[GENOTYPE-PHENOTYPE CORRELATIONS BY SPECIFIC FOUNDER VARIANTS IN BRCA IN ISRAELI WOMEN].

INTRODUCTION: Hereditary breast and ovarian cancer (HBOC) is predominantly accounted for by pathogenic variants (PVs) in BRCA1/BRCA2 genes. Population screening for recurring PVs in Ashkenazi Jews (AJ) was incorporated into the Israeli health basket in 2020, increasing the identification of BRCA carriers. Information on cancer risks for each PV in Israel is limited. AIMS: To assess genotype phenotype correlations of recurring BRCA PVs in Israeli carriers. METHODS: A retrospective cohort of 3,478 BRCA carriers followed-up in 12 medical centers, comprising the HBOC Consortium, formed the basis of the study. Data were collected using the electronic database, and analyzed by Chi square, t-tests and Kaplan-Meier survival analysis. RESULTS: Overall, 2145 BRCA1, 1131 BRCA2, and 22 double heterozygote PV carriers were analyzed. BRCA1 carriers had more cases of cancer (53.1% vs. 44.8%, p<0.001), ovarian cancer (OC) (17.1% vs. 10.6%, p<0.001), younger age at breast cancer (BC) (45.4 ±11.6SD years vs. 49.1 ±11.1SD years, p<0.001) and OC diagnosis (52.8 ±10.1SD yrs. vs. 61±10.6SD yrs. p<0.001), and more family history of BC (64.5% vs. 59.0%, p<0.001) and OC (36.7% vs. 27.3%, p<0.001) compared with BRCA2 carriers. Carriers of BRCA15382insC had more BC and less OC than BRCA1185delAG: 46.4% vs. 38.6% and 12.9% vs. 17.6% (p<0.04), respectively. CONCLUSIONS: In our population, similar to others, BRCA1 carriers have higher cancer rates and earlier age at diagnosis compared with BRCA2 carriers. The two recurring BRCA1 PVs have different risks: 5382insC carriers had more BC; 185delAG carriers had more OC. Risk-reducing measures should be based on variant-specific cancer risk.

Age at diagnosis of cancer in 185delAG BRCA1 mutation carriers of diverse ethnicities: tentative evidence for modifier factors.

Germline pathogenic sequence variants (PSVs) in BRCA1 substantially increase risk for developing breast (BC) and ovarian cancer (OvC). Yet, incomplete penetrance suggests that modifier factors affect phenotypic expression of mutant BRCA1 alleles. Analysis of identical BRCA1 PSV carriers of diverse ethnicities may provide further evidence for modifier factors. Female carriers of the 185delAG BRCA1 PSV identified through high-risk clinics in Israel, and Manchester England from 1998-2018 were eligible. Data were retrieved from patients records and confirmed (in Israel) by cross referencing with the Israeli National Cancer Registry. Overall, 2503 female carriers were included: 1715 (71.4%) Ashkenazi Jews (AJ), 201 (8.3%) Iraqi Jews and 383 (15.9%) of mixed ethnicity. In 102 (4.2%) cases ethnicity could not be ascertained. Of Israeli AJ carriers 649 (37.8%), 256 (14.9%) and 62 (3.6%) were diagnosed with BC, OvC or both cancers, respectively. For the Iraqi Jews these frequencies were 76 (37.8%), 43 (21.4%), and 8 (3.98%), respectively. Age at diagnosis of BC in AJ and Iraqi Jews was 46.7 ± 12.3 years and 52.8 ± 12.2 years, respectively (p = 0.001). For OvC age at diagnosis for AJ was 53.5 ± 10.7 years and for Iraqi Jews 50.1 ± 8.8 years (p = 0.0027). No differences in these parameters were noted between English Jews (n = 110) and non-Jews (n = 32). Age at diagnosis of BC and OvC differs between AJ and Iraqi Jews who carry an identical BRCA1 PSV. This finding supports the existence of modifier factors that may be ethnic specific.

Uterine cancer in Jewish Israeli BRCA1/2 mutation carriers.

