Screening of patients at risk for 22q11 deletion.

UNLABELLED: The aim of this study was to determine whether deletion 22q11.2 studies should become apart of a standardized diagnostic workup for selected groups of at risk patients. We prospectively investigated four cohorts of unselected patients referred because of 1) congenital heart defect (CHD), 2) palatal anomalies, 3) hypocalcaemia, 4) dysmorphic features suggestive of del 22q11.2. Fluorescence in situ hybridization analysis revealed deletion 22q11.2 in 9.4% (6/64) patients with CHD. From 18 patients referred because of the hypocalcaemia, six (33.3%) had 22q11.2 deletion. In the group of 31 children with dysmorphic traits, the diagnosis was confirmed in two (6.4%) patients. None of the 58 children with palatal anomalies showed evidence of 22q11.2 deletion. CONCLUSIONS: Testing for the 22q11.2 microdeletion can be recommended in all patients with conotruncal heart defects and in patients with hypocalcaemia. It should be also considered in patients presenting only with dysmorphic traits suggestive of del 22q11.2, while screening in patients with cleft palate is not warranted.

Premature chromatid separation in a woman with carcinoma in situ of the uterine cervix and in her son with keratoacanthoma.

An increased frequency of cells with premature chromatid separation (PCS) involving most chromosomes of a metaphase was observed in blood cultures of both a woman and her son with tumor. The mother had carcinoma in situ of the cervix, diagnosed at age of 42 years, and her son had keratoacanthoma, diagnosed at age of 23 years. To our knowledge, these are the first reported cases of carcinoma in situ of the uterine cervix and keratoacanthoma in patients with PCS. These findings provide additional evidence for a possible association of PCS and predisposition to malignancies.

[Evaluation of genetic causes of mental retardation]. / Evaluacija genetickih uzroka mentalne retardacije.

Causes of mental retardation that affects 1-2% of general population are numerous and heterogeneous and include genetic and environmental factors. Improvement of diagnostic techniques and progress made in mapping genes associated with specific mental retardation syndromes provide the possibility to make precise diagnosis in a proportion of mentally retarded individuals. The present study reviews the current diagnostic possibilities, highlights the problems involved in the diagnosis of mental retardation, providing practical guidelines for rational diagnostic approach and work up in individuals with mental retardation. Diagnosis is highly dependent on a detailed and comprehensive family and personal history, careful physical examination and long-term follow up of the children with developmental delay. Referral to specialised genetic units, where extensive evaluation based on rational selection of the specific investigations is possible, yields best diagnostic results.

Chromosomal aberrations in peripheral blood lymphocytes in patients with newly diagnosed celiac and Crohn's disease.

OBJECTIVES: The aims of this research were to determine the number of chromosomal aberrations in peripheral blood lymphocytes and to evaluate the number of circulating lymphocytes with CD103, integrin expressed on intraepithelial lymphocytes and preserved in enteropathy-associated T-cell lymphoma, in patients with newly diagnosed Crohn's disease, celiac disease, and healthy controls. METHODS: During the period of 30 months, we included 44 patients. Chromosome aberrations were analyzed in peripheral blood lymphocytes by a single cytogeneticist. Multicolor flow cytometric was used for immunophenotyping of peripheral blood lymphocytes. RESULTS: We found a significantly higher number of chromosomal aberrations/100 metaphases in the celiac and Crohn's disease group compared with the controls (P=0.01) and they also had a significantly higher number of aberrant cells compared with the controls (P<0.001). There was no statistically significant difference between the groups with respect to the percentage of CD103+ and CD8+CD103+ cells between groups (P=0.16 and 0.41, respectively) and no correlation between the total number of chromosomal aberrations and the percentage of CD103+ and CD8+CD103+ cells (P=0.06 and 0.06, respectively). CONCLUSION: Patients with active celiac and newly diagnosed Crohn's disease, before treatment initiation, have a significantly increased number of chromosomal aberrations in peripheral blood lymphocytes. No dissemination of intraepithelial cells in the blood and correlation to the chromosomal aberration was found.

Cytogenetic evaluation, fluorescence in situ hybridization, and molecular study of psu idic(X)(pter-->q22.3::q22.3-->pter) chromosome abberation in a girl with moderate growth retardation.

