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Myelodysplasia and leukemia syndrome with monosomy 7: a genetic perspective.

Acquired monosomy 7 is a frequent finding in myelodysplastic syndromes, including acute myelogenous leukemia. A subset of these patients has been described with an apparently distinct condition: myelodysplasia and leukemia syndrome with monosomy 7 (MLSM7). We report 2 brothers, 3 and 5 years of age, with MLSM7 and review other reports of familial occurrence. Genetic factors appear to be important in the cause of MLSM7, but the reported families do not fit neatly into any monogenic pattern. Recognition of the frequently familial nature of this condition requires hematological evaluation and genetic counseling for the families of patients with MLSM7.

Adolescent↗

Partial monosomy of chromosome 1p36.3: characterization of the critical region and delineation of a syndrome.

We describe 5 patients ranging in age from 3 to 47 years, with karyotypic abnormalities resulting in monosomy for portion of 1p36.3, microcephaly, mental retardation, prominent forehead, deep-set eyes, depressed nasal bridge, flat midface, relative prognathism, and abnormal ears. Four patients have small hands and feet. All exhibited self-abusive behavior. Additional findings in some of the patients include brain anomalies, optic atrophy, hearing loss and skeletal deformities. The breakpoints within chromosome 1 were designated at 1p36.33 (1 case). Thus, the smallest region of deletion overlap is 1p36.33-->1pter. Detection of the abnormal 1 relied on high resolution G-band analysis. Fluorescence in situ hybridization (FISH) utilizing a DNA probe (Oncor D1Z2) containing the repetitive sequences in distal 1p36, confirmed a deletion of one 1 homologue in all 5 cases. The abnormal 1 resulted from a de novo deletion in only one patient. The remaining patients were either confirmed (3 cases) or suspected (1 case) to have unbalanced translocations. Despite the additional genetic imbalance present in these four cases, monosomy of 1p36.33 appears to be responsible for a specific clinical phenotype. Characterization of this phenotype should assist in the clinical diagnosis of this chromosome abnormality.

Abnormalities, Multiple↗

Trisomy 3q25.1-qter and monosomy 8p23.1-pter in a patient: cytogenetic and molecular analysis with delineation of the phenotype.

We describe a 4-year-old boy with partial 3q trisomy and distal 8p monosomy. The patient presented with mental retardation, dysmorphic face, congenital heart defect, brain and genital anomalies, and behavioral problems. The conventional cytogenetic analysis showed a 46,XY,add(8p) karyotype. Reverse painting and microsatellite analysis demonstrated a partial monosomy of 8p23.1 --> pter and a partial trisomy of 3q25.1 --> qter. The data suggest that the chromosomal rearrangement originated from a de novo translocation in a paternal germinal cell. The phenotype observed in our patient resulted from the combination of those defects described in the isolated dup(3q) and distal del(8p) syndromes.

Child, Preschool↗

X-chromosome monosomy in the myelin-deficient rat mutant.

We have identified three examples of female Wistar rats exhibiting the tremor and seizures characteristic of the X-linked myelin deficiency (md) mutation, which is ordinarily seen only in males. Cytogenetic study of two of these animals has shown them to have 41 chromosomes instead of the normal 42. The missing chromosome was identified as an X chromosome by G-banding analysis. These animals thus have an XO genotype comparable to that in Turner's syndrome. Anatomically, one of the animals, which was studied in detail, showed no abnormality of the uterus, and the ovaries, although somewhat smaller than normal, were histologically indistinguishable from those in a normal female rat. No evidence of endocardial fibroelastosis was detected, nor was there any anomaly of the aorta. The myelin deficiency in the central nervous system was comparable to that in hemizygous mutant male rats. XO monosomy in the Wistar rat thus has little effect on phenotype and is more comparable to that in mice than to Turner's syndrome in man. The myelin-deficient rat is useful for studies of X-chromosome monosomy since XO females can readily be identified by the neurological syndrome characteristic of the md mutation.

Animals↗

Different fatty-acid profiles in phosphoinositides from human fibroblastic meningiomas with or without chromosome 22 monosomy.