BACKGROUND: BRCA1/2 mutation carriers have an increased risk of developing ovarian cancer, leading to the recommendation of risk-reducing salpingo-oophorectomy (RRSO) at 35-40 years of age. The role, if any, that BRCA mutations play in conferring uterine cancer risk, is unresolved. METHOD: Jewish Israeli women, carriers of one of the predominant Jewish mutations in BRCA1/2 from 1998 to 2016, were recruited. Cancer diagnoses were determined through the Israeli National Cancer Registry. Uterine cancer risk was assessed by computing the standardized incidence ratio of observed-to-expected number of cases, using the exact 2-sided P value of Poisson count. RESULTS: Overall, 2627 eligible mutation carriers were recruited from 1998 to 2016, 2312 (88%) of whom were Ashkenazi Jews (1463 BRCA1, 1154 BRCA2 mutation carriers, 10 double mutation carriers). Among these participants, 1310 underwent RRSO without hysterectomy at a mean (± standard deviation) age of 43.6 years (± 4.4 years). During 32,774 women-years of follow up, 14 women developed uterine cancer, and the observed-to-expected rate of all histological subtypes was 3.98 (95% confidence interval [CI], 2.17-6.67; P < .001). For serous papillary (n = 5), the observed-to-expected ratio was 14.29 (95% CI, 4.64-33.34; P < .001), and for sarcoma (n = 4) it was 37.74 (95% CI, 10.28-96.62). These rates were also higher than those detected in a group of 1844 age- and ethnicity-matched women (53% with breast cancer). CONCLUSION: Israeli BRCA1 or BRCA2 mutation carriers are at an increased risk for developing uterine cancer, especially serous papillary and sarcoma. These elevated risks of uterine cancer should be discussed with BRCA carriers.

The yield of targeted genotyping for the recurring mutations in BRCA1/2 in Israel.

BACKGROUND: Hereditary breast cancer is predominantly associated with germline mutations in the BRCA1 or BRCA2 genes. A few recurring mutations in these genes were reported in ethnically diverse Jewish populations. Since 2013, most oncogenetic laboratories in Israel adopted a two-step approach for BRCA1/2 genotyping, where the first step is genotyping for 14 seemingly recurring mutations-first-pass genotyping. The aim of this study was to assess the yield of this targeted BRCA sequencing. METHODS: Clinical and genotyping data of all individuals who underwent oncogenetic counseling and first-pass BRCA genotyping at the Oncogenetic Service Sheba and Assaf Harofeh Medical Centers from 1 February 2013 to 30 June 2017 were reviewed. All study participants were unrelated to each other. RESULTS: Overall, 5152 oncogenetic tests were reviewed in the present study, of which 4452 had no a priori known familial mutation. The majority of participants (68.6%) were genotyped because of personal history of cancer; 20.6% were tested because of family history of cancer, and details for the remaining 10.7% were missing. Overall, 256/4452 (5.8%) carriers were detected, 141 BRCA1 and 115 BRCA2 mutation carriers. In 54% of cancer-free carriers, no clinically suspicious family history of cancer was ascertained. CONCLUSIONS: The currently used scheme of first-pass genotyping in Israel seems to have a high yield of mutation detection even in the absence of a significant family history of cancer. The challenge is to optimize the currently used targeted panel of common mutations and adjust it to the accumulating new data in the Israeli population.

Screening for germline mutations in breast/ovarian cancer susceptibility genes in high-risk families in Israel.

