Prenatal diagnosis of cri du chat (5p-) syndrome in association with isolated moderate bilateral ventriculomegaly.

A case of prenatally detected cri du chat syndrome (5p-) is reported. Amniocentesis was performed following an abnormal ultrasound finding of isolated moderate bilateral ventriculomegaly. The karyotype showed a terminal deletion of the short arm of chromosome 5 including the critical region 5p15 for cri du chat syndrome. This was confirmed by fluorescence in situ hybridisation (FISH). Isolated mild ventriculomegaly may be a non-specific marker for cri du chat syndrome.

Del(18p) shown to be a cryptic translocation using a multiprobe FISH assay for subtelomeric chromosome rearrangements.

We have previously described a fluorescence in situ hybridisation (FISH) assay for the simultaneous analysis of all human subtelomeric regions using a single microscope slide. Here we report the use of this multiprobe FISH assay in the study of a patient whose karyotype was reported by G banding analysis as 46,XX,del(18)(p11.2). Although the proband had some features suggestive of a chromosomal abnormality, relatively few of the specific features of del(18p) were present. She was a 37 year old female with mild distal spinal muscular atrophy (SMA), arthritis of the hands, an abnormal chest shape (pectus excavatum), and an unusual skin condition (keratosis pilaris). Reverse chromosome painting with degenerate oligonucleotide primer-polymerase chain reaction (DOP-PCR) amplified del(18p) chromosomes as a probe confirmed the abnormality as del(18p), with no evidence of any other chromosome involvement. Subsequently, the multiprobe FISH assay confirmed deletion of 18p subtelomeric sequence. However, the assay also showed that sequences corresponding to the 2p subtelomeric probe were present on the tip of the shortened 18p. The patient is therefore monosomic for 18p11.2-pter and trisomic for 2p25-pter, and the revised karyotype is 46,XX,der(18)t(2;18)(p25; p11.2). We believe that a proportion of all cases reported as telomeric deletions may be cryptic translocations involving other chromosome subtelomeric regions. Further studies such as this are necessary to define accurately the clinical characteristics associated with pure monosomy in chromosomal deletion syndromes.

Trisomy 15 associated with loss of the Y chromosome in bone marrow: a possible new aging effect.

Trisomy 15 as a single autosomal abnormality is a rare finding in hematological disorders and has not as yet been associated with any specific disease type. We report 20 cases of trisomy 15 observed in the bone marrow of patients referred for a suspected hematological malignancy. Most patients were elderly, and a marked male predominance was evident. Aneuploidy for the Y chromosome was observed in addition to +15 in 11 out of 15 male patients. A myelodysplastic disorder (MDS) was confirmed in six cases, and acute myeloid leukemia (AML) in one. There was no evidence of malignant hematological diseases in the remaining 13 patients. We propose that there may be an association between loss of the Y chromosome and trisomy 15 and that trisomy 15, like missing Y, may not always be a marker of malignancy, but may reflect an underlying age effect. The possibility that its presence may herald the development of a malignant condition cannot, however, be excluded.

Trisomy 13 and myeloid malignancy--characteristic blast cell morphology: a United Kingdom Cancer Cytogenetics Group survey.

We retrospectively report data on 28 patients with haematological malignancy and trisomy 13 (25 cases) or tetrasomy 13 (three cases) as the primary acquired cytogenetic change. Peripheral blood and/or bone marrow morphology was reviewed in 25/28 cases and the final diagnosis was as follows: AML M0 (11), AML M1 (6), AML M2 (2), AML M4 (2), AML M5b (1), AML M6 (1), RAEB-t (3), RAEB (1), RA (1). All three cases with tetrasomy 13 had AML M0. Characteristic small hand-mirror blasts with cytoplasmic blebs and tails and scanty small granules were seen in 13/25 cases and 18/25 cases had small blasts which could easily be mistaken for lymphoblasts. Trilineage dysplasia was present in 8/28 cases. Median patient survival was 3 months. We conclude that trisomy 13 is particularly associated with acute myeloid leukaemia with minimal differentiation (AML MO), often has distinctive morphological features, and has a poor prognosis.

Interstitial deletion of band 3q25.

Interstitial deletions of the long arm of chromosome 3 are rare. We report a man with an interstitial deletion involving band 3q25. To our knowledge, this is the first patient to be described with this cytogenetic abnormality.