The fatty-acid composition of phosphoinositides derived from 13 human fibroblastic meningiomas, divided according to the presence or the absence of monosomy of chromosome 22, was analyzed. Phosphoinositides were separated into their 3 main components: phosphatidylinositol, phosphatidylinositol-4-phosphate, and phosphatidylinositol-4,5-bisphosphate. In all the tumors, regardless of cytogenetic differences, remarkable differences were detected between phosphatidylinositol and phosphatidylinositol-4-phosphate or phosphatidylinositol-4,5-bisphosphate. In meningiomas with 22 monosomy, there was a significant decrease in the relative amount of arachidonate in all the phosphoinositide fractions; this situation might determine diminished down-regulation of the corresponding diacylglycerol, derived by the phospholipase-C-stimulated hydrolysis of phosphoinositides, and, consequently, different protein-kinase-C stimulation.

Chromosome Aberrations↗

Hematologic and clinical features of patients with chromosome 5 monosomy or deletion (5q).

This paper analyzes the hematologic features and outcome of 13 patients with chromosome 5 abnormalities (monosomy 5 or deletion of 5q), either isolated or with additional anomalies. Among four patients with isolated del (5q), two had a stable refractory macrocytic anemia with thrombocytosis (5q-syndrome). All nine patients with complex karyotypes had acute leukemia or refractory anemia with excess of blasts in acute transformation; two cases were TdT-positive, with a lymphoid or a mixed phenotype. In seven patients, preleukemia preceded overt leukemia, and in six, a prior therapeutic, or occupational exposure to mutagens/carcinogens had occurred. Additional chromosome 7 abnormalities were seen in four cases. The median survival of patients with complex karyotypes was 19 months from the time of diagnosis of the hematologic disorder and 5 months from the time of identification of the chromosome 5 abnormality. Pathogenetic implications of the chromosome 5 monosomy or del (5q) through a proto-oncogene activation and the putative hemopoietic stem cell involvement in a clonal disease are discussed.

Adult↗

Prenatal diagnosis and molecular cytogenetic analysis of partial monosomy 10q (10q25.3-->qter) and partial trisomy 18q (18q23-->qter) in a fetus associated with cystic hygroma and ambiguous genitalia.

OBJECTIVES: To present the prenatal diagnosis and molecular cytogenetic analysis of a fetus with nuchal cystic hygroma and ambiguous genitalia. CASE AND METHODS: Amniocentesis was performed at 16 weeks' gestation because of the abnormal fetal sonographic finding of a large septated nuchal cystic hygroma. Genetic amniocentesis revealed a terminal deletion in the long arm of chromosome 10. The paternal karyotype was subsequently found to be 46,XY,t(10;18)(q25.3;q23). The maternal karyotype was normal. The pregnancy was terminated. A hydropic fetus was delivered with a septated nuchal cystic hygroma and ambiguous genitalia. Fluorescence in situ hybridization (FISH), microarray-based comparative genomic hybridization (CGH), and polymorphic DNA markers were used to investigate the involved chromosomal segments. RESULTS: FISH study showed absence of the 10q telomeric probe and presence of the 18q telomeric probe in the derivative chromosome 10. Microarray-based CGH analysis showed loss of distal 10q and gain of distal 18q. Polymorphic DNA marker analysis determined the breakpoints. The fetal karyotype was 46,XY,der(10)t(10;18)(q25.3;q23)pat. The chromosome aberration resulted in partial monosomy 10q (10q25.3-->qter) and partial trisomy 18q (18q23-->qter). CONCLUSIONS: The present case provides evidence that partial monosomy 10q (10q25.3-->qter) with partial trisomy 18q (18q23-->qter) can be a genetic cause of fetal cystic hygroma and ambiguous genitalia. Cytogenetic analysis for prenatally detected structural abnormalities may detect unexpected inherited chromosome aberrations.

Adult↗

Familial X centromere variant resulting in false-positive prenatal diagnosis of monosomy X by interphase FISH.