We evaluated the clinical utility of screening for mutations in 34 breast/ovarian cancer susceptibility genes in high-risk families in Israel. Participants were recruited from 12, 2012 to 6, 2015 from 8 medical centers. All participants had high breast/ovarian cancer risk based on personal and family history. Genotyping was performed with the InVitae™ platform. The study was approved by the ethics committees of the participating centers; all participants gave a written informed consent before entering the study. Overall, 282 individuals participated in the study: 149 (53 %) of Ashkenazi descent, 80 (28 %) Jewish non-Ashkenazi descent, 22 (8 %) of mixed Ashkenazi/non-Ashkenazi origin, 21 (7 %) were non-Jewish Caucasians, and the remaining patients (n = 10-3.5 %) were of Christian Arabs/Druze/unknown ethnicity. For breast cancer patients (n = 165), the median (range) age at diagnosis was 46 (22-90) years and for ovarian cancer (n = 15) 54 (38-69) years. Overall, 30 cases (10.6 %) were found to carry a pathogenic actionable mutation in the tested genes: 10 BRCA1 (3 non-founder mutations), 9 BRCA2 (8 non-founder mutations), and one each in the RAD51C and CHEK2 genes. Furthermore, actionable mutations were detected in 9 more cases in 4 additional genes (MSH2, RET, MSH6, and APC). No pathogenic mutations were detected in the other genotyped genes. In this high-risk population, 10.6 % harbored an actionable pathogenic mutation, including non-founder mutations in BRCA1/2 and in additional cancer susceptibility genes, suggesting that high-risk families should be genotyped and be assigned a genotype-based cancer risk.

Mosaic compound heterozygosity of SHOX resulting in Leri-Weill dyschondrosteosis with marked short stature: implications for disease mechanisms and recurrence risks.

Mutations or deletions in the SHOX gene cause Leri-Weill dyschondrosteosis (LWD) and Langer mesomelic dysplasia (LMD) when present in heterozygous or homozygous form, respectively. A new class of enhancer deletions was identified 30-250 kb downstream of SHOX. We identified a female patient with marked short stature, mosaic for monosomy X in 31% of her lymphocytes, and findings consistent with LWD. Additional molecular studies demonstrated segregation of 17 polymorphic markers flanking and including the SHOX locus, spanning 328 kb of pseudoautosomal region 1 (PAR1) region. A deletion up to 10 kb residing 197 kb downstream of SHOX gene was detected, which was germinally transmitted from her clinically unaffected father. This was associated with post-zygotic mosaic loss of the normal maternal X-chromosome, evidenced by fluorescent fragment analysis. Since most patients with LMD with deletions downstream of SHOX gene also have SHOX mutations in trans, it may suggest these deletions are associated with a milder phenotype. Further studies are required to elucidate the role of the former region in disease etiology. Mutations should be sought in clinically non-affected family members because of the variable expressivity in hemizygous carriers, and cytogenetic evaluation should be considered to detect possible X-chromosome rearrangements underlying the haploinsufficiency for the PAR1 when deletion is detected by molecular analysis. Similarly, when LWD and marked short stature occur in a patient with mosaic Turner syndrome, the possibility of mutations in SHOX and the downstream of SHOX gene should be considered.

Cone-rod dystrophy and a frameshift mutation in the PROM1 gene.

PURPOSE: To identify the genetic cause underlying autosomal recessive cone-rod dystrophy (CORD) and high myopia. METHODS: Nine members of a consanguineous Arab family were clinically examined and were given fluorescein angiography (FA), biometry, and full field electroretinogram (ERG) testing. Blood samples were collected for DNA extraction. A homozygousity genome-wide scan was performed using >382 polymorphic microsatellite markers on genomic DNA from three affected family members. Regions of homozygosity were further analyzed in all members of the family. Mutation analysis of the PROM1 gene was performed by direct sequencing of PCR-amplified exons. RESULTS: The phenotype is characterized by severe visual impairment evident in the first decade of life. Affected family members have bull;s-eye macular appearance, peripheral retinal pigment clumps, and cone-rod type ERG changes. Additionally, they have high myopia with axial lengths exceeding 25.3 mm. A genome-wide scan detected a region of 2.1 Mb on chromosome 4p that fully segregates with the disease within the family. This region encompasses the PROML1 gene, mutations of which have been implicated in retinal dystrophies. PROML1 mutation analysis identified a novel single nucleotide insertion at position 1629 of the cDNA resulting in truncation of approximately one-third of the protein. CONCLUSIONS: The mutation described in this report further expands the clinical spectrum of PROM1 mutations.