Solid tissue culture for cytogenetic analysis: a collaborative survey for the Association of Clinical Cytogeneticists.

AIMS: To survey the diagnostic service provided by UK laboratories for the culture of solid tissue samples (excluding tumours) and in particular to examine the variation in culture success rates and the problems of maternal cell overgrowth. METHODS: Twenty seven laboratories took part in a collaborative survey during 1992. Each laboratory submitted data on up to a maximum of 60 consecutive specimens (n = 1361) over a six month period. RESULTS: Skin specimens, the largest category received (n = 520), were the most problematic (51% success rate). Culture success rates were significantly lower (43%) when skin specimens (n = 140) were transported dry to the laboratory. Success rates for skin specimens also varied, depending on the origin of the specimen, from 18% for intra-uterine deaths (IUD) (n = 94) to 85% for neonatal deaths (n = 33) and 83% for live patients (n = 54). Culture of selected extra-fetal tissues from IUD, stillbirths and following elective termination of pregnancy (TOP) gave comparable success rates to those achieved for skin samples from neonatal deaths and live births. Skewed sex ratios, female > male, were identified for products of conception (POC) (n = 298) and placental biopsy specimens (n = 97). CONCLUSIONS: By appropriate selection, transport and processing of tissues, and in particular by avoiding relying solely on skin samples from IUD, stillbirths and TOP, an increase in culture success rates for solid tissue samples submitted for cytogenetic analysis could be achieved. The high risk of maternal cell contamination from POC and placental biopsy specimens was also identified in this survey.

Constitutional and acquired trisomy 8.

Trisomy 8 is seen in a range of disorders both constitutional and acquired. The full constitutional condition presents with physical stigmata, skeletal abnormalities and a mild to moderately retarded IQ. Trisomy 8 is frequently seen as a mosaic in the blood or in the skin or both. Trisomy 8 as an acquired condition is found in haematological disorders, notably in myelodysplasia (MDS) and acute myeloid leukaemia (AML), and is restricted to the malignant cells. These arise in the bone marrow and may also be found in the peripheral blood. Reported in the issue (Zollino et al. (1995) Leukemia Res. 19(10), 733) is a case of a patient with constitutional trisomy 8 mosaicism who developed myelodysplasia with trisomy 8 in 95-100% of bone marrow cells. Here we consider the implications of this case to the diagnosis of both malignant and constitutional conditions.

Hematological features of patients with myelodysplastic syndromes associated with a chromosome 5q deletion.

The hematological and clinical features of 26 patients with myelodysplasia and a chromosome 5q deletion in the bone marrow are presented. We have examined the relationship of French-American-British Co-operative Group (FAB) 1982 classification and bone marrow karyotype at diagnosis with patient outcome and the presence or absence of the classical features of the 5q-syndrome. Those patients classified as refractory anemia (RA) with no additional karyotypic abnormalities have the typical features of the 5q-syndrome and a good prognosis. None of the patients in this group transformed to acute leukemia during the period of follow-up. Patients with either refractory anemia and excess blasts (RAEB) or additional karyotypic abnormalities show many of the hematologic features of the 5q-syndrome but do not share the good prognosis. We conclude that the 5q-syndrome may be best defined as primary MDS of the FAB type RA with a 5q deletion as the sole karyotypic abnormality. This simple definition will distinguish patients with a good prognosis and all the classical features of the 5q-syndrome.

Neurofibromatosis and childhood leukaemia/lymphoma: a population-based UKCCSG study.

There is a well-known raised risk of leukaemia in children with neurofibromatosis type 1 (NF-1). We carried out the first detailed population-based study of leukaemia and non-Hodgkin lymphoma (NHL) associated with NF-1 in order to estimate the risk and elucidate the relationship between these conditions. Over the 17 year study period there were five cases of chronic myelomonocytic leukaemia (CMML) in patients with NF-1 (relative risk 221; 95% CI 71-514), 12 cases of acute lymphoblastic leukaemia (ALL) (relative risk 5.4; 95% CI 2.8-9.4) and five cases of NHL (relative risk 10.0; 95% CI 3.3-23.4). Marrow cytogenetics could be reviewed for seven patients. Specific abnormalities found were monosomy 21 in a child with CMML and 7p+, 17p- in a child with ALL. No abnormalities were reported of 17q, which includes the NF1 gene. CMML occurred predominantly in boys, who also had a family history of NF-1. ALL and NHL were more often found in children with no previous family history.

