Acute Monoblastic Leukemia with t(9;11) in a Patient Receiving Chemotherapy for Ovarian Cancer: Secondary Leukemia or Fortuitous Association of Two Neoplasias?

We describe the clinical course of a 61 years old patient who developed fulminant acute monoblastic leukemia (MSA, FAB) while still on systemic chemotherapy for an advanced adenocarcinoma of the ovary. The leukemia developed following chemotherapy with Cyclophosphamide and Cisplatin (9 cycles), and then Cyclophosphamide and Carboplatin (6 cycles) resulting in a partial remission of the ovarian tumor. Survival from the onset of acute leukemia was extremely short and the cause of death was intracerebral bleeding. Cytogenetic analysis of the leukemic cells revealed a 9:11 translocation, a pattern usually occurring in de novo leukemias. The literature on the association of solid tumors, particularly ovarian cancer, with acute leukemia is reviewed; while systemic chemotherapy for ovarian cancer definitely increases the risk of secondary leukemia, especially if alkylating agents are administered, the occurrence of leukemia during the administration of chemotherapy for the solid tumor is distinctly unusual. Our patient seems to be an additional example of a recently described therapy-related variant of acute leukemia developing shortly after the onset of chemotherapy and characterized by a rapidly downhill clinical course, a monocytic lineage and a cytogenetic rearrangement t(9;11)(p22;q23). While the number of these newly described cases is still small, this additional example should increase the awareness of this potential association in Cisplatin-treated patients.

Preimplantation genetic diagnosis for BRCA1/2--a novel clinical experience

OBJECTIVE

To describe our 2-year experience with preimplantation genetic diagnosis (PGD) for carriers of mutations in the genes BRCA1 and BRCA2, the dilemmas incurred and the lessons learned.

METHODS

We collected data on those carriers of BRCA1/2 mutations who applied for PGD counseling and who decided to proceed. We describe the PGD procedures that were conducted and their outcome.

RESULTS

Ten carriers of BRCA1/2 mutations applied for PGD counseling, seven were healthy, and three were BC survivors. Eight women needed in vitro fertilization (IVF) because of coexisting infertility. After counseling, six opted for the procedure and five of them underwent PGD for the BRCA mutation. In one of these PGD, fluorescence in situ hybridization (FISH) analysis for chromosomes 21, X and Y was also performed. Three women conceived, each in the first treatment attempt. One of them gave birth to twins, the second to a singleton and the third is currently pregnant. During the pregnancies, dilemmas concerning PGD confirmation were discussed.

CONCLUSIONS

PGD is an acceptable reproductive option for BRCA mutation carriers, especially for those who require IVF due to fertility problems. Discussion of this option should be carried out with sensitivity, taking into account the age of the woman, her health, fertility status and emotional state. Confirmatory prenatal diagnosis may not always be encouraged.

Glutathione-S-transferase M1, T1 and P1 polymorphisms, and breast cancer risk, in BRCA1/2 mutation carriers

Variation in penetrance estimates for BRCA1/2 carriers suggests that other environmental and genetic factors may modify cancer risk in carriers. The GSTM1, T1 and P1 isoenzymes are involved in metabolism of environmental carcinogens. The GSTM1 and GSTT1 gene is absent in a substantial proportion of the population. In GSTP1, a single-nucleotide polymorphism that translates to Ile112Val was associated with lower activity. We studied the effect of these polymorphisms on breast cancer (BC) risk in BRCA1/2 carriers. A population of 320 BRCA1/2 carriers were genotyped; of them 262 were carriers of one of the three Ashkenazi founder mutations. Two hundred and eleven were affected with BC (20 also with ovarian cancer (OC)) and 109 were unaffected with BC (39 of them had OC). Risk analyses were conducted using Cox proportional hazard models adjusted for origin (Ashkenazi vs non-Ashkenazi). We found an estimated BC HR of 0.89 (95% CI 0.65-1.12, P=0.25) and 1.11 (95% CI 0.81-1.52, P=0.53) for the null alleles of GSTM1 and GSTT1, respectively. For GSTP1, HR for BC was 1.36 (95% CI 1.02-1.81, P=0.04) for individuals with Ile/Val, and 2.00 (95% CI 1.18-3.38) for carriers of the Val/Val genotype (P=0.01). An HR of 3.20 (95% CI 1.26-8.09, P=0.01), and younger age at BC onset (P=0.2), were found among Val/Val, BRCA2 carriers, but not among BRCA1 carriers. In conclusion, our results indicate significantly elevated risk for BC in carriers of BRCA2 mutations with GSTP1-Val allele with dosage effect, as implicated by higher risk in homozygous Val carriers. The GSTM1- and GSTT1-null allele did not seem to have a major effect.

Laser-assisted derivation of human embryonic stem cell lines from IVF embryos after preimplantation genetic diagnosis

BACKGROUND

Human embryonic stem cells (hESCs) suitable for future transplantation therapy should preferably be developed in an animal-free system. Our objective was to develop a laser-based system for the isolation of the inner cell mass (ICM) that can develop into hESC lines, thereby circumventing immunosurgery that utilizes animal products.

METHODS

Hatching was assisted by micromanipulation techniques through a laser-drilled orifice in the zona pellucida of 13 abnormal preimplantation genetic diagnosed blastocysts. ICMs were dissected from the trophectoderm by a laser beam and plated on feeders to derive hESC lines.

RESULTS

eight ICMs were isolated from nine hatched blastocysts and gave rise to three hESC lines affected by myotonic dystrophy type 1, hemophilia A and a carrier of cystic fibrosis 405 + 1G > A mutation. Five blastocysts that collapsed during assisted hatching or ICM dissection were plated whole, giving rise to an additional line affected by fragile X. All cell lines expressed markers of pluripotent stem cells and differentiated in vitro and in vivo into the three germ layers.

CONCLUSIONS

These hESC lines can serve as an important model of the genetic disorders that they carry. Laser-assisted isolation of the ICMs may be applied for the derivation of new hESC lines in a xeno-free system for future clinical applications.

Rapid development of post-radiotherapy sarcoma and breast cancer in a patient with a novel germline 'de-novo' TP53 mutation

AIMS

Germline mutations in the TP53 tumour suppressor gene are associated with Li-Fraumeni syndrome, which is characterised by a spectrum of neoplasms occurring in children and young adults that predominantly include early-onset breast cancer, a variety of sarcomas, brain tumours and adrenocortical tumours. The identification of patients carrying TP53 mutations is primarily based on a positive family history of these early-onset characteristic cancer types. The aim of this study is to emphasize the importance of TP53 molecular testing in patients with very early onset breast cancer and no family history of cancer.