Dynamic modification strategy of the Israeli carrier screening protocol: inclusion of the Oriental Jewish Group to the cystic fibrosis panel.

PURPOSE: A retrospective population study was conducted to determine the carrier frequencies of recently identified mutations in Oriental Jewish cystic fibrosis patients. METHODS: Data were collected from 10 medical centers that screened the following mutations: two splice site mutations-3121-1G>A and 2751 + 1insT-and one nonsense mutation-the Y1092X in Iraqi Jews. One missense mutation, I1234V, was screened in Yemenite Jews. RESULTS: A total of 2499 Iraqi Jews were tested for one, two, or all three mutations. The 3121-1G>A, Y1092X, and 2751 + 1insT mutations had a carrier frequency of 1:68.5, 1:435, and 0, respectively. In 1435 Yemenite Jews screened, I1234V had a carrier frequency of 1:130. CONCLUSION: The 0.84% allele frequency of the three Iraqi founder mutations falls within the Israeli Society of Medical Geneticists' inclusion criteria for screening of 1:60 carrier frequency; hence, Iraqi Jews were added to the carrier screening policy with a panel including the three Iraqi founder mutations in addition to the five Ashkenazi mutations previously detected in Eastern Jews. 2751 + 1insT that was detected in patients only was included in the screening panel to increase the detection rate. I1234V does not meet the inclusion criteria but is now offered on a diagnostic basis and can be added to the screening panel for individuals whose mixed origin includes Yemenite, in addition to protocol-recommended origins. This study demonstrates the dynamic modifications of the Israeli carrier cystic fibrosis screening protocol based on newly detected founder mutations in a large cohort, taking into account mutation impact and intercommunal admixture.

Vertical transmission of a mutation in exon 1 of the WT1 gene: lessons for genetic counseling.

We present a vertical transmission of a nonsense mutation in exon 1 of the Wilms' tumor WT1 gene, from a mother who had Wilms' tumor in infancy and decreased fertility at adulthood, to her son who displayed genitourinary (GU) anomalies, gonadal dysgenesis with gonadoblastoma foci, and intra-abdominal Mullerian derivatives. No Wilms' tumor was detected up to the age of 6 years in the son. Sequence analysis of constitutional DNA of the WT1 gene revealed a heterozygous c.327C > A sequence change in exon 1 leading to a premature stop codon at amino acid 109. This mutation demonstrates the lack of correlation between genotype-phenotype and mutation position in the WT1 gene, the presence of intra-familial variability, and the effect of gender on severity of GU anomalies. We suggest that detection of a GU defect in the presence of parental history of Wilms' tumor be followed up by screening of constitutional DNA for WT1 mutations. Explorative laparoscopy for sex organ evaluation and gonadal assessment for possible gonadoblastoma should be considered when constitutional mutation is detected in males with GU anomalies.

Prenatal diagnosis of sex chromosome abnormalities: the 8-year experience of a single medical center.

OBJECTIVE: To assess the indications for prenatal karyotyping of sex chromosomal abnormalities (SCAs) during pregnancy. METHODS: All singleton pregnancies interrupted in our institute because of SCAs (1998-2005) were categorized into subgroups of 45,XO (Turner syndrome), 47,XXY (Klinefelter syndrome), 47,XXX and 47,XYY. The indications for prenatal diagnostic testing were recorded. RESULTS: There were 67 SCAs pregnancies: 33% Turner syndrome, 28% Klinefelter syndrome, 21% 47,XXX and 18% 47,XYY. Maternal age was similar among the 4 groups (34 +/- 5, range 25-42 years). The main indications for fetal karyotyping were abnormal Down's syndrome (DS) screening or ultrasound findings, advanced maternal age (> or =35 years), and parental request. About 2/3 of the Turner and 47,XYY cases had either abnormal DS screening tests or sonographic findings, such as: increased nuchal translucency, mainly cystic hygroma and fetal hydrops. However, fetal karyotyping in more than 2/3 of the 47,XXX and 47,XXY cases was mainly performed because of advanced maternal age, and the diagnosis of fetal SCAs was coincidental (p <0.03). CONCLUSIONS: Our recent suggestion to expand the DS screening capacity to other chromosomal abnormalities including SCAs is further supported. Prenatal detection seems to be promising for Turner syndrome and possibly for 47,XYY syndrome, while other SCAs are less likely to be detected either by ultrasound or biochemical screening.

