תוצאת חיפוש

Prenatal Down's Syndrome Screening at 10-14 Weeks Gestation using the Combined Nuchal Translucency and Maternal Serum Biochemistry: Preliminary Results

Ron Maymon^1*, Marina Bergman², Shmuel Segal²,  Eli Dreazen¹, Zwi Weinraub¹ and Arie Herman¹

¹Department of Obstetrics and Gynecology, Assaf Harofe Medical Center, Zerifin 70300 (affiliated with Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv), Israel. ²Department of Obstetrics and Gynecology, Barzilai Medical Center, Ashkelon (affiliated with Ben Gurion University, Be'er-Sheeba), Israel.

We report our preliminary experience of prenatal screening for Down's syndrome (DS) using nuchal translucency (NT) measurement combined with the serum biochemistry analysis of Free b-human chorionic gonadotropin (FbhCG) and pregnancy associated plasma protein A (PAPP-A) all measurement at 10-14 weeks of gestation.

Of the 358 parturient women which enrolled in the study, 9 cases were not included because of fetal anomalies or miscarriages. Thus the study group included 349 singleton pregnancies in which complete prenatal and infant follow-up was available.

Forty-four pregnant women were found to be screen positive (12.6%) and in 13 cases (27%) of them fetal chromosomal aneuploidies were diagnosed. Looking into the markers profile we found that the NT was a sensitive marker which was abnormally increased in all the fetal aneuploidies. Serum FbhCG was found to be a promising marker as well, being significantly elevated (2.26[0.86 multiple of the medians, MoM) in DS cases, and decreased (<0.5 MoM) in two cases of Edward's syndrome.

On the contrary, PAPP-A was found less sensitive, and its mean MoM values were not significantly different between DS versus euploid fetuses.

Our preliminary results support the promising success of DS screening using NT and FbhCG.

דב גפל (1,4), יצחק שפירר (2), יוסי הלל (3)

(1) המח' לרפואה פנימית ג', בי"ח ברזילי, אשקלון, (2) מכון ריאות, בי"ח אסף הרופא, צריפין, (3) המח' לגד"ש וגנטיקה, הפקולטה לחקלאות ברחובות, האוניברסיטה העברית, ירושלים, (4) בית הספר לתזונה, הפקולטה לחקלאות ברחובות, האוניברסיטה העברית, ירושלים

הגנום האנושי מורכב מ-3.2 מיליארד זוגות של נוקליאוטידים, אך רק כ-10% הם גנים תיפקודיים המקדדים לחלבונים. תפקיד שאר הרצפים אינו ברור וכנראה שחלקם משתתפים בבקרת הביטוי של הגנים התיפקודיים ובייצוב הכרומוסומים. בשנות ה- 60 של המאה ה-20, התגלו בדנ"א מיקטעים הנשנים מספר רב של פעמים ולכן נהוג לכנותם סטליטים (DNA satelites). באמצע שנות ה-80 זוהו על ידי Jeffreys וחב' רצפים בהם האורך של כל יחידה נשנית הוא קצר יותר מהסטליטים (כ-15 נוקליאודיטים בלבד) ועל כן כינויים הוא מיניסטליטים (minisatellities). מעקובות דנ"א אלה חוזרות על עצמן מספר רב של פעמים באתרים שונים בגנום. קבוצת חוקרים זו מצאה, שמספר החזרות של רצף הבסיסים (נוקליאוטידים) באתר מסוים של מיניסטליט שונה בין פרט לפרט. באמצעות שיטות מולקולתיות הם הראו, שניתן לקבל דגם פסים דמוי "ברקוד" שהוא ייחודי לכל אדם, וכך נקבע המונח טביעות האצבעות של הדנ"א (DNA fingerprints).

מוחמד מחאג'נה, שרון צימרמן-אביצרור, רפאל וייץ

היח' לנירולוגיה של הילד, מרכז שניידר לרפואת ילדים, פתח תקווה

נירופיברומטוזיס סוג 1 (נ"פ-1)* היא אחת המחלות השכיחות על רקע הפרעה בגן יחיד. שכיחות המחלה לפי עבודות שונות נעה בין 1/3,000-1/4,000. התורשה של מחלה זו, היא אוטוסומית שולטנית, אך שכיחות המוטאציות החדשות מגיעה עד ל-50% מהמקרים.

Prevalence of APOE 4 Allele in Israeli Ethnic Groups

O. Hilkevich, J. Chapman, B-S. Bone, A.D. Korczyn

Neurology Dept., Tel Aviv Medical Center, and Depts. of Physiology, Pharmacology and Human Genetics, Sackler Faculty of Medicine, Tel Aviv University

The 4 allele of the APOE gene, coding for apo-lipoprotein E, is the most common genetic risk factor for Alzheimer's disease and a significant risk factor for coronary atherosclerosis. There is therefore much interest in studying its frequency in different ethnic groups.