MATERIALS AND METHODS

A young woman with no family history of cancer presented with bilateral breast cancer at the age of 27 years. Forty months later she developed malignant fibrous histiocytoma of the right clavicle and another primary left breast cancer. Molecular testing of mutations 185delAG, 5382insC in BRCA1 gene and 6174delT in BRCA2 gene was performed using multiplex PCR and separation on a denaturing polyacrylamide gel. TP53 molecular analysis was performed by PCR-SSCP analysis of the whole coding region of the TP53. Exon 8 PCR products were sequenced using an ABI dye terminator kit and examined on an ABI 3100 automated sequencer.

RESULTS

Molecular testing of peripheral blood DNA did not reveal mutations in BRCA1 or BRCA2 genes. A novel germline TP53 mutation, c.G841C, p.D281N, was identified. The detected mutation is a missense substitution, c.G841C, resulting in the substitution of the amino acid aspartate to asparagine, p.D281N. Molecular analysis in her parents showed that neither of them carried the mutation.

CONCLUSIONS

We describe a novel 'de novo'TP53 mutation and discuss the importance of molecular testing in early-onset breast cancer patients and its effect on the management and outcome of the disease.

A single-nucleotide polymorphism in the RAD51 gene modifies breast cancer risk in BRCA2 carriers, but not in BRCA1 carriers or noncarriers

Variation in the penetrance estimates for BRCA1 and BRCA2 mutation carriers suggests that other genetic polymorphisms may modify the cancer risk in carriers. The RAD51 gene, which participates in homologous recombination double-strand breaks (DSB) repair in the same pathway as the BRCA1 and BRCA2 gene products, is a candidate for such an effect. A single-nucleotide polymorphism (SNP), RAD51-135g → c, in the 5′ untranslated region of the gene has been found to elevate breast cancer (BC) risk among BRCA2 carriers. We genotyped 309 BRCA1/2 mutation carriers, of which 280 were of Ashkenazi origin, 166 noncarrier BC patients and 152 women unaffected with BC (a control group), for the RAD51-135g → c SNP. Risk analyses were conducted using COX proportional hazard models for the BRCA1/2 carriers and simple logistic regression analysis for the noncarrier case–control population. BRCA2 carriers were also studied using logistic regression and Kaplan–Meier survival analyses. The estimated BC hazard ratio (HR) for RAD51-135c carriers adjusted for origin (Ashkenazi vs non-Ashkenazi) was 1.28 (95% CI 0.85–1.90, P=0.23) for BRCA1/2 carriers, and 2.09 (95% CI 1.04–4.18, P=0.04) when the analysis was restricted to BRCA2 carriers. The median BC age was younger in BCRA2-RAD51-135c carriers (45 (95% CI 36–54) vs 52 years (95% CI 48–56), P=0.05). In a logistic regression analysis, the odds ratio (OR) was 5.49 (95% CI 0.5–58.8, P=0.163). In noncarrier BC cases, carrying RAD51-135c was not associated with BC risk (0.97; 95% CI 0.47–2.00). These results indicate significantly elevated risk for BC in carriers of BRCA2 mutations who also carry a RAD51-135c allele. In BRCA1 carriers and noncarriers, no effect for this SNP was found.

Molecular diagnosis of FMF: lessons from a study of 446 unrelated individuals

BACKGROUND

Traditionally, the diagnosis of familial Mediterranean fever (FMF) has been based on clinical manifestations and the physician's experience. Following the cloning of the gene associated with this disease (MEFV), genetic analysis of its mutations has become available, providing a new tool for the establishment or confirmation of the diagnosis of FMF.

OBJECTIVES

We analyzed the results of molecular testing for MEFV mutations in 600 individuals. We wished to determine how many of them bore mutations and what percentage had clinically active FMF. We also compared the rate of genetic confirmation of the FMF diagnosis in referrals with suspected FMF seen by general practitioners with that of persons sent for genetic analysis by FMF experts.

METHODS

Of 600 individuals tested for FMF mutations, we analyzed separately 446 unrelated persons for the combination of their mutations, epidemiological data, and clinical manifestations. The five most common mutations in the present cohort were analyzed using the amplification refractory mutation system (ARMS).

RESULTS

Of the 446 subjects analyzed, 249 (55%) bore mutations: 147 of these were homozygotes or compound heterozygotes, all of whom had FMF according to clinical criteria. Of the remaining 102 heterozygotes, 72 had FMF according to clinical criteria. Two patients with none of the five mutations also had FMF: North African Jews bore mainly mutations M694V and E148Q. The M6941 mutation was found exclusively in Palestinian Arabs. The rate of confirmation of FMF diagnosis by mutation analysis in subjects sent by FMF experts was significantly higher than that of persons referred by general practitioners. Analysis of the molecular testing of the multicase families (154 individuals) revealed that 141 of them bore MEFV mutations and that 4 persons homozygous for E148Q were asymptomatic.

CONCLUSIONS

Molecular analysis of FMF mutations confirmed the diagnosis in about 60% of the referrals with suspected FMF. Some (33%) of the patients were heterozygotes, and there were also FMF patients with none of the 5 mutations analyzed. A second opinion by an FMF expert may decrease the need for mutation analysis in subjects suspected of having FMF.

A deletion mutation in GJB6 cooperating with a GJB2 mutation in trans in non-syndromic deafness: A novel founder mutation in Ashkenazi Jews

A deletion of at least 140 kb starting approximately 35kb upstream (telomeric) to the GJB2 (CX26) gene was identified in 7 patients from 4 unrelated Jewish Ashkenazi families with non-syndromic hearing loss. These patients were heterozygous for one of the common mutations 167delT or 35delG in the GJB2 gene in trans to the deletion. The deletion started at 5' side of the GJB6 (CX30) gene including the first exon and it did not affect the integrity of the GJB2 gene. The deletion mutation segregated together with the hearing loss, and was not found in a control group of 100 Ashkenazi individuals. We suggest that the deletion is a recessive mutation causing hearing loss in individuals that are double heterozygous for the deletion and for a mutation in the GJB2 gene. The effect of the deletion mutation could be due to a digenic mode of inheritance of GJB2 and GJB6 genes that encode two different connexins; connexin 26 and connexin 30, or it may abolish control elements that are important in the expression of the GJB2 gene in the cochlea. Regardless which of the options is valid, it is apparent that the deletion mutation provides a new insight into connexin function in the auditory system. The deletion mutation was on the same haplotypic background in all the families, and therefore is a founder mutation that increases the impact of GJB2 in the etiology of prelingual recessive non-syndromic hearing loss in the Ashkenazi population.

