Phenotypic variability in 49 cases of ESCO2 mutations, including novel missense and codon deletion in the acetyltransferase domain, correlates with ESCO2 expression and establishes the clinical criteria for Roberts syndrome.

BACKGROUND: Roberts syndrome (RBS) and SC phocomelia are caused by mutations in ESCO2, which codes for an acetyltransferase involved in the regulation of sister chromatid cohesion. Of 26 mutations described to date, only one missense mutation has been reported and all others are predicted to be truncating mutations. Genotype-phenotype analysis has been hampered by limited numbers of patients with clinical information available. OBJECTIVE: To provide unpublished clinical data for 31 patients with proven ESCO2 mutations and combine this series with previously reported clinical and mutation data on 18 cases. Methods Genotype-phenotype correlations and functional effects of two novel ESCO2 mutations were analysed. In situ hybridisation on human embryos at Carnegie stages 14, 17 and 21 was performed to study ESCO2 expression during development. RESULTS AND CONCLUSIONS: Using the cohort of 49 patients, the clinical criteria for RBS were delineated to include: growth retardation; symmetric mesomelic shortening of the limbs in which the upper limbs are more commonly and severely affected than the lower limbs; characteristic facies with microcephaly. The severity of malformations of the facies correlates with the severity of limb reduction. The occurrence of corneal opacities may be associated with specific mutations. Two new mutations, both in the ESCO2 acetyltransferase domain, are described and their acetylation effects in vitro demonstrated. In situ hybridisation on human embryos showed ESCO2 expression in the brain, face, limb, kidney and gonads, which corresponds to the structures affected in RBS.

Congenital microgastria and primary ciliary dyskinesia in a newborn with DiGeorge syndrome and 22q11.2 deletion.

BACKGROUND: Congenital microgastria is an uncommon result of impairment of normal foregut development and rotation during early embryology. Only about 50 cases have been reported in the literature, mostly associated with other multiple congenital anomalies. CASE REPORT: The case of a female newborn with multiple abnormalities, including cardiovascular malformation (type I truncus arteriosus communis) with deletion of chromosome 22q11.2, severe immunodeficiency (DiGeorge syndrome), microgastria, and impaired mucociliary function (primary ciliary dyskinesia) is reported. CONCLUSIONS: An association between the deletion of chromosome 22q11.2, microgastria, and impaired mucociliary function has never been observed before. A casual association seems highly unlikely and we can not exclude the possibility of genetic mechanisms that may link those syndromes.

Congenital hypothyroidism in Young-Simpson syndrome.

We describe a patient with the clinical spectrum of Young-Simpson syndrome. This rare genetic disorder is characterized by congenital hypothyroidism, mental retardation and blepharophimosis. Young-Simpson syndrome is, at present, poorly known to endocrinologists and pediatricians, and should be included in the differential diagnosis of congenital hypothyroidism. It is important to underline that the association of congenital hypothyroidism, blepharophimosis and ptosis allows an exact clinical diagnosis, since the majority of other clinical aspects are common to other disorders.

[Epigenetic study of Rett's syndrome as an adequate model for autistic disorders].

Rett's syndrome (RTT) is a severe hereditary disorder of the nervous system. MECP2 gene mutations are considered as a primary cause of the disease. In the present study, we have found MECP2 mutations in 33 (84.6%) out of 39 RTT females. We have also studied X-inactivation patterns in 70 girls with RTT. A frequency of skewed X-inactivation was 37% (26 patients), being significantly higher (p < 0.001) than that in the controls. The investigation of inactivated X chromosome origin revealed that about 33% pairs had preferentially the inactivated maternal X chromosome. An abnormal type of chromosome X inactivation was observed in all RTT females. Thus, we conclude that skewed X-inactivation may be considered as a common feature of RTT. There is unambiguous evidence that epigenetic alterations in RTT are associated with MECP2 mutations. MeCP2 protein also appears to be involved in transcriptional regulation of chromosome X genes. RTT in females without MECP2 mutations is related to the epigenetic alterations. We suggest X chromosome inactivation study in RTT females and their mothers to be informative for investigation of genetic processes in RTT girls, even in case MECP2 mutations have not been found. RTT could be considered as an appropriate model for studying epigenetic abnormalities in relation to autistic spectrum disorders.

[Genotype-phenotype correlations in Rett syndrome: the study of Russian cohort of patients]. / Kliniko-geneticheskie korreliatsii pri sindrome Retta: izuchenie rossiiskoi kogorty bol'nykh.

Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by mutations in methyl-CpG-binding protein 2 gene (MECP2). We carried out a mutations analysis in Russian cohort of patients with RTT. MECP2 mutations were found in 23 of 28 RTT girls and one boy (82%). Thirteen different types of mutations have been identified: 6 nonsense, 5 missense and 2 deletions in MECP2 gene. In typical RTT form, most frequent mutations were R255X (5 cases) and T158M (4 cases). A boy with classical clinical picture of RTT had R270X mutation. Skewed inactivation of chromosome x has been found in 2 of 27 RTT girls with classical RTT form and "forme fruste". The data obtained imply possible correlations between genotype and phenotype in RTT.

Meiotic origin of two ring chromosomes 18 in a girl with developmental delay.

We report on the cytogenetic, fluorescence in situ hybridization (FISH), and molecular results obtained for a patient with a mild and nonspecific pattern of minor anomalies and developmental delay. In the proband's karyotype one chromosome 18 was replaced by a ring chromosome 18 in all metaphases, with deletion of the terminal regions. Furthermore, 56% of the metaphases contained a supernumerary small ring chromosome. Microdissection followed by FISH analysis demonstrated that the small ring chromosome consisted of material from the pericentromeric region of chromosome 18. The karyotype was defined as 46,XX,r(18)(p11.3q23)[88]/47,XX,r(18)(p11.3q23)+r(18)(p11.22q12.2)[112]. Thus, the patient has a deletion at 18pter and at 18qter, and a mosaic partial trisomy of the pericentromeric region of chromosome 18. We undertook molecular analysis using DNA samples of the patient and her parents in order to clarify the origin and possible mode of formation of the chromosome abnormalities. Our results show a paternal origin of the structurally normal chromosome 18 and a maternal origin for both ring chromosomes 18. Interestingly, the smaller ring chromosome did not arise postzygotically from the larger ring, since the two ring chromosomes contain genetic material derived from the two different maternal chromosomes 18. The abnormalities appear to have arisen during a meiotic division, and it could be speculated that both ring chromosomes 18 arose simultaneously due to complex pairing and recombination events. After fertilization, the small ring chromosome was lost in a subset of cells, thus leading to mosaicism.

Spectrum and distribution of MECP2 mutations in 64 Italian Rett syndrome girls: tentative genotype/phenotype correlation.

We report a direct DNA sequencing analysis of the MECP2 gene undertaken on a further 64 Italian patients with Rett syndrome by using a LICOR 4200 Automated Sequencer. All of the girls entering the study had a consistent clinical diagnosis for this disorder. All coding regions and the flanking intronic splice site sequences were amplified as three non-overlapping fragments by using both forward and reverse primers. The results were then compared to the MECP2 reference sequences published in GenBank. Mutations of the MECP2 gene were identified in 64 of 75 (85.33%) unrelated sporadic Rett syndrome girls. Genotype/phenotype correlation studies, in particular in groups of patients with the same mutation, did not offer definitive and interesting data.

Y-chromosomal STR haplotype in Toscany (central Italy).

Here we show the Y-haplotype database consisting in the loci DYS19, DYS388, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385, YCAII and DXYS156Y of 107 males living in Toscany (central Italy).

DHPLC analysis of the MECP2 gene in Italian Rett patients.

Rett Syndrome (RTT) is an X-linked dominant neurodevelopmental disorder, which almost exclusively affects girls, with an estimated prevalence of one in 10,000-15,000 female births. Mutations in the methyl CpG binding protein 2 gene (MECP2) have been identified in roughly 75% of classical Rett girls. The vast majority of Rett cases (99%) are sporadic in origin, and are due to de novo mutations. We collected DNA samples from 50 Italian classical Rett girls, and screened the MECP2 coding region for mutations by denaturing high-performance liquid chromatography (DHPLC) and subsequent direct sequencing. DHPLC is a recently developed method for mutation screening which identifies heteroduplexes formed in DNA samples containing mismatches between wild type and mutant DNA strands, combining high sensitivity, reduced cost per run, and high throughput. In our series, 19 different de novo MECP2 mutations, eight of which were previously unreported, were found in 35 out of 50 Rett girls (70%). Seven recurrent mutations were characterized in a total of 22 unrelated cases. Initial DHPLC screening allowed the identification of 17 out of 19 different mutations (90%); after optimal conditions were established, this figure increased to 100%, with all recurrent MECP2 mutations generating a characteristic chromatographic profile. Detailed clinical data were available for 27 out of 35 mutation carrying Rett girls. Milder disease was detectable in patients carrying nonsense mutation as compared to patients carrying missense mutations, although this difference was not statistically significant (P = 0.077).

Infrared fluorescent automated detection of thirteen short tandem repeat polymorphisms and one gender-determining system of the CODIS core system.

