fs754X)-newly identified in the other three. All mutations occurred in one allele and were de novo events. These results demonstrate that ZFHX1B deficiency is an autosomal dominant complex developmental disorder and that individuals with functional null mutations present with mental retardation, delayed motor development, epilepsy, and a wide spectrum of clinically heterogeneous features suggestive of neurocristopathies at the cephalic, cardiac, and vagal levels.

Molecular analysis of Japanese patients with Rett syndrome: Identification of five novel mutations and genotype-phenotype correlation

Rett syndrome is an X-linked dominant neurodevelopmental disorder that affects females almost exclusively. The recent identification of mutations of the methyl-CpG-binding protein 2 gene (MECP2) in patients with RTT, encouraged us to analyze the gene in 37 Japanese patients divided into classical RTT (14 cases), variant RTT (13 cases), and mentally retarded patients with Rett-like features (10 cases). Mutations in MECP2 were identified from most of the patients with classical and variant RTT (25 of 27 cases). Six reported common mutations were detected in 17 cases, and rare single nucleotide substitutions were found in 3 patients. In addition, one insertion mutation (1189insA) and four deletion mutations including one double deletion mutant (451delG, 100del4, 1124del53 and 881del289 plus 1187del8) were newly identified. In the 10 mentally retarded patients with Rett-like features, however, no mutation was detected in the coding region of MECP2. The finding of MECP2 mutations in 92.5% of patients with RTT indicates that RTT fulfilling the diagnostic criteria are due to genetic alteration.

Ectopic expression of MAFB gene in human myeloma cells carrying (14;20)(q32;q11) chromosomal translocations

Chromosome 14q +, which represents a chromosomal rearrangement involving the immunoglobulin heavy chain gene (IgH) locus, is a genetic hallmark of human multiple myeloma (MM). Here, we report the identification of (14;20)(q32;q11) chromosomal translocations found in MM cells. Double color fluorescence in situ hybridization analyses pinpointed the breakpoints at the 20q11 locus in two MM cell lines within a length of at most 680 kb between the KIAA0823 and MAFB gene loci. Among the transcribed sequences in the vicinity of the breakpoints, an ectopic expression of the MAFB gene, which is located at 450 - 680 kb telomeric to one of the breakpoints and encodes a member of the MAF family basic region / leucine zipper transcription factor, was demonstrated to be associated with t(14;20). This finding, together with that of a previous study describing its transforming activity, suggests that the MAFB gene may be one of the targets deregulated by regulatory elements of the IgH gene as a result of t(14;20).

Cytogenetic study of a new Ph1-positive cell line (NALM-1)

The chromosomes of a cell line (NALM-1) derived from the leukocytes of a patient with chronic myelocytic leukemia (CML) were examined with several banding techniques. The modal chromosome number was 46 and the cells contained a Philadelphia chromosome (Ph1), due to the standard translocation of the missing segment of the long arm of chromosome No. 22 onto the distal end of the long arm of chromosome No. 9, i.e., t(9;22) (q34;q11). The Ph1-positive modal cells of the NALM-1 line also had two common marker chromosomes, an extra X-chromosome, and missing chromosomes in groups No. 7, 9, and 15. Immunologic examination of the NALM-1 cells revealed them to have non-T-non-B (null) surface characteristics. An antigen specific for cells of acute leukemia and a human la-like antigen were detected. These facts suggested that the NALM-1 cell line originated from CML cells and maintained the cytogenetic and Immunologic characteristics of such cells.

Chromosomes and causation of human cancer and leukemia: XXVIII. Value of detailed chromosome studies on large numbers of cells in CML

Comparison of the chromosome findings obtained on routine examination (10-50 cells) of the marrows from patients with Ph1-positive CML with those based on a large number (110-500 cells) of metaphases in six of these patients, in whom appropriate material was available, revealed the presence of small percentages of aneuploid cells in the marrow during the chronic phase of the disease and not seen with the routine procedure. These aneuploid cells may ultimately constitute the dominant clone during the blastic phase of the chronic myelocytic leukemia (CML). Furthermore, karyotypically abnormal cells, in addition those observed on routine study, were detected in the blastic phase when a large number of cells was examined. The value and implications of these observations are discussed.