Interphase fluorescent in situ hybridization (FISH) analysis performed on uncultured amniotic fluid cells from a female fetus revealed a single signal using an X chromosome alpha-satellite probe, and the absence of any signal using a Y chromosome alpha-satellite probe. This result was initially interpreted as monosomy for the X chromosome in the fetus. Subsequent chromosome analysis from the cultured amniotic fluid cells showed two apparently normal X chromosomes. FISH using the X alpha-satellite probe on metaphase spreads revealed hybridization to both X chromosomes, although one signal was markedly reduced compared to the other. The same hybridization pattern was observed in the mother of the fetus. This is the first report of a rare familial X centromere variant resulting in a false-positive diagnosis of monosomy X by interphase FISH analysis for prenatal diagnosis.

Adult↗

Prenatal detection of monosomy 21 mosaicism.

We report a case of chromosomal mosaicism for monosomy 21 revealed in amniotic fluid cell culture. Ultrasound examination at 19 weeks' gestation showed in utero growth retardation and a complex cardiac malformation. A repeated amniocentesis confirmed the presence of monosomy 21 mosaicism. In view of the sonographically detected fetal abnormalities, termination of pregnancy was elected.

Abnormalities, Multiple↗

Relationship between the monosomy X phenotype and Y-linked ribosomal protein S4 (Rps4) in several species of mammals: a molecular evolutionary analysis of Rps4 homologs.

Two isoforms of the human ribosomal protein S4 gene, RPS4X and RPS4Y, are located on the X and Y chromosomes. It has been postulated that haploinsufficiency of these genes may contribute to Turner syndrome. We show here that several animal species that show the Turner-like phenotype on monosomy X have no Y-linked Rps4 homolog. There may be another gene(s) that contributes to abnormal phenotypes of monosomy X. Molecular evolutionary analysis shows that the Y-linked and RPS4X-related homologs diverged prior to the radiation of placental mammals and evolved independently. Furthermore, the functional constraints against the RPS4X-related homologs are much stronger than those against the Y-linked homologs.

Animals↗

Monosomy 21: a new case confirmed by in situ hybridization.

A new case of total monosomy 21 in a newborn is described. The diagnosis was first made using the cytogenetic data; it was then confirmed by the dosage of copper-superoxide dismutase (SOD-1) which showed a 50% decrease. In situ hybridization with a probe previously assigned to chromosome 21 was used to rule out the possibility of a partial monosomy with an unbalanced reciprocal translocation.

Chromosome Deletion↗

Cell culture studies on neurofibromatosis (von Recklinghausen). V. Monosomy 22 and other chromosomal anomalies in cultures from peripheral neurofibromas.

Cell cultures grown from peripheral neurofibromas of three patients suffering from sporadic peripheral neurofibromatosis (NF) were analysed cytogenetically at early in vitro passages. The NF-cultures exhibited a 6.7-fold higher frequency of aneuploid mitoses, including pseudodiploids, than the control cultures derived from the skin of three healthy donors. The predominant numerical anomaly was monosomy 22. Several, as yet unidentified marker chromosomes occurred in the NF-cultures, which also showed a much higher level of unstable chromosomal anomalies. The role of monosomy 22 in tumorigenesis of meningiomas and neurofibromas is discussed.

Cells, Cultured↗

Trisomy 4p and partial monosomy 18q due to paternal translocation t(4;18) (p11; q21.3).

A carrier status for balanced translocation in either of the parents increases the risk of congenital malformation in the offspring. A case of multiple congenital anomalies in a female newborn was found to be associated with trisomy 4p and partial monosomy 18q as a result of a reciprocal translocation, t(4; 18) (p11; q21.3) in the father. The clinical and cytogenetic findings are compared with characteristic features of trisomy 4p, monosomy 18q and two similar cases reported earlier.

Abnormalities, Multiple↗

Translocation breakpoint mapping and sequence analysis in three monosomy 1p36 subjects with der(1)t(1;1)(p36;q44) suggest mechanisms for telomere capture in stabilizing de novo terminal rearrangements.