The best marker combination using the integrated screening test approach for detecting various chromosomal aneuploidies.

AIMS: To evaluate the cross-trimester multiple marker correlation and the minimum marker combination needed for detecting various chromosomal aneuploidies. MATERIALS AND METHODS: Parturient women with singleton pregnancies who underwent non-interventional sequential screening test and followed prospectively were recruited. They all underwent first trimester combined nuchal translucency (NT), pregnancy-associated plasma protein-A (PAPP-A), and free beta-human chorionic gonadotrophin (f-betahCG), followed by second trimester measurement of unconjugated estriol (uE3), human chorionic gonadotrophin (hCG) and alpha-fetoprotein (AFP). Pearson correlation was applied to compute any cross-trimester marker correlation and logistic regression analysis was used to determine the minimum marker combination for detecting various categories of chromosomal aneuploidies. RESULTS: The current study included 552 normal and 43 chromosomal-affected pregnancies (24 Down's syndrome [DS], 7 Turner's syndrome, 8 Edward's syndrome, 4 Klinefelter syndrome and 5 triploidy) for which the results of both the screening tests and the pregnancy outcome were available. In the normal cases, a significant correlation was found between f-betahCG and hCG (r=0.52), as well as between PAPP-A and uE3 (r=0.174). In DS pregnancies, the NT correlated with both hCG (r=0.45) and uE3 (r=-0.39). In Turner's syndrome, uE3 correlated both with PAPP-A (r=0.97) and f-betahCG (r=0.97). No other significant correlations were found. Furthermore, with the exception of f-betahCG and hCG in the unaffected cases, all other markers correlation appeared very weak. For detecting all the above categories of aneuploidies, the combination of NT, PAPP-A and uE3 and the maternal age background risk were found adequate, with a 74% detection rate (DR) for a 5% false positive rate (FPR). For DS only, the combination of maternal age-related background risk and the combination of NT, PAPP-A, hCG and AFP yielded a 79% DR for a 5% FPR. CONCLUSIONS: The current study agrees with a previous report that, overall, there is no strong correlation between first and second trimester markers. The extension of the integrated test for detecting various categories of common chromosomal aneuploidies using NT, PAPP-A and uE3 deserves further evaluation.

Analysis of mesenchymal cells derived from an chondrodysplasia punctuate patient and donors.

Conradi-Hunermann syndrome (CDPX2) is X-linked dominant disorder appeared with aberrant punctuate calcification. The skeletal cells derived from the marrow stroma are active in maintaining the skeletal formation. We obtained mesenchymal stem cells from a patient with CDPX2 and studied the formation of colony forming unit-fibroblast (CFU-F) in vitro in comparison cells obtained from normal donors. Cultured cells were studied morphologically and subjected to gene expression analysis. Marrow stromal cells (MSC)-chondrodysplasia punctuate (CDP) cells from CDPX2 were identified by their mosaic morphology formed three phenotypically distinct types of CFU-F colonies. One type consisted of normal fibroblasts with developed cell body and cellular processes; the second type contained pathological small cells without processes; and the third type comprised of mixed cells. We compared gene expression by the MSC-CDP to cells from normal donors. Transcription factors analyzed proliferation potential were similar in both normal and mixed colonies of MSC-CDP and similar to normal MSCs. The message expression for cytokines and extra cellular matrix (ECM) proteins revealed similar expression for biglycan, osteocalcin, and osteonectin, while IL-6, IL-11, and M-CSF mRNA levels were significantly higher in normal cells than in MSC-CDP. Mixed cells had elevated levels for IL-6 and M-CSF mRNA, but expressed IL-11 at the normal range. The studied genes were expressed at lower levels by the pathological (MSC-CDP) cells compared to normal ones. Hence, MSC-CDP was demonstrated to display abnormal morphology and transcription of several investigated genes. This study further illuminates the basis of the mosaic pattern of mesenchymal cells derived from a patient affected with CDPX2, and their gene expression involvement.