CAG and GGC repeat polymorphisms in the androgen receptor gene and breast cancer susceptibility in BRCA1/2 carriers and non-carriers

Variation in the penetrance estimates for BRCA1 and BRCA2 mutations carriers suggests that other genetic polymorphisms may modify the cancer risk in carriers. A previous study has suggested that BRCA1 carriers with longer lengths of the CAG repeat in the androgen receptor (AR) gene are at increased risk of breast cancer (BC). We genotyped 188 BRCA1/2 carriers (122 affected and 66 unaffected with breast cancer), 158 of them of Ashkenazi origin, 166 BC cases without BRCA1/2 mutations and 156 Ashkenazi control individuals aged over 56 for the AR CAG and GGC repeats. In carriers, risk analyses were conducted using a variant of the log-rank test, assuming two sets of risk estimates in carriers: penetrance estimates based on the Breast Cancer Linkage Consortium (BCLC) studies of multiple case families, and lower estimates as suggested by population-based studies. We found no association of the CAG and GGC repeats with BC risk in either BRCA1/2 carriers or in the general population. Assuming BRCA1/2 penetrance estimates appropriate to the Ashkenazi population, the estimated RR per repeat adjusted for ethnic group (Ashkenazi and non-Ashkenazi) was 1.05 (95%CI 0.97-1.17) for BC and 1.00 (95%CI 0.83-1.20) for ovarian cancer (OC) for CAG repeats and 0.96 (95%CI 0.80-1.15) and 0.90 (95%CI 0.60-1.22) respectively for GGC repeats. The corresponding RR estimates for the unselected case-control series were 1.00 (95%CI 0.91-1.10) for the CAG and 1.05 (95%CI 0.90-1.22) for the GGC repeats. The estimated relative risk of BC in carriers associated with > or =28 CAG repeats was 1.08 (95%CI 0.45-2.61). Furthermore, no significant association was found if attention was restricted to the Ashkenazi carriers, or only to BRCA1 or BRCA2 carriers. We conclude that, in contrast to previous observations, if there is any effect of the AR repeat length on BRCA1 penetrance, it is likely to be weak.

A deletion/insertion mutation in the BRCA2 gene in a breast cancer family: a possible role of the Alu-polyA tail in the evolution of the deletion

Patients with breast and/or ovarian cancer were screened for gross rearrangements in the BRCA2 gene by Southern hybridization, with exon 10 and a fragment of exon 11 used as probes. One breast cancer patient with a positive family history had a 6.2-kb deletion including exons 12 and 13. The deletion breakpoint in intron 11 was in the 3' polyA tail of an Alu element, where a track of approximately 60 adenine nucleotide residues was inserted. Expansion of the Alu-polyA tail may have resulted from polymerase slippage during replication, representing a novel mechanism in which Alu elements mediate deletion/insertion mutations.

Contribution of connexin 26 mutations to nonsyndromic deafness in Ashkenazi patients and the variable phenotypic effect of the mutation 167delT

Twenty-seven unrelated Jewish Ashkenazi patients with nonsyndromic prelingual deafness (NSD) were analyzed for mutations in the coding sequence of the connexin 26 (Cx26) gene. Biallelic mutations were identified in 19 of the 27 patients (70.4%); 12 were homozygous for the mutation 167delT, 2 were homozygous for the mutation 35delG, and 5 were compound 167delT/35delG heterozygotes. In addition three patients were heterozygous with no second identified mutation in the Cx26 gene. Biallelic mutations in the Cx26 gene account for 83% of familial cases and 44% of the sporadic cases. Among 268 unselected Ashkenazi individuals, 20 were 167delT/N heterozygotes, giving an estimate of 7.5% carrier frequency. Based on the 167delT carrier frequency in three studies (including the present one), it is expected that 167delT/167delT homozygotes account for 70% of all patients with NSD (1 in 1300). The hearing capacity of 30 patients (probands and their sibs) with biallelic Cx26 mutations and at least one allele with 167delT demonstrated inter- and intrafamilial variability from profound to mild hearing impairment.

A large deletion mutation in the CFTR gene (3120+1Kbdel8.6Kb): a founder mutation in the Palestinian Arabs. Mutation in brief no. 231. Online

A deletion mutation of 8.6Kb in the CFTR gene, spanning the exons 17a, 17b and 18 was identified in 4 homozygous unrelated Palestinian CF patients. The patients were of various ethnic subgroups including Muslims, Christians and Druze. The deletion breakpoint occurred within an identical 4bp sequence in introns 16 and 18, and the mutation was defined as 3120+1Kbdel8.6Kb. A simple PCR based assay was designed and using this assay two compound heterozygote patients with the 3120+1Kbdel8.6Kb were identified. The 3120+1Kbdel8.6Kh hearing chromosomes had a common intragenic haplotype and variable flanking polymorphic markers, indicating that it is an ancient founder mutation.

X inactivation phenotype in carriers of Pelizaeus-Merzbacher disease: skewed in carriers of a duplication and random in carriers of point mutations

Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive disease caused by coding sequence mutations in the PLP gene, sub-microscopic duplications of variable sizes including the PLP gene or very rarely deletions of the PLP gene. We analysed the X inactivation pattern in blood of PMD female carriers with duplications and with point mutations. In the majority of duplication carriers (7/11), the X chromosome bearing the duplication was preferentially inactivated, whereas a random pattern of X inactivation was detected in point mutation carriers (3/3), a deletion carrier (1/1), affected females (4/4) who did not have a recognised mutation and normal control females. However 2/5 non-carrier female relatives of patients with a duplication, had skewed X inactivation. The skewed pattern of inactivation observed in most duplication carriers and not in mutation carriers suggests a) that there is selection against those cells in which the duplicated X chromosome is active and b) other expressed sequences within the duplicated region rather than mutant PLP may be responsible. Since the skewed X inactivation did not segregate with the disease in two families and the pattern of X inactivation was variable among the duplication carriers, the pattern X inactivation is an unsuitable diagnostic tool for female carriers of PMD.

The E148Q mutation in the MEFV gene: is it a disease-causing mutation or a sequence variant?