We examined its frequency in Jews originating from Libya, Buchara and Ethiopia and in Jews of Sepharadi and Ashkenazi origins. Its frequency among Ethiopian immigrants was 0.27, significantly higher than in the other groups, in which the frequency was between 0.067 and 0.10. These differences in allele frequency may serve as a basis for future studies in Israel to assess the relative contributions of genetic and environmental factors to the incidence of dementia.

Muir-Torre Syndrome: Importance of Clinical Diagnosis and Genetic Investigation

Hana Strul, Paul Rozen, Tova Naiman, Ruth Shomrat

Gastroenterology Dept. and Genetics Institute, Tel Aviv Medical Center and Tel Aviv University

Muir-Torre syndrome is a relatively rare cutaneous manifestation of hereditary nonpolypous colorectal cancer (HNPCC). This autosomal dominant syndrome is characterized by a combination of sebaceous gland and malignant visceral tumors. The common sites of internal malignancies are the gastrointestinal tract and urinary system. It appears in early adult life and its clinical course is relatively slow.

In some families genetic diagnosis can identify asymptomatic carriers of the mutation. All first-degree relatives, especially mutation carriers, should be referred from the age of 20 years for routine follow-up and early treatment, as it has been proven to decrease morbidity and mortality.

We present a 51-year-old man with Muir-Torre syndrome diagnosed by the presence of multiple adenomas of sebaceous glands, colonic adenoma and adenocarcinoma of the duodenum. The family history was typical for HNPCC. A mutation in the hMSH2 gene on chromosome 2p was found in the patient and in several asymptomatic family members. The aim of this report is to increase awareness of this syndrome and emphasize the importance of referring patients and their families for clinical and genetic counseling and diagnosis.

Oncogenetic Counseling and Genetic Testing of Those at High Risk for Breast and Ovarian Cancer

Livia Theodor, Ronit Shiri-Sverdlov, Galit Hirsch Yechezkel, Revital Bruchim Bar-Sade, Eva Gak, Irit Friedman, Anna Kruglikova, Gilad Ben-Baruch, Shulamit Risel, Moshe Z. Papa, Boleslav Goldman, Eitan Friedman

Oncogenetics Unit, Dept. of Clinical Epidemiology, Institute of Genetics, and Gynecology, Oncology, and Surgical Depts., Chaim Sheba Medical Center, Tel Hashomer

There is inherited predisposition to breast and ovarian cancer in 5-10% of all women with these diseases. Germline mutations in BRCA1 and BRCA2 presumably account for most of the genetically susceptible individuals. We summarize 2 years of experience in counseling and testing for inherited predisposition to these cancers.

597 women (from 320 families) have been evaluated since August 1995. 242 were evaluated for inherited predisposition to breast and ovarian cancer. One-third had clear-cut evidence of familial background. 74 families were of Ashkenazi origin; the age range of breast cancer was 30-35, of ovarian cancer 40-45. In 80% of families other cancers were also noted in first degree family members, including lung, colon, and prostate cancer and leukemia.

Genetic testing revealed that 45% of affected and 25% of unaffected women were carriers of a mutation in BRCA1 or BRCA2: 67/90 185delAG (BRCA1), 12/90 6174delT (BRCA2), and 4/90 of 5382insC (BRCA1). In addition, a novel mutation in exon 11 of BRCA1 was detected, carried by 7/90 women. The experience gained in oncogenetic counseling and genetic testing for inherited cancer predisposition will eventually enable determining an optimal, rational therapeutic regimen in carriers of mutations.

Familial Adenomatous Polyposis: Establishing a Registry and Genetic and Molecular Analysis

R. Shomrat, R. Bruchim, Y. Galanty, Z. Samuel, C. Legum, M. Rabau, P. Rozen

Genetic Institute and Depts. of Gastroenterology and Surgery, Tel Aviv Medical Center and Sackler Faculty of Medicine, Tel Aviv University

Familial adenomatous polyposis (FAP), a dominantly inherited disease, is caused by a mutation in the adenomatous polyposis coli gene in chromosome 5q21. The gene has 15 exons, a physical length of 10 Kb and an open reading frame of 8.5 Kb. Exon 15 codes 66% of the mRNA and has a mutation cluster region which accounts for over 50% of mutations. The disease usually leads to the appearance of hundreds of adenomatous polyps in the transverse and descending colon between puberty and age 20 years and to colon cancer before the age of 40. Early detection is essential to prevent the development of metastasizing cancer. Since 1994 we have recruited 23 families for genetic counseling. DNA was obtained from 19 unrelated FAP patients and 219 high risk relatives in 19 unrelated families following confirmation of the diagnosis. In addition to linkage studies, direct mutational analysis was performed using the protein truncation test for most of exon 15 and single strand conformation polymorphism analysis for the other exons. These exons account for most of the mutations identified to date. Of 19 unrelated probands, 14 had detectable mutations. Exon 15 accounted for 6 families, exons 5, 7 and 14 for 1 each, exon 9 for 3, and exon 8 for 2. Combined mutational and linkage analysis identified 18 presymptomatic carriers who received genetic and clinical counseling. Our FAP patients did not differ significantly from those of larger studies in other countries with regard to the distribution of the mutations, gender and genotype-phenotype correlation, or ethnic distribution.