We used an infrared (IR) automated fluorescence monolaser sequencer for the analysis of 13 autosomal short tandem repeat (STR) systems (TPOX, D3S1358, FGA, CSF1PO, D5S818, D7S820, D8S1179, TH01, vWA, D13S317, D16S359, D18S51, D21S11) and the X-Y homologous gene amelogenin system. These two systems represent the core of the combined DNA index systems (CODIS). Four independent multiplex reactions, based on the polymerase chain reaction (PCR) technique and on the direct labeling of the forward primer of every primer pair, with a new molecule (IRDye800), were set up, permitting the exact characterization of the alleles by comparison with ladders of specific sequenced alleles. This is the first report of the whole analysis of the STRs of the CODIS core using an IR automated DNA sequencer. The protocol was used to solve paternity/maternity tests and for population studies. The electrophoretic system also proved useful for the correct typing of those loci differing in size by only 2 bp. A sensibility study demonstrated that the test can detect an average of 10 pg of undegraded human DNA. We also performed a preliminary study analyzing some forensic samples and mixed stains, which suggested the usefulness of using this analytical system for human identification as well as for forensic purposes.

Modified primers for D12S391 and a modified silver staining technique.

In this paper we describe a new primer pair for the short tandem repeat (STR) D12S391 which makes it possible to obtain considerably shorter amplification fragments (125-173 bp), compared to the previously published primers (205-253 bp). The primers were tested on 70 samples with known genotypes, and no differing results were found. In sensitivity studies, forensic casework samples and DNA quality studies, we proved that the new primers can improve the efficiency of the amplification. Moreover, the resolution of this locus on denaturing PAGE followed by silver staining was dramatically improved. This improvement was found to be most valuable for typing the rare.3 variants known for this locus. We also present and propose a new method for silver staining denaturing acrylamide gels.

Premature ovarian failure (POF) and fragile X premutation females: from POF to to fragile X carrier identification, from fragile X carrier diagnosis to POF association data.

Early menopause in the fragile X carriers has been well documented in several reports. All surveys demonstrated that 13-25% of fragile X carriers experienced premature ovarian failure (POF), defined as menopause before the age of 40 years. In 1995 we started screening two groups of subjects as a part of a Fragile X Research Program: 1) women previously diagnosed as fragile X carriers from the register of our center and 2) women with POF and without a family history of fragile X or other forms of mental retardation. In this study we report the preliminary data collected from 75 fragile X families; in 30 of them, POF was present in one or several subjects, all of whom had a fragile X premutation. None of the women with a full mutation experienced POF in our series of patients. We also identified 89 families without a family history of fragile X or mental retardation, and there were 108 subjects who experienced POF, of which 6.5% had a fragile X premutation. This is 70-fold higher than the background prevalence of fragile X premutation in the Italian population and suggests an association with POF. These data confirm the results of other surveys.

Genetic variation at the STR loci D12S391 and CSF1PO in four populations from Austria, Italy, Egypt and Yemen.

The short tandem repeat systems (STRs) D12S391 and CSF1P0 were amplified by the polymerase chain reaction (PCR) on blood samples from 100 to 158 unrelated Austrians, Italians, Yemenians and Egyptians. The samples were analyzed by both native and denaturing electrophoresis and two primer pairs were tested for the CSF1PO locus. Except for the CSF1PO data on the Egyptians, no deviations from the Hardy-Weinberg equilibrium were detected. For D12S391, no significant differences were found between the two Arab populations and between the two European populations, but the differences between both Arab populations and the Italians were significant. For CSF1PO, differences were only observed between the Yemenians and all three other populations. No evidence of linkage disequilibrium between the two STRs was found. The observation of a D12S391 allele consisting of only 14 repeats was confirmed by sequencing.

Deletions in HOXD13 segregate with an identical, novel foot malformation in two unrelated families.

Synpolydactyly (SPD) is a dominantly inherited congenital limb malformation consisting of 3/4 syndactyly in the hands and 4/5 syndactyly in the feet, with digit duplication in the syndactylous web. The condition recently has been found to result from different-sized expansions of an amino-terminal polyalanine tract in HOXD13. We report a novel type of mutation in HOXD13, associated in some cases with features of classic SPD and in all cases with a novel foot phenotype. In two unrelated families, each with a different intragenic deletion in HOXD13, all mutation carriers have a rudimentary extra digit between the first and second metatarsals and often between the fourth and fifth metatarsals as well. This phenotype has not been reported in any mice with genetic modifications of the HoxD gene cluster. The two different deletions affect the first exon and the homeobox, respectively, in each case producing frameshifts followed by a long stretch of novel sequence and a premature stop codon. Although the affected genes may encode proteins that exert a dominant negative or novel effect, they are most likely to act as null alleles. Either possibility has interesting implications for the role of HOXD13 in human autopod development.

Study on the STR TPOX in an Italian and an Austrian population using two different primer pairs and three different electrophoretic methods.