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent attacks of serositis. To date more then 18 mutations responsible for the disease were identified in the MEFV gene, one such a mutation is E148Q in exon 2 of the gene. While screening FMF patients for mutations in the MEFV gene, we have identified 2 individuals parents of 2 unrelated FMF patients, who were homozygous for E148Q mutation. Upon clinical examination they were absolutely disease free and therefore raised the possibility that this mutation is a benign polymorphism rather than a mutation causing disease. To further investigate the role of the E148Q in FMF we analyzed 25 parents of FMF patients and a control group of 70 individuals, Jews of Moroccan extraction to match for ethnicity of the patients. The rate of E148Q in the control group was 6.4%, being 7.8% among the patient group. Among the parents group (obligatory carriers), in addition to the 2 parents that were homozygous E148Q, in 2 families one of the parents was heterozygote for E148Q but transmitted the other allele (apparently with unknown FMF mutation) to the affected child. Two healthy sibs of one of the E148Q homozygous were also homozygous E148Q. These observations are not in accordance to the notion that E148Q is a mutation causing disease.

Cystic fibrosis mutations in Israeli Arab patients

Mutation analysis was performed on 42 unrelated Israeli Arab CF patients. The previously known mutations in this population, DF508, N1303K, G542X, 4010delTATT, and S549R(T>G), were identified in 57 CF alleles, leaving 28 CF alleles with unknown mutations. Screening of the coding sequence of the CFTR gene by a single strand conformation analysis (SSCA) and direct sequencing revealed three point mutations and two intragenic deletions, including 2183AA>G, R75X, S549R (A>C), 3120+1Kbdel8.6Kb and del(exon2). In the present sample of Israeli Arab patients, 12 mutations account for 92% of the CF alleles. The mutations DF508, N1303K, W1282X and 3120+1Kbdel8.6Kb were found in all Arab ethnic subgroups. The mutations G85E, R75X, 2183AA>G, and del(exon2) were confined to Muslim Arabs, and the mutations 4010delTATT, S549R(A>C) and G542X were confined to Christian Arabs. Hum Mutat 14:543, 1999.

A 28-kb deletion spanning D15S63 (PW71) in five families: a rare neutral variant?

Methylation analysis with probe PW71 (D15S63) is an established procedure to test patients suspected of having Prader-Willi syndrome or Angelman syndrome. Using this test, we have identified a 28-kb deletion spanning D15S63 in five independent families. Sequence analysis revealed identical breakpoints in all the families. The haplotype data are compatible with a common ancestral origin of the deletion in at least two families. The deletion was not found in 1, 000 unrelated controls. Although the deletion maps within the imprinting-center region, neither maternal nor paternal inheritance of the deletion appears to affect imprinting in proximal 15q. We conclude that the deletion is a rare neutral variant that can lead to false-positive results in the PW71-methylation test.

Clinical implications of fluorescence in situ hybridization analysis in 13 chronic myeloid leukemia cases: Ph-negative and variant Ph-positive

Thirteen chronic myeloid leukemia (CML) patients, 10 with variant Philadelphia (Ph) translocations and 3 Ph negative cases, were analyzed by fluorescence in situ hybridization (FISH) with the use of BCR and ABL cosmid probes and a chromosome 22 painting probe. In the variant Ph translocations, the BCR-ABL fusion gene was located on the Ph chromosome; in 1 CML Ph-negative patient, the BCR-ABL fusion gene was located on the Ph chromosome; and, in 2 patients, it was located on chromosome 9. The chromosome 22 painting probe was detected on the third-party chromosome of the variant translocation, and in none of the variant translocations was there any detectable signal on chromosome 9. In CML patients with clonal evolution of a simple Ph, a signal of the chromosome 22 painting probe was detected on the der(9) of the Ph translocation. It was concluded that the variant Ph translocations evolved simultaneously in a three-way rearrangement. The clinical parameters of the 13 patients were similar to those of a large group of CML patients with a simple Ph translocation. It is suggested that, to determine the prognosis of CML patients with a complex karyotype, FISH analysis with a chromosome 22 painting probe be performed.

Genetic testing of breast and ovarian cancer patients: clinical characteristics and hormonal risk modifiers

OBJECTIVES

Carriers of the mutations 185delAG and 5382insC in the BRCA1 gene and 6174delT in the BRCA2 gene have a substantial life-time risk for breast and ovarian cancers (BC and OC). The aim of the study was to identify the clinical features and the hormonal risk modifiers in mutation carriers and the implication in suggested guidelines for treatment decisions in BRCA1/2 carrier patients.

STUDY DESIGN

Breast and/or ovarian cancer patients from the Oncology and Cancer Genetic clinics were tested for the three Ashkenazi founder mutations: 87 patients were identified as carriers of one of these mutations. Clinical presentation and age at onset were correlated with the mutations, in patients with bilateral BC or BC and OC, the length of time that elapsed between the diagnosis of the two cancers was recorded. We compared BC and OC patients with regard to ages at menarche, first pregnancy and menopause, number of pregnancies and deliveries, the use of oral contraceptives, hormonal replacement therapy and fertility treatments.

RESULTS

The carriers of the three BRCA1/2 Ashkenazi founder mutations did not differ in clinical presentation nor age at onset. Forty-three patients (74.1%) of 58 BC patients were diagnosed between the ages 30 and 50, only four (6.9%) patients were diagnosed after age 60. Of BC patients diagnosed before age 35, 63.6% developed second BC as compared to 25.5% of those diagnosed after age 35. Ovarian cancer was diagnosed after age 45 in 89.7% of the patients, only one patient was diagnosed under the age of 40. Oral contraceptives use was documented in 61.3% of BC patients as compared to 11.8% of OC patients. Other hormonal factors did not differ between the two groups.

CONCLUSIONS

The carriers of the three Ashkenazi founder mutations should be considered at the same risk for BC and for OC and treatment options should be the same. Mutation carriers diagnosed with BC before the age of 35 are at a very high risk for developing second breast cancer. Most ovarian cancers in carriers were diagnosed after age 45, and prophylactic oophorectomy should be postponed to the age of 45. Oral contraceptives might elevate the risk of BC in mutation carriers.

Multiple chromosomal abnormalities in fulminant anaplastic myeloma

We describe a 58-year-old woman with anaplastic multiple myeloma and multiple chromosomal abnormalities. Her karyotype showed extreme hyperploidy with 77 chromosomes. Some of the aberrations were typical of multiple myeloma (+3, +5, +15, +19, +21, t(11;14)(q13;q32)), others were characteristic of the aggressive anaplastic myeloma (+8), t(11;14)(q13;q32), while three chromosomal abnormalities (t(11;20)(p11;q13); t(4;7)(q31;q11); and t(14;20)(q24;q13)) have not been, to the best of our knowledge, described previously in the literature. The fulminant course of the disease confirms the poor prognosis of multiple karyotypic abnormalities in myeloma.