Combined cytogenetic, fluorescence in situ hybridization (FISH), and molecular analysis are useful in the diagnosis of sex chromosome aberrations. These methods were used in karyotype analysis of a 4-year-old girl with mild dysmorphism and growth retardation. Standard cytogenetic and FISH analysis was done on slides obtained from peripheral blood lymphocyte culture, and the molecular study was performed by using DNA polymorphism analysis. Both parents had normal karyotypes. Chromosome analysis of the proband identified the karyotype with 46 chromosomes and a late replicating dicentric X. Interphase FISH with an alpha satellite X centromere probe revealed two mosaic cell lines. Three signals were observed at 84.5% and one signal at 15.5% of the interphase cells. Molecular analysis showed that the dicentric X chromosome was of paternal origin. Based on this study, we concluded that the karyotype of the patient was 45,X/46,X, psu idic(X)(q22.3), with the trisomy Xpter-->q22.3 and monosomy Xqter-->q22.3. Dicentric X was the result of an isolocal break in both chromatids of the paternal X chromosome and subsequent rejoining of the broken ends, followed by the inactivation of one centromere. This study illustrates the usefulness of combined cytogenetic and molecular investigations for the detection of mosaicism, understanding the mechanism of the formation and parental origin of chromosomal rearrangement, and establishing the diagnosis.

Gluten-free diet has a beneficial effect on chromosome instability in lymphocytes of children with coeliac disease.

OBJECTIVES: Children with coeliac disease (CD) have an increased number of chromosome aberrations in peripheral blood lymphocytes. Whether genetically determined or a secondary phenomenon in CD, chromosome abnormalities may be involved in the predisposition to cancer in CD patients. The aim of the study was to follow a group of children with CD in whom the initial frequency of chromosome aberrations at diagnosis was known and to measure the same variable after a minimum of 2 years on a gluten-free diet. METHODS: Chromosome aberrations in peripheral blood lymphocytes were determined in 17 patients with CD, before and after at least 24 months of a gluten free diet (mean, 33 months), and in 15 healthy children. The differences in the frequency of aberrations were analyzed by Mann-Whitney U test and Wilcoxon matched-pairs signed-ranks test. RESULTS: Twelve patients adhered to the diet and had a significantly lower frequency of chromosome aberrations than did 5 patients not following the diet (0.16% v 1.2%; P = 0.03), whereas at presentation there had been no difference (1.54% v 1.2%; P = 0.09). The frequency of aberrations at follow-up in patients who were diet adherent was significantly lower than at presentation (1.54% v 0.16%; P = 0.02) and remained unchanged in patients who were not diet adherent (1.2% v 1.2%; P = 1). After at least 24 months of a gluten-free diet, children with CD did not differ from healthy control subjects (0.16% v 0.27%; P = 0.54), whereas children not following the diet had an increased frequency of aberrations (1.2% v 0.27%; P = 0.05). CONCLUSIONS: The frequency of chromosome aberrations in peripheral blood lymphocytes of patients with CD decreased significantly on a gluten-free diet. We conclude that genomic instability is a secondary phenomenon, possibly caused by chronic intestinal inflammation.

Paternal origin of der(X)t(X;6) in a girl with trisomy 6p and unbalanced t(6;10) mosaicism in her mother.

We present a case of trisomy for the whole short arm of chromosome 6 in a 3-year-old girl with moderate mental retardation, mild facial dysmorphism, short stature, failure to thrive, and no abnormalities of the visceral organs. Cytogenetic and fluorescence in situ hybridization (FISH) analysis revealed a 46, X, der(X)t(X;6)(q22; p11.1) karyotype. The derived X was late replicating with variable spreading of X chromosome inactivation onto the translocated 6p. A normal karyotype was observed in the father, while the mother presented 46,XX/46,XX, der(10)t(6;10)(p11;p11). The mother is a mosaic with unbalanced t(6;10) in 4.7% of cells. To the best of our knowledge, this unusual mosaicism has not yet been reported. In this family the short arm of chromosome 6 was involved in an unbalanced rearrangement with chromosome X in the proband and with chromosome 10 in the mother. In order to study the mechanism of the formation of t(X;6) in the girl we performed DNA polymorphism analysis. These investigations revealed that chromosomes X and 6 involved in the rearrangement are of paternal origin. Our patient exhibits only discrete facial features characteristic of partial trisomy 6p. We suggest that mild phenotypic expression be probably due to X chromosome inactivation spreading onto the translocated 6p. This report show that combined cytogenetic, FISH, and molecular analysis of chromosomal aberrations are necessary for the understanding of the mechanism of formation, parental origin, and genetic counseling.