Hirschsprung's disease associated with a deletion of chromosome 10 (q11.2q21.2): a further link with the neurocristopathies?

We report a patient with total colonic aganglionosis in association with a deletion of part of the long arm of chromosome 10: (del(10)(q11.2q21.2)). This deletion includes the ret proto-oncogene, which has recently been implicated in multiple endocrine neoplasia type 2A (MEN 2A). The possible links between Hirschsprung's disease and the neurocristopathies and the aetiological role of abnormalities of neural crest development in these conditions are discussed.

An economic appraisal of alternative pre-natal screening programmes for Down's syndrome.

The objective of this study was to evaluate economically a screening programme within the Oxford Regional Health Authority for Down's syndrome, based on maternal serum alpha fetoprotein, unconjugated oestriol and human chorionic gonadotrophin as well as maternal age (the triple test) against maternal age alone. The design of the study involved cost-effectiveness analysis of the triple test relative to the maternal age screening programme, and the main outcome measure was the cost per Down's birth avoided. It was found that the triple test is more cost-effective over a wide range of assumptions concerning detection rates and procedure costs. Indirect costs are important in considering the cost-effectiveness of the screening programmes. The most efficient detection rate is around 58 per cent for which the cost per Down's birth avoided is approximately 29,600 pounds if only direct costs are evaluated, 20,100 pounds if all NHS costs are considered and -49,800 pounds if all resource consequences are analysed. It may be concluded that screening for Down's syndrome using the triple test is cost-effective over a wide range of assumptions concerning detection rate and procedure costs. If all resource costs are considered, the programme is highly cost-effective in comparison with other health care interventions.

Complete and partial XY sex reversal associated with terminal deletion of 10q: report of 2 cases and literature review.

We describe 2 karyotypically male infants with terminal deletion of 10q and mental retardation, multiple phenotypic anomalies and abnormal genitalia. One [karyotype 46,XY, del(10)(q26.1)] had female external genitalia; the other [karyotype 46,XY,-10,+der(10)t (10;16)(q26.2;q21)] had an intersex phenotype. Of 8 males previously reported with terminal 10q deletion as the major or only cytogenetic abnormality, 2 had an intersex phenotype, and the others all had combinations of cryptorchidism, micropenis, and hypospadias. Terminal 10q deletions appear to be strongly associated with abnormal male genital development, and should be specifically searched for in the cytogenetic workup of such cases.

Characterization of three de novo derivative chromosomes 16 by "reverse chromosome painting" and molecular analysis.

We have analyzed three de novo chromosome 16 rearrangements--two with a 16p+ chromosome and one a 16q+--none of which could be fully characterized by conventional cytogenetics. In each case, flow karyotypes have been produced, and the aberrant chromosome has been isolated by flow sorting. The origin of the additional material has been ascertained by amplifying and labeling the DNA of the abnormal chromosome by degenerate-oligonucleotide-primer-PCR and hybridizing it in situ to normal metaphase spreads (reverse chromosome painting). Both 16p+ chromosomes contain more than 30 Mb of DNA from the short arm of chromosome 9(9p21.2-pter), while the 16q+ contains approximately 9 Mb of DNA from 2q37. The breakpoints on chromosome 16 have been localized in each case; the two breakpoints on the short arm are at different points within the terminal band, 16p13.3. The breakpoint on the long arm of chromosome 16 is very close to (within 230 kb of) the 16q telomere. Determination of the regions of monosomy and trisomy allowed the observed phenotypes to be compared with other reported cases involving aneuploidy for these regions.

Comparison of cytogenetic and restriction fragment length polymorphism analyses for the detection of loss of chromosome material in clonal hemopoietic disorders.

Loss of chromosome material, as manifested by monosomy or partial deletion, is commonly found in neoplastic cells. We have undertaken a systematic comparison of standard cytogenetic analysis and molecular analysis for the detection of such loss, using as a model loss of chromosome 7 in 72 patients with a clonal myeloid malignancy. A large number of probes was used to screen three regions of chromosome 7 for loss by restriction fragment length polymorphism (RFLP) analysis. There were nine cases in which loss of chromosome 7 was detected by both techniques, but seven in which loss was detected by only one of the methods, demonstrating the complementary nature of these two techniques.