A birth in non-mosaic Klinefelter's syndrome after testicular fine needle aspiration, intracytoplasmic sperm injection and preimplantation genetic diagnosis

Non-mosaic Klinefelter patients are generally azoospermic due to primary testicular failure. Nevertheless, in some cases, testicular spermatozoa may be recovered and utilized to fertilize oocytes via intracytoplasmic sperm injection (ICSI). As the risk for an increased number of gonosomes in these spermatozoa is unclear, preimplantation genetic diagnosis (PGD) may be attempted in the resulting embryos. In the present study, we report our experience with the combined approach of sperm retrieval by testicular fine needle aspiration (FNA), ICSI and PGD in seven consecutive non-mosaic Klinefelter individuals. In four patients, between one and five spermatozoa were retrieved in five out of nine consecutive attempts. In a fifth patient, only 10 round spermatids could be isolated. Mature spermatozoa were injected into a total of 16 metaphase-II oocytes, of which 11 (69%) remained intact. Two distinct pronuclei (2PN) were observed in four oocytes (36%) while a single pronucleus (1PN) was documented in two oocytes. Five cleavage stage embryos developed from the oocytes of two couples. Upon the request of one couple, their three embryos (two derived from 1PN oocytes) were transferred without PGD but pregnancy was not achieved. PGD by fluorescence in-situ hybridization (FISH) was performed in the two embryos of the other couple which were derived from normal fertilization. PGD results of one embryo were 18,18,X,X,Y, the embryo was not transferred and FISH analysis of the remaining blastomeres identified variable chromosome numbers in the nuclei. The second embryo was diagnosed as normal and was transferred, resulting in a successful pregnancy and birth. In conclusion, the results of this report indicate that a pregnancy and birth may be attained in azoospermic non-mosaic Klinefelter individuals by testicular FNA combined with ICSI. Due to the unknown risk of gonosomes aneuploidy in embryos from Klinefelter patients, PGD or prenatal diagnosis should be recommended.

Sporadic imprinting defects in Prader-Willi syndrome and Angelman syndrome: implications for imprint-switch models, genetic counseling, and prenatal diagnosis

The Prader-Willi syndrome (PWS) and the Angelman syndrome (AS) are caused by the loss of function of imprinted genes in proximal 15q. In approximately 2%-4% of patients, this loss of function is due to an imprinting defect. In some cases, the imprinting defect is the result of a parental imprint-switch failure caused by a microdeletion of the imprinting center (IC). Here we describe the molecular analysis of 13 PWS patients and 17 AS patients who have an imprinting defect but no IC deletion. Heteroduplex and partial sequence analysis did not reveal any point mutations of the known IC elements, either. Interestingly, all of these patients represent sporadic cases, and some share the paternal (PWS) or the maternal (AS) 15q11-q13 haplotype with an unaffected sib. In each of five PWS patients informative for the grandparental origin of the incorrectly imprinted chromosome region and four cases described elsewhere, the maternally imprinted paternal chromosome region was inherited from the paternal grandmother. This suggests that the grandmaternal imprint was not erased in the father's germ line. In seven informative AS patients reported here and in three previously reported patients, the paternally imprinted maternal chromosome region was inherited from either the maternal grandfather or the maternal grandmother. The latter finding is not compatible with an imprint-switch failure, but it suggests that a paternal imprint developed either in the maternal germ line or postzygotically. We conclude (1) that the incorrect imprint in non-IC-deletion cases is the result of a spontaneous prezygotic or postzygotic error, (2) that these cases have a low recurrence risk, and (3) that the paternal imprint may be the default imprint.

The mechanisms involved in formation of deletions and duplications of 15q11-q13

Haplotype analysis was undertaken in 20 cases of 15q11-q13 deletion associated with Prader-Willi syndrome (PWS) or Angelman syndrome (AS) to determine if these deletions arose through unequal meiotic crossing over between homologous chromosomes. Of these, six cases of PWS and three of AS were informative for markers on both sides of the deletion. For four of six cases of paternal 15q11-q13 deletion (PWS), markers on both sides of the deletion breakpoints were inferred to be of the same grandparental origin, implying an intrachromosomal origin of the deletion. Although the remaining two PWS cases showed evidence of crossing over between markers flanking the deletion, this was not more frequent than expected by chance given the genetic distance between proximal and distal markers. It is therefore possible that all PWS deletions were intrachromosomal in origin with the deletion event occurring after normal meiosis I recombination. Alternatively, both sister chromatid and homologous chromosome unequal exchange during meiosis may contribute to these deletions. In contrast, all three cases of maternal 15q11-q13 deletion (AS) were associated with crossing over between flanking markers, which suggests significantly more recombination than expected by chance (p = 0.002). Therefore, there appears to be more than one mechanism which may lead to PWS/AS deletions or the resolution of recombination intermediates may differ depending on the parental origin of the deletion. Furthermore, 13 of 15 cases of 15q11-q13 duplication, triplication, or inversion duplication had a distal duplication breakpoint which differed from the common distal deletion breakpoint. The presence of at least four distal breakpoint sites in duplications indicates that the mechanisms of rearrangement may be complex and multiple repeat sequences may be involved.

Sporadic phaeochromocytomas are rarely associated with germline mutations in the von Hippel-Lindau and RET genes

OBJECTIVE

von Hippel-Lindau (VHL) disease and multiple endocrine neoplasia type 2 (MEN2) are autosomal dominant cancer syndromes. In both conditions, phaeochromocytoma is a prominent feature. It has recently been suggested that phaeochromocytoma can be the presenting and sole clinical manifestation of these multi-organ syndromes. The aim of this study was to ascertain the incidence of VHL and MEN2 among patients with sporadic phaeochromocytoma by mutational analysis.

PATIENTS

Twenty-seven unrelated patients with biochemically and/or anatomically proven sporadic phaeochromocytoma were evaluated.

DESIGN AND MEASUREMENTS

Constitutional DNA obtained from the patients was analysed by single stranded conformational analysis (SSCP) for mutations within the VHL gene coding sequence and by denaturing gradient gel electrophoresis (DGGE) for predominant mutations in exons 10, 11 and 16 of the RET proto-oncogene. The incidence of patients positive for either VHL or RET germline mutations was assessed.

RESULTS

Twenty-six of 27 patients had normal SSCP patterns in all three VHL gene exon segments and only one patient, with an atypical clinical presentation, had an aberrant pattern in exon 3 which upon DNA sequencing was shown to harbor a G to A transversion mutation at nucleotide 695. All patients had normal RET exon 10, 11 and 16 DGGE migration patterns.

CONCLUSION

Most, if not all, patients with typical unilateral sporadic phaeochromocytoma do not have von Hippel-Lindau disease or MEN2. Thus, clinical and/or molecular investigation for von Hippel-Lindau disease and MEN2 in this patient population does not appear to be indicated.