Chorioangioma and its severe infantile sequelae: case report.

OBJECTIVE: This case report describes a rare clinical presentation of chorioangioma diagnosed prenatally because of raised-maternal serum (MS) alpha-fetoprotein. METHODS: A thirty-year-old woman gravida 2, para 1 was referred to the ultrasound unit at 18 weeks of gestation because of abnormal MS triple-test results. This included AFP level of 14.9 MoM; hCG of 3.42 MoM and uE3 of 1.01 MoM. A detailed anomaly scan revealed a singleton fetus with no sonographically detectable malformations and normal amniotic fluid. The placenta was posterior. A well-circumscribed, rounded, predominantly hypoechoic lesion near the chorionic surface measuring 5 x 5 cm and protruding into the amniotic cavity was detected. Color Doppler sonogram showed no blood flow within the mass, but clear fetal waveforms in its periphery were demonstrated, and the diagnosis of chorioangioma was made. The pregnancy was followed uneventfully until 35 weeks of gestation when polyhydramnios and severe fetal cardiomegaly developed. Labor was therefore induced. RESULTS: A euploid female, who had multiple diffuse cutaneous and liver angiomatosis was born. She died at the age of one month because of cardiac failure and infection. CONCLUSIONS: The present case alerts to the interrelationship between placental and fetal angiomas. This may lead to severe infantile sequelae because of similar lesions.

Prenatal diagnosis of Down syndrome: ten year experience in the Israeli population.

Second trimester maternal serum biochemical markers, introduced between 1990 and 1995, were supplemented with new ultrasound methods at 14-16 weeks and first trimester biochemical markers between 1995 and 2000. This study evaluated the effectiveness of a Down syndrome (DS) prevention program among the Israeli Jewish population between 1990 and 2000. We collected data on the total number of prenatal tests performed on Israeli Jewish women, DS cases detected prenatally and DS livebirths in Israel during these years. We also studied the use of the newer screening tests in 1990, 1992, and 2000. Between 1990 and 1995, use of chromosomal studies for DS in this population increased from 11.3% to 21.6% and the percentage of cases detected prenatally from 53% to 70%. However, between 1996 and 2000, even with the new screening methods, the utilization rate remained similar (20.7% and 19.8%, respectively) and the percentage detected prenatally decreased to 61% in 2000. The total cost per case detected increased from $47,971 US dollars in 1990 to $75,229 US dollars in 1992, and to $190,171 US dollars in 2000. Between 1990 and 1995, improvement in the percentage of cases detected prenatally was associated with a significant increase in the amniocentesis rate-both are attributed to the introduction of second trimester maternal serum biochemical marker tests. Unexpectedly, the introduction between 1995 and 2000 of new genetic methods to assess the DS risk did not improve the percentage detected or reduce the amniocentesis rate, and was accompanied by an increased cost per case detected.

Modified allelic replication in lymphocytes of patients with neurofibromatosis type 1.

Transcription activity of genes is related to their replication timing, accordingly gene activation is coupled with a shift from late replication to early replication and vice versa. The relationship between replication timing and gene expression is best manifested by monoallelically expressed genes which show an asynchronous pattern of allelic replication, with the active allele replicating earlier than the inactive counterpart. Biallelically expressed genes, which normally replicate highly synchronously, when present in lymphocytes derived from patients with various types of malignancies or premalignancies, replicate highly asynchronously, similar to monoallelically expressed genes. Since neurofibromatosis-type 1 (NF1) patients are at an increased risk to develop malignancies, we used the fluorescence in situ hybridization (FISH) replication assay and evaluated the level of replication synchrony of three cancer-implicated genes (RB1, AML1, and CMYC) in lymphocytes derived from patients with NF1 without malignancy. Each gene, which normally displayed synchrony in allelic replication, in the patients' cells displayed loss of synchrony. The loss of replication synchrony, of each gene, in the patients' cells was achieved by an advanced replication of a single allele, which replicated remarkably earlier than its normal scheduled timing. In addition, the second allele showed slightly earlier replication timing than that normal for the gene. Thus, it is assumed that the NF1 condition is associated with activation of cancer-implicated genes that may be the cause for increased risk of patients to develop malignancies. As loss of synchrony in allelic replication timing differentiates well between NF1 patients and control subjects, this marker may have a potential use for identification of presymptomatic carriers of NF1 disorders.