Monosomy 1p36 results from a variety of chromosome rearrangements, including terminal deletions, interstitial deletions, derivative chromosomes, and complex rearrangements. Our previous molecular studies on a large cohort of monosomy 1p36 subjects suggest that a significant percentage of terminal deletions of 1p36 are stabilized by the acquisition of telomeric sequences from other chromosome ends, forming derivative chromosomes (i.e., "telomere capture"). However, the molecular mechanism(s) that results in and/or stabilizes terminal deletions of 1p36 by telomere capture is poorly understood. In this report, we have mapped the translocation breakpoints in three subjects with der(1)t(1;1)(p36;q44) chromosomes by fluorescence in situ hybridization (FISH). These results indicate that the breakpoint locations are variable in all three subjects, with no common 1p deletion or 1q translocation breakpoints. In addition, sequence analysis of the 1p and 1q breakpoint-containing clones did not identify homologous sequences or low-copy repeats in the breakpoint regions, suggesting that nonallelic homologous recombination did not play a role in mediating these rearrangements. Microsatellite marker analysis indicates that two of the three derivative chromosomes were formed by intra-chromosomal rearrangements. These data are consistent with a number of recent reports in other model organisms that suggest break-induced replication at the site of a double-strand break may act as a mechanism of telomere capture by generating nonreciprocal translocations from terminally deleted chromosomes. Alternative models are also discussed.

Chromosome Aberrations↗

Secondary acute non-lymphocytic leukemia with monosomy 7 arising 9 years after acute lymphoblastic leukemia in childhood.

We report a case of pediatric acute non-lymphocytic leukemia (ANLL) with monosomy 7 occurring in a child successfully treated for acute lymphoblastic leukemia (ALL) nine years earlier. Acquired monosomy 7 is currently recognized as a distinct therapy-related cytogenetic abnormality which nonrandomly occurs as a late complication of cytotoxic therapy used in the treatment of both malignant and nonmalignant disease. Most commonly, this occurs as a disorder of bone marrow morphology and function characterized as a myelodysplastic syndrome (MDS) or ANLL. This case report emphasizes the need for continued evaluation of long-term survivors of childhood cancer to identify and minimize therapy-related side effects without compromising successful management.

Antineoplastic Combined Chemotherapy Protocols↗

Monosomy 21 in two patients with acute nonlymphocytic leukemia.

Among 50 cases of acute nonlymphocytic leukemia (ANLL) with available cytogenetic data seen in our section since May 1988, two were found to carry a monosomy 21 abnormality which has been rarely reported in hematologic malignancies. The first case is a 58-year-old male with a diagnosis of AML, FAB M2, who died of refractory leukemia 9 months later. The other case is a 59-year-old female with AML, FAB M2. Complete remission was achieved initially but she died of sepsis 3 months later with no evidence of leukemic relapse. Monosomy 21 is not yet recognized as a nonrandom cytogenetic abnormality in ANLL, whereas its unusual predilection in AML, especially the FAB M2 or M4 categories, as noted in our study and others' reports, have raised this possibility. Further studies and the accumulation of new cases are needed in the hope of defining it as a subtype of ANLL.

Chromosomes, Human, Pair 21↗

Monosomy 20 in childhood acute lymphoblastic leukemia.

We report two cases of acute lymphoblastic leukemia (ALL) with loss of chromosome 20 as the only karyotypic abnormality detected in the blast cells. The first patient is a 12-year-old boy studied at diagnosis. He represents the only case of monosomy 20 in our series of 90 pediatric ALL successfully karyotyped at diagnosis. In the second patient, monosomy 20 was detected at the second hematologic relapse, 12 years after the initial diagnosis; cytogenetic studies were not performed at disease onset.

Bone Marrow Cells↗

Longitudinal cytogenetic study of metaphase and interphase cells in childhood monosomy 7 syndrome.

A 15-year-old male with myelodysplastic syndrome (MDS) characterized by monosomy 7 was cytogenetically evaluated by metaphase karyotyping and fluorescence in situ hybridization (FISH) of interphase cells at six different points during the course of his disease. At diagnosis, there was complete agreement between metaphase and interphase findings. Interphase analysis alone provided important cytogenetic information on the first specimens received following intensive combination chemotherapy and bone marrow transplantation where metaphase analyses were uninformative. The detection of a minor post-treatment monosomy 7 population by interphase but not metaphase studies may have identified minimal residual disease prior to recurrence of MDS. From this longitudinal study, it is concluded that metaphase and interphase cytogenetic analyses form complementary approaches and that use of both provides greater analytical power when appropriate chromosome markers are available.

Adolescent↗