Transient neonatal diabetes mellitus in a child with invdup(6)(q22q23) of paternal origin

An association between the rare condition of transient neonatal diabetes mellitus and either uniparental disomy for chromosome 6 or dup(6)(q22q23) raised the assumption that in this location on chromosome 6 there is an imprinted gene. We diagnosed diabetes that developed in a baby girl immediately after birth and resolved after 7 weeks of insulin treatment. Due to some minor dysmorphic features, we investigated her karyotype and identified invdup(6)(q22q23). The duplication spans at least 10 cM including the DNA sites DS270,S314,S1684 and S310. This case further supports the assumption that an imprinted gene exists on chromosome 6q22-23.

Intracytoplasmic sperm injection combined with preimplantation genetic diagnosis for the prevention of recurrent gestational trophoblastic disease

A strategy for the prevention of repeated molar pregnancies by using intracytoplasmic sperm injection (ICSI) coupled with preimplantation genetic diagnosis (PGD) with fluorescence in-situ hybridization (FISH) was developed. In this approach, complete moles which arise from dispermic fertilization are avoided by the use of ICSI. ICSI is followed by preimplantation selection against the transfer of 46,XX embryos, thus preventing complete moles resulting from a fertilization of an inactive oocyte, by a haploid X-bearing spermatozoon which subsequently duplicates. Triploid partial moles which arise mainly from dispermic fertilization may also be prevented by ICSI. The preimplantation confirmation of diploidy by FISH guards against triploid partial moles which may result from mechanisms other than dispermic fertilization. The employment of this strategy in an attempt to prevent a repeated event of molar pregnancy in a patient with a history of two previous episodes of gestational trophoblastic disease is reported.

The founder mutations 185delAG and 5382insC in BRCA1 and 6174delT in BRCA2 appear in 60% of ovarian cancer and 30% of early-onset breast cancer patients among Ashkenazi women

The mutations 185delAG, 188del11, and 5382insC in the BRCA1 gene and 6174delT in the BRCA2 gene were analyzed in 199 Ashkenazi and 44 non-Ashkenazi Jewish unrelated patients with breast and/or ovarian cancer. Of the Jewish Ashkenazi women with ovarian cancer, 62% (13/21) had one of the target mutations, as did 30% (13/43) of women with breast cancer alone diagnosed before the age 40 years and 10% (15/141) of those with breast cancer diagnosed after the age 40 years. Age at ovarian cancer diagnosis was not associated with carrier status. Of 99 Ashkenazi patients with no family history of breast and/or ovarian cancer, 10% carried one of the mutations; in two of them the mutation was proved to be paternally transmitted. One non-Ashkenazi Jewish ovarian cancer patient from Iraq carried the 185delAG mutation. Individual mutation frequencies among breast cancer Ashkenazi patients were 6.7% for 185delAG, 2.2% for 5382insC, and 4.5% for 6174delT, among ovarian cancer patients; 185delAG and 6174delT were about equally common (33% and 29%, respectively), but no ovarian cancer patient carried the 5382insC. More mutations responsible for inherited breast and ovarian cancer probably remain to be found in this population, since 79% of high-incidence breast cancer families and 35% of high-incidence breast/ovarian cancer families had none of the three known founder mutations.

Trisomy 2: confined placental mosaicism in a fetus with intrauterine growth retardation

In a pregnancy that was monitored due to increased risk for Down syndrome in the triple test, a normal karyotype was found in amniocentesis. Follow-up by serial ultrasound examinations revealed intrauterine growth retardation (IUGR) at 20 weeks of gestation. The parents decided to terminate the pregnancy and the karyotype of the placental fibroblasts was 47,XX,+2. Analysis of polymorphic markers of chromosome 2 demonstrated (a) that trisomy 2 was confined to the placenta (CPM), (b) that the trisomy 2 cell line was a result of a meiotic I error of paternal origin, and (c) that the fetal tissues with a normal karyotype were biparental disomy 2.

t(15;21)(q15;q22.1) pat resulting in partial trisomy and partial monosomy of chromosomes 15 and 21 in two offspring

Two sibs, carriers of unbalanced products of the translocation t(15;21)(q15;q22.1) pat, are described. The sister had Prader-Willi syndrome due to deletion 15 (pter > q15) and partial trisomy 21 (pter > q22.1); her brother had partial trisomy 15 (pter > q15) and partial monosomy 21 (pter > q22.1). The translocation breakpoint on chromosome 21 was located proximal to the SOD1 gene, within a region of 4.0 cM (2.3 Mb) between the loci D21S217 and D21S213. The correlations between the clinical presentation and the molecular findings of the two sibs are discussed in relation to other patients with partial trisomy and monosomy 21.

Microsatellite instability and p53 mutations in therapy-related leukemia suggest mutator phenotype

During the last decade the frequency of therapy-related acute leukemia (t-leuk) and myelodysplastic syndrome (t-MDS) has been increasingly observed. Over the past 15 years, we treated 56 patients with t-leuk who had received prior chemotherapy (39%), radiotherapy (11%), or both (45%). The drugs received included alkylating agents and topoisomerase II inhibitors. The primary tumors included hematological malignancies (49%) and solid tumors such as breast or ovarian cancer. The median age at diagnosis of the primary tumor was relatively young (43 years +/- 18). Twelve patients had more than one primary tumor and 31 patients had a family history of malignancy. Karyotypic abnormalities were found in 91% of the patients. Prognosis was uniformly poor, with an overall median survival of 10 months. Twelve of the 18 patients examined (67%) had a multidrug resistance phenotype. P53 genes of the leukemic cells, as well as the original tumors, were analyzed in 21 patients using polymerase chain reaction (PCR) with single-stranded conformation polymorphism analysis followed by sequencing. P53 mutations were identified in 38% of these patients, a relatively high prevalence compared with other forms of MDS or de novo acute myeloid leukemia. Mutations were nongermline and restricted to the leukemic cells. We identified different p53 mutations in the various primary tumors of individual patients. The presence of a mutator phenotype was assessed by PCR analysis of microsatellites in eight loci (one trinucleotide repeat sequence, four dinucleotide, and three mononuclear repeat sequences). Microsatellite instability in two to seven loci were found in 15 of 16 (94%) of the patients. This instability is compatible with a mutator phenotype, which predisposes the patients to the development of malignancies including t-leuk.