The short tandem repeat TPOX was studied using two different pairs of primers and three different electrophoretic methods with the aim of optimizing and standardizing the typing conditions for this locus. A genetic population study was subsequently conducted on two population samples from Central Italy (151 individuals) and from Austria (153 individuals) and compared using an R x C contingency table. With the aim of using this system for forensic samples, differences in sensitivity between the methods utilized were studied and several parameters of forensic interest for the two populations (PD, MEC, MEP, pM, PIC) were calculated. A new multiplex system for the loci CSF1PO, TPOX and CD4 is also presented.

Detection of a homozygous four base pair deletion in the protein X gene in a case of pyruvate dehydrogenase complex deficiency.

While the presence of a lipoyl-containing protein (protein X) separate from lipoyl transacetylase in the pyruvate dehydrogenase complex (PDC) has been known for some time, until recently only the cDNA for the yeast enzyme has been cloned. We have cloned, sequenced and characterized the cDNA encoding the human protein X and localized the protein X gene to chromosome 11p13. We also report here a new case of protein X deficiency identified immunologically, with decreased activity of PDC and without mutations in the E1alpha subunit or E1beta subunit. We report that the cDNA and gene of this patient for protein X has a homozygous 4 bp deletion, specifically in the putative mitochondrial targeting signal sequence which results in a premature stop codon. This is the first documented case of a molecular defect in pyruvate dehydrogenase protein X.

Synpolydactyly phenotypes correlate with size of expansions in HOXD13 polyalanine tract.

Synpolydactyly (SPD) is a dominantly inherited congenital limb malformation. Typical cases have 3/4 finger and 4/5 toe syndactyly, with a duplicated digit in the syndactylous web, but incomplete penetrance and variable expressivity are common. The condition has recently been shown to be caused by expansions of an imperfect trinucleotide repeat sequence encoding a 15-residue polyalanine tract in HOXD13. We have studied 16 new and 4 previously published SPD families, with between 7 and 14 extra residues in the tract, to analyze the molecular basis for the observed variation in phenotype. Although there is no evidence of change in expansion size within families, even over six generations, there is a highly significant increase in the penetrance and severity of phenotype with increasing expansion size, affecting both hands (P = 0.012) and feet (P < 0. 00005). Affected individuals from a family with a 14-alanine expansion, the largest so far reported, all have a strikingly similar and unusually severe limb phenotype, involving the first digits and distal carpals. Affected males from this family also have hypospadias, not previously described in SPD, but consistent with HOXD13 expression in the developing genital tubercle. The remarkable correlation between phenotype and expansion size suggests that expansion of the tract leads to a specific gain of function in the mutant HOXD13 protein, and has interesting implications for the role of polyalanine tracts in the control of transcription.

Increased mutagen-induced chromosome damage in patients with transformed laryngeal pre-cancerosis.

Factors that contribute to malignant transformation of laryngeal pre-neoplastic lesions remain largely unknown. Potential etiological factors may be related to a genetically controlled sensitivity to environmental carcinogens. In this study, we investigated bleomycin-induced chromosome damage in 15 patients who experienced a malignant transformation of preneoplastic laryngeal lesions during follow-up, as compared with chromosome fragility in 30 historical controls with no progression of keratoses during a 10-year follow-up, in a match-paired analysis. Chromosomal analysis demonstrated higher sensitivity to clastogens in patients with malignant progression of laryngeal pre-neoplastic lesions than that of control patients with no evolution of their original laryngeal keratoses (p = 0.003). Furthermore, among the study patients, chromosome sensitivity was most apparent in non-tobacco users with malignant transformation of laryngeal disease. Our data suggest that subjects with pre-neoplastic laryngeal lesion showing increased susceptibility to carcinogens could be at higher risk for development of laryngeal carcinoma.

Fragile X founder chromosomes in Italy: a few initial events and possible explanation for their heterogeneity.

A total of 137 fragile X and 235 control chromosomes from various regions of Italy were haplotyped by analyzing two neighbouring marker microsatellites, FRAXAC1 and DXS548. The number of CGG repeats at the 5' end of the FMR1 gene was also assessed in 141 control chromosomes and correlated with their haplotypes. Significant linkage disequilibrium between some "major" haplotypes and fragile X was observed, while other "minor" haplotypes may have originated by subsequent mutation at the marker microsatellite loci and/or recombination between them. Recent evidence suggests that the initial mechanism leading to CGG instability might consist of rare (10 (-6/-7)) CGG repeat slippage events and/or loss of a stabilizing AGG via A-to-C transversion. Also, the apparently high variety of fragile X chromosomes may be partly due to the relatively high mutation rate (10 (-4/-5)) of the microsatellite markers used in haplotyping. Our fragile X sample also showed a higher than expected heterozygosity when compared to the control sample and we suggest that this might be explained by the chance occurrence of the few founding events on different chromosomes, irrespective of their actual frequency in the population. Alternatively, a local mechanism could enhance the microsatellite mutation rate only on fragile X chromosomes, or fragile X mutations might occur more frequently on certain background haplotypes.