Molecular studies of the fragile X syndrome.

We have studied families segregating for the fragile X syndrome for the presence of amplification of the CGG repeat sequence adjacent to the HpaII Tiny Fragment (HTF) island in the FMR-1 gene. We demonstrate that 138/143 fragile X positive, mentally retarded males show a characteristic smear of fragments corresponding to somatic variation in the amplification of the CGG sequence. In 7/8 normal transmitting males (NTM's), we show that there is a small amplification of sequence but no evidence for somatic variation. Defined mutated fragments in the size range found in NTM's are seen in daughters of NTM's. The daughters of these female carriers show either a defined fragment in the NTM size range, a defined larger fragment or a heterogeneous pattern of fragments. In the latter 2 cases the clinical phenotype of the females cannot easily be predicted, presumably because of variable X inactivation. In some families, the observed DNA genotype does not correlate with the phenotype; in others we demonstrate the occurrence of individuals with a mosaic DNA genotype. The implications of these data for diagnosis of the disease are discussed.

Karyotypic evolution in B-cell chronic lymphocytic leukaemia.

Sequential cytogenetic studies were performed on a minimum of two and a maximum of nine occasions (mean 3.6) on the peripheral blood leucocytes of 112 patients with B-CLL. On initial cytogenetic analysis, 58 had a normal karyotype and 64 had a clonal abnormality. Karyotypic evolution occurred in 18 patients (16%). There was no significant difference in the incidence of disease progression between patients with a stable karyotype and those who underwent karyotypic evolution. In only one patient was there a clear association between disease progression, a change in cell morphology and karyotypic evolution.

Cytogenetic Findings and Survival in B-cell Chronic Lymphocytic Leukemia. Second IWCCLL Compilation of Data on 662 Patients.

Chromosome analysis on CLL-cells from 649 patients revealed clonal changes in 311 cases (48%). The most common abnormalities were trisomy 12 (n = 112), and structural changes on the long arm of chromosome 13 (n = 62), most of them interstitial deletions or translocations involving 13q14, the site of the retinoblastoma gene. Complex karyotypes were associated with poor prognosis, although karyotypic changes rarely develop during the course of the disease. Among patients with single chromosomal abnormalities those with trisomy 12 had a poor survival, whereas those with structural changes on chromosome 13 had as good a prognosis as patients with a normal karyotype.

Correlation of chromosome abnormalities with laboratory features and clinical course in B-cell chronic lymphocytic leukaemia.

141 patients with B-cell chronic lymphocytic leukaemia (B-CLL) have been studied for a minimum of 12 months and a maximum of 25 years. 30 of 133 patients (32.5%) had greater than 10% FMC7 positive peripheral blood lymphocytes and 19 of 131 patients (14.5%) had a serum or urinary paraprotein. At presentation 88 patients were stage A0, 18 A1, 18 A2, 11 B and six C. 44 (31%) had progressive disease and 42 (30%) died during the study period. 63 patients had a normal karyotype, 75 a clonal abnormality and in three no metaphases were obtained. The finding of a complex karyotypic abnormality was significantly associated with lambda surface phenotype (P less than 0.01), the presence of greater than 10% FMC7 positive cells (P less than 0.025), and the presence of a paraprotein (P = 0.025). Patients whose leukaemic cells had a complex karyotype and those with structural abnormalities of chromosomes 14 and 6 required treatment earlier than those with a normal karyotype.

Prognostic factors in stage AO B-cell chronic lymphocytic leukaemia.

85 patients presenting to a single centre with stage AO B-cell chronic lymphocytic leukaemia (B-CLL) have been studied. The duration of follow-up has ranged from a minimum of 1 year to a maximum of 18 years with a mean of 6 years. 14 patients have had progressive disease and 23 patients have died, of whom nine had CLL-related deaths. We assessed the prognostic significance of the following parameters: age at presentation, sex, haemoglobin concentration, initial lymphocyte count, surface membrane phenotype, serum immunoglobulin levels at presentation and karyotype. None of these factors were predictive of survival, but there was a correlation between initial lymphocyte count, surface immunoglobulin MD lambda phenotype, and complex karyotypic abnormalities and disease progression. Two patients with a complex karyotype have been followed for more than 5 years without evidence of progression.