Renal pathology in WAGR syndrome

The Wilms' tumor-aniridia-genital anomalies-mental retardation (WAGR) syndrome is associated with an increased risk for developing Wilms' tumor. A right nephrectomy was performed following the diagnosis of Wilms' tumor in a 2-year-old girl with WAGR syndrome and chromosome 11, del 11p13. Pathologic examination revealed intralobar nephrogenic rests and a peripelvic multicystic mass, sharply delineated from the adjacent typical intralobar nephrogenic rests and renal parenchyma, which may represent a cystic Wilms' tumor (cystic partially differentiated nephroblastoma). We studied the expression of the H19 gene by in-situ hybridization performed on paraffin sections of the kidney. H19 is an imprinted maternally-expressed gene that is not translated to protein and functions as a regulatory RNA molecule. It is tightly linked with the paternally-imprinted gene of insulin-like growth factor 2. While IGF2 presumably plays a role in tumorigenesis of Wilms' tumor, H19 is not expressed in the majority of Wilms' tumors. The expression of H19 in the intralobar nephrogenic rests was found to be prominent in the component of the blastema and markedly reduced with differentiation to tubular structures similar to the fetal kidney. The differential diagnosis of hyperplastic intralobar nephrogenic rests from a small Wilms' tumor arising in intralobar nephrogenic rests is difficult. Complete understanding of the chain of molecular events occurring in the evolution of Wilms' tumors may lead to the development of tumor markers to be used on paraffin sections and so help in the differential diagnosis of hyperplasia versus malignant transformation.

Comparison of phenotype in uniparental disomy and deletion Prader-Willi syndrome: sex specific differences

Prader-Willi syndrome (PWS) results primarily from either a paternal deletion of 15q11-q13 or maternal uniparental disomy (UPD) 15. Birth parameters and clinical presentation of 79 confirmed UPD cases and 43 deletion patients were compared in order to test whether any manifestations differ between the two groups. There were no major clinical differences between the two classes analyzed as a whole, other than the presence of hypopigmentation predominantly in the deletion group. However, there was a significant bias in sex-ratio (P < .001) limited to the UPD group with a predominance (68%) of males. An equal number of males and females was observed in the deletion group. When analyzed by sex, several significant differences between the UPD and deletion groups were observed. Female UPD patients were found to be less severely affected than female deletion patients in terms of length of gavage feeding and a later onset of hyperphagia. Although these traits are likely to be influenced by external factors, they may reflect a milder presentation of female UPD patients which could explain the observed sex bias by causing under-ascertainment of female UPD. Alternatively, there may be an effect of sex on either early trisomy 15 survival or the probability of somatic loss of a chromosome from a trisomic conceptus.

Localization of two X-linked mental retardation (XLMR) genes to Xp: MRX37 gene at Xp22.31-p22.32 and a putative MRX gene on Xp22.11-p22.2

MRX genes of 2 families with X-linked mental retardation (XLMR) were localized by linkage analysis. In family A, the gene was mapped to Xp22.31-p22.32, with significant LOD scores to various Xp22 markers within a distance of 6 Mb between DXS1223 and DXS1224. The MRX gene of this family was designated MRX37. In a mentally retarded female who is a carrier of the MRX37 gene, a random pattern of X inactivation was demonstrated. In family B, a positive LOD score, although not significant (< + 2), was found with the marker DXS1202 at Xp22.11-p22.2.

dup(10q) lacking alpha-satellite DNA in bone marrow cells of a patient with acute myeloid leukemia

A marker chromosome was identified in leukemic cells on an AML patient. The G-banding pattern resembled on i(10q), but its centromeric position was not clear; in some cells it had a telocentric shape, in others a metacentric or acentric shape. The origin of the marker chromosome was confirmed by FISH, using chromosome-10-specific painting. To determine the centromeric position, C-banding and alpha-satellite probes were applied in FISH, and none of them gave a positive signal. Despite the absence of the centromeric alpha-satellite sequences and the constricted feature of the centromere, the essential centromeric activity was retained in this chromosome, namely, the separation of sister chromatids in anaphase.

A (R80Q) mutation in 17 beta-hydroxysteroid dehydrogenase type 3 gene among Arabs of Israel is associated with pseudohermaphroditism in males and normal asymptomatic females

Four isozymes of steroid 17 beta-hydroxysteroid dehydrogenase (17 beta HSD) encoded by different loci catalyze the reversible conversion of androstenedione to testosterone and that of estrone to estradiol. The 17 beta HSD type 3 (17 beta HSD3) isozyme is encoded by the 17 beta HSD3 gene on chromosome 9q22 and expressed only in testes. Inherited defects in the 17 beta HSD3 isozyme cause a form of male pseudohermaphroditism that is rare within the general population, but frequent among a highly inbred Arab population in the Gaza strip. A point mutation in exon 3, codon 80 of the 17 beta HSD3 gene, R80Q, caused by a single base substitution from CGG to CAG was identified in both alleles of 24 individuals from 9 extended Arab families from Gaza, Jerusalem, and Lod-Ramle. Twenty-one homozygotes were male pseudohermaphrodites (46,XY) with testicular 17 beta HSD3 deficiency, born with either female-looking external genitalia or various degrees of genital ambiguity. If not reassigned in infancy, they were reared as females until puberty, when marked virilization occurred, often leading to the spontaneous adoption of a male gender role. In contrast, the 3 homozygote females (46,XX) were asymptomatic, had normal internal and external genitalia and normal sexual development, and revealed no biochemical evidence of 17 beta HSD3 deficiency. The molecular pattern in these families is compatible with an autosomal recessive mode of inheritance that is sex dependent.

[Genetic counseling for families at high cancer risk]

About 5-10% of the most common cancers, such as breast, colon and melanoma, result from mutations in inherited predisposition genes. Recently some of these genes have been mapped or even cloned. These advances in cancer genetics have made more precise genetic counseling possible for cancer patients and their families. In our clinic for specific genetic counseling 180 families with a history of cancer were seen during a 10-month period. In counseling sessions, the family history was confirmed and interpreted, personal risk was estimated and the availability of molecular genetic testing was presented. Blood samples for DNA testing were drawn from those with certain criteria who wished to be tested. Instructions for early detection were also given, depending on the personal risk of cancer as compared to that of the general population.

Predominant 45,X,--Y karyotype in donor cells after allogeneic BMT: cytogenetic and molecular analysis

We describe two women; one (patient 1) with the diagnosis of acute myeloblastic leukemia (AML), the second (patient 2) with myelodysplastic syndrome (MDS). Both patients underwent allogeneic bone marrow transplantation (BMT), from their HLA-matched brothers. Cytogenetic analysis after the BMT revealed a chromosomal mosaicism in both patients, with the karyotype 46,XX/45,X with no sign of the Y chromosome. The origin of the clone with monosomy X was determined using cytogenetic analysis including heteromorphism and segregation of DNA polymorphic markers. The results led us to the conclusion that in both patients the origin of the 45,X clone was that of the donors. Patient 1 had MDS-like syndrome after the BMT and was stabilized in the chimeric state; to date she is doing well. Patient II also had MDS. However, in her case, it was her primary disease. The graft in patient II was rejected and she died 6 months after BMT.

