Masked complex chromosome rearrangement in a child thought to have del(8qter) as the sole cytogenetic abnormality

Cytogenetic analyses of constitutional diseases have disclosed several chromosomal rearrangements. At the molecular level, these rearrangements often result in the breakage of genes or alteration of genome architecture. Fluorescence in situ hybridization (FISH) and molecular investigations of a patient showing hypotonia and dysmorphic traits revealed a masked complex chromosome abnormality previously detected by G-banding as a simple 8qter deletion. To characterize the genetic rearrangements panels of bacterial artificial chromosomes (BACs) covering 8q24.22-->qter were constructed, and short tandem repeats (STRs) were used to refine the localization of the breakpoints and to assess the parental origin of the defect. Chromosome 8 displayed the breakpoint at 8q24.22 and an unexpected distal breakpoint at 8q24.23 resulting in unbalanced translocation of a small 8q genomic region on the chromosome 16qter. The study of the 16qter region revealed that the 16q subtelomere was retained and the translocated material of distal 8q was juxtaposed. Moreover, molecular analyses showed that part of the translocated 8qter segment on der(16) was partially duplicated, inverted and that the rearrangement arose in the paternal meiosis. These findings emphasize the complexity of some only apparently simple chromosomal rearrangements and suggest a subtelomeric FISH approach to enhance diagnostic care when a cytogenetic terminal deletion is found.

Congenital diaphragmatic hernia in CHARGE syndrome

Congenital diaphragmatic hernia (CDH) has been rarely described in CHARGE syndrome. We report a patient affected by CHARGE syndrome presenting with a right-sided Bochdalek-type diaphragmatic hernia, and collect the pertinent literature. Furthermore, we review the embryogenesis of the diaphragm and the pathogenesis of CDH to highlight if this malformation could be explained by a developmental anomaly of CHARGE. On the basis of our study, we suggest that patients affected by CDH, facial asymmetry and cardiovascular or urogenital malformations, should be actively screened for CHARGE syndrome findings.

Gain-of-function RAF1 mutations cause Noonan and LEOPARD syndromes with hypertrophic cardiomyopathy

Noonan and LEOPARD syndromes are developmental disorders with overlapping features, including cardiac abnormalities, short stature and facial dysmorphia. Increased RAS signaling owing to PTPN11, SOS1 and KRAS mutations causes approximately 60% of Noonan syndrome cases, and PTPN11 mutations cause 90% of LEOPARD syndrome cases. Here, we report that 18 of 231 individuals with Noonan syndrome without known mutations (corresponding to 3% of all affected individuals) and two of six individuals with LEOPARD syndrome without PTPN11 mutations have missense mutations in RAF1, which encodes a serine-threonine kinase that activates MEK1 and MEK2. Most mutations altered a motif flanking Ser259, a residue critical for autoinhibition of RAF1 through 14-3-3 binding. Of 19 subjects with a RAF1 mutation in two hotspots, 18 (or 95%) showed hypertrophic cardiomyopathy (HCM), compared with the 18% prevalence of HCM among individuals with Noonan syndrome in general. Ectopically expressed RAF1 mutants from the two HCM hotspots had increased kinase activity and enhanced ERK activation, whereas non-HCM-associated mutants were kinase impaired. Our findings further implicate increased RAS signaling in pathological cardiomyocyte hypertrophy.

Systemin regulates both systemic and volatile signaling in tomato plants

The prevailing reaction of plants to pest attack is the activation of various defense mechanisms. In tomato, several studies indicate that an 18 amino acid (aa) peptide, called systemin, is a primary signal for the systemic induction of direct resistance against plant-chewing pests, and that the transgenic expression of the prosystemin gene (encoding the 200 aa systemin precursor) activates genes involved in the plant response to herbivores. By using a combination of behavioral, chemical, and gene expression analyses, we report that systemin enhances the production of bioactive volatile compounds, increases plant attractivity towards parasitiod wasps, and activates genes involved in volatile production. Our data imply that systemin is involved in the systemic activation of indirect defense in tomato, and we conclude that a single gene controls the systemic activation of coordinated and associated responses against pests.

Genetic Syndromes and Outcome After Surgical Correction of Tetralogy of Fallot

BACKGROUND

Genetic syndromes occur in 20% of patients with tetralogy of Fallot (TOF). The impact of genetic syndromes on surgical repair of TOF in infancy is still under investigation.

METHODS

This retrospective study reviews the outcome of 306 consecutive patients (median age, 5.1 months) who underwent primary (266) or staged (40) repair of TOF between 1994 and 2004. Total follow-up was 1,188 patient-years (mean, 57 months).

RESULTS

Genetic syndromes were documented in 85 patients (27.8%), including 22q11 deletion (27), trisomy 21 (13), vertebral, anal, cardiac, tracheoesophageal, renal, and limb abnormalities (VACTERL, 12), and others (33). Hypoplastic pulmonary arteries (PA) were more common in syndromic (19/85 = 22.3%) than nonsyndromic TOF (20/221 = 9.04%) (p < 0.001). Primary repair was performed in 82.4% syndromic and 88.7% nonsyndromic TOF (p = not significant [NS]). Ten-year actuarial survival was 94.1 +/- 2.3% in nonsyndromic and 84.3 +/-4.2% in syndromic TOF (p < 0.001). Ten-year survival was 96.3 +/- 3.6% for del22q11, 100% for trisomy 21, 63.6 +/- 14.5% for VACTERL, and 78.5 +/- 7.3% for patients with other syndromes (p = 0.022). Survival in syndromic TOF with normal PA anatomy was 89.6 +/- 4.2% for primary repair and 85.7 +/- 12.8% for staged repair (p = NS); freedom from reoperation after complete repair was 74.4 +/- 6.4% for primary correction and 56.3 +/- 11.9% for staged repair (p = 0.04). Cox proportional hazard identified the presence of genetic syndrome (p = 0.011) and central PA hypoplasia (p = 0.002) as independent predictors of mortality.

CONCLUSIONS

Pulmonary arborization defects and genetic syndromes other than del22q11 or trisomy 21, are associated with worse outcome after correction of TOF. Primary TOF repair in syndromic patients with normal PA anatomy is a valid surgical strategy, with no additional risk for mortality and higher freedom from reintervention.

Pure trisomy 19p syndrome in an infant with an extra ring chromosome

We report a 12-month-old infant evaluated for severe hypotonia, psychomotor retardation, and facial dysmorphisms, including round face, high prominent forehead, downward slanted palpebral fissures, hypertelorism, short nose, chubby cheeks, long philtrum, anteverted lower lip, low-set asymmetric and dysmorphic ears. Karyotype analysis disclosed an extra mosaic ring chromosome, which included the whole 19p arm. Four additional patients with supernumerary ring 19 chromosomes have been reported, but none of them had pure trisomy 19p.

Two high throughput technologies to detect segmental aneuploidies identify new