Asynchronous replication of alleles in genomes carrying a microdeletion.

BACKGROUND: While most allelic pairs of DNA replicate synchronously during the S phase of the cell cycle, some genes normally replicate asynchronously, i.e., genes on the X chromosome and imprinted genes. The replication control mechanism is unknown but was shown to be impaired in malignancies and chromosomal trisomies where replication pattern becomes asynchronous. OBJECTIVES: To determine the level of asynchronization in replication timing of cells from patients with microdeleted genomes. METHODS: We applied monocolor fluorescent in situ hybridization with different probes on leukocytes from microdeleted genomes. RESULTS: All samples derived from the microdeleted genomes showed significantly higher levels of an asynchronized pattern compared to normal individuals. CONCLUSIONS: Even a "small" genetic imbalance (microdeletion) can interfere with gene replication and cell cycle progression, as previously shown in full trisomies.

Wiedemann-Beckwith syndrome: further prenatal characterization of the condition.

We describe three unrelated cases of Wiedemann-Beckwith syndrome (WBS). Two of them were diagnosed postnatally while the third was detected during pregnancy that resulted in elective termination. Amniotic karyotypes were normal in all. PCR amplification of polymorphic loci mapping to 11p15.5 region documented partial trisomy of 11p15.5 due to paternal translocation in one, and segmental and mosaic segmental unipaternal disomy (UPD) in the second and third cases, respectively. Based on findings documented in these cases and the literature, we tabulated the anomalies that might be detected prenatally by ultrasound and that may suggest the syndrome. Constant findings included fetal overgrowth, polyhydramios, enlarged placenta, and specifically a distended abdomen. As most described signs developed after 22 weeks of gestation, a careful follow-up should be carried on until late stages of pregnancy. An amniotic karyotype might not detect subtle chromosomal rearrangements. We therefore recommend utilizing PCR of polymorphic loci on 11p15.5, in addition to conventional cytogenetic analysis of the fetus and both parents to detect possible maternal deletions or inversions, paternal duplications, and UPD that may account for the largest subset of sporadic WBS reaching 25% of cases. An early diagnosis of WBS is important for counseling the parents concerning potential risk for developing embryonic tumors, selection of the mode of delivery due to potential adrenal cysts that might bleed during labor, and prevention of neonatal hypoglycemia.

Asynchronous replication of biallelically expressed loci: a new phenomenon in Turner syndrome.

PURPOSE: Transcriptional activity of genes is related to their replication timing; alleles showing the common biallelic mode of expression replicate synchronously, whereas those with a monoallelic mode of expression replicate asynchronously. Here the level of synchronization in replication timing of alleles was determined in subjects with Turner syndrome. METHODS: Fluorescence in situ hybridization was used for three loci not linked to X chromosome, in lymphocytes derived from 12 controls, 3 individuals with Turner, and 4 with mosaic Turner syndrome. RESULTS: In cells derived from controls, each pair of alleles replicated synchronously; yet these same alleles replicated asynchronously in cells monosomic for X chromosome derived from Turner and mosaic Turner patients. When the level of 45,X was low in the mosaic samples, the replication pattern of the 46,XX cells was normal. However, in samples with a high level of mosaicism, a significantly increased asynchronous replication was detected in the 46,XX cells. CONCLUSION: An altered temporal replication control in Turner syndrome affecting the aneuploid and euploid cells is shown. This alteration may potentially be involved in the determination of the syndrome.