Cystic fibrosis heterozygote screening in the Orthodox Community of Ashkenazi Jews: the Dor Yesharim approach and heterozygote frequency

In the community of the Orthodox Jews most of the marriages are arranged a screening program that is aimed at preventing the marriage of two carriers of autosomal recessive disorders is conducted by the Dor Yesharim organization. A random sample of 6,076 individuals of the Orthodox Jewish Ashkenazi community, were screened for the five mutations common in Ashkenazi patients (delta F508, W1282X, G542X, N1303K, 3849 + 10Kb C-->T). Two hundred thirty-two carriers were identified, giving a heterozygote frequency of 1:26. The relative frequencies of the individual mutations in the general population were comparable to those in the patients.

Familial pheochromocytoma associated with a novel mutation in the von Hippel-Lindau gene

We report a three generation, 25 member kindred with familial pheochromocytoma. Seven subjects of generations I and II had pheochromocytoma, in five of the seven, the tumors were bilateral, and in two of the seven, the tumors were both adrenal and extraadrenal. One patient also had a carotid body chemodectoma, and one patient had a malignant adrenal tumor and abdominal paraganglioma. In the patient with the chemodectoma, a cerebellar hemangioblastoma became manifest 25 yr after his initial diagnosis with pheochromocytoma, leading only then to a clinical diagnosis of von Hippel-Lindau disease (VHL). A mutational analysis of the VHL gene revealed a novel nucleotide 709 G-->T transversion present in all affected subjects and in four presymptomatic children. In familial pheochromocytoma the diagnosis of VHL should be considered, even when the formal criteria for diagnosis of the syndrome are lacking.

Machado-Joseph disease: correlation between the clinical features, the CAG repeat length and homozygosity for the mutation

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder associated with the expansion of a CAG trinucleotide repeat in the MJD1 gene located on 14q32.1. We confirmed that the CAG expansion caused MJD in a Yemenite Jewish family and demonstrated that most of the clinical variation among members of this family was due to the genotype of the affected individuals. Six patients who presented with an early onset (25 years) and severe disorder were found to be homozygous for the CAG expansion. Among 5 heterozygotes for the CAG expansion older than 40 years, one had neurological symptoms from the age of 45, while the others were asymptomatic. In one of the heterozygotes, no neurological symptoms were present when last examined at the age of 66. Homozygosity for the MJD1 mutation was the main cause of variability in this large family, however, other factors clearly played a role in the expression of the gene. We could demonstrate that homozygote sibs with similar expansion in both alleles had significant differences in disease severity. Gender did not affect the clinical expression in this family.

Familial café au lait spots: a variant of neurofibromatosis type 1

Café au lait spots (CALS) are a frequent and one of the early manifestations of neurofibromatosis 1 (NF1). However, there are patients with isolated CALS who do not meet the diagnostic criteria for NFI. There are several reports of families in which CALS are inherited as an autosomal dominant trait, without any other features of NFI. In one reported family with dominantly inherited CALS linkage to the NF1 locus was ruled out. In order to elucidate the relationship between familial CALS and NF1 further, we performed a linkage analysis in a large kindred with 11 subjects with CALS in three generations and established close linkage between CALS and five NF1 intragenic polymorphisms. We propose that in this family the trait of CALS is allelic to NF1, it is fully penetrant, and it does not confer a risk of other NF1 symptoms.

The carrier frequency of the BRCA1 185delAG mutation is approximately 1 percent in Ashkenazi Jewish individuals

Since BRCA1, the first major gene responsible for inherited breast cancer, was cloned, more than 50 unique mutations have been detected in the germline of individuals with breast and ovarian cancer. In high-risk pedigrees, female carriers of BRCA1 mutations have an 80-90% lifetime risk of breast cancer, and a 40-50% risk of ovarian cancer. However, the mutation stats of individuals unselected for breast or ovarian cancer has not been determined, and it is not known whether mutations in such individuals confer the same risk of cancer as in individuals from the high-risk families studied so far. Following the finding of a 185delAG frameshift mutation in several Ashkenazi Jewish breast/ovarian families, we have determined the frequency of this mutation in 858 Ashkenazim seeking genetic testing for conditions unrelated to cancer, and in 815 reference individuals not selected for ethnic origin. We observed the 185delAG mutation in 0.9% of Ashkenazim (95% confidence limit, 0.4-1.8%) and in none of the reference samples. Our results suggest that one in a hundred women of Ashkenazi descent may be at especially high risk of developing breast and/or ovarian cancer.

Highly variable incidence of cystic fibrosis and different mutation distribution among different Jewish ethnic groups in Israel

The incidence of cystic fibrosis (CF) and the frequency of disease-causing mutations varies among different ethnic and geographic populations. The Jewish population around the world is comprised of two major ethnic groups; Ashkenazi and non-Ashkenazi. The latter is further classified according to country of origin. In this study, we analyzed the incidence of CF and the distribution of CF mutations in the general Jewish population in Israel and in most of the Jewish ethnic subgroups. The disease frequency varies considerably among the latter. Among Ashkenazi Jews, the frequency of CF is 1:3300, which is similar to the frequency in most Caucasian populations. Among non-Ashkenazi Jews, the disease occurs at a similar frequency among Jews from Libya (1:2700), Georgia (1:2700), Greece and Bulgaria (1:2400), but is rare in Jews from Yemen (1:8800), Morocco (1:15000), Iraq (1:32000), and Iran (1:39000). So far, only 12 mutations have been identified in Israeli Jews, and this enables the identification of 91% of the CF chromosomes in the entire Jewish CF population. However, in each Jewish ethnic group, the disease is caused by a different repertoire of mutations. The frequency of identified mutations is high in Ashkenazi Jews (95%), and in Jews originating from Tunisia (100%), Libya (91%), Turkey (90%), and Georgia (88%). However, a lower frequency of mutations can be identified in Moroccan (85%), Egyptian (50%), and Yemenite (0%) Jews. For genetic counseling of a Jewish individual, it is necessary to calculate the residual risk according to ethnic origin. Carrier screening of healthy Jewish individuals is currently feasible for Ashkenazi Tunisian, Libyan, Turkish, and Georgian Jews. These results provide the required information for genetic counseling of Jewish CF families and screening programs of Jewish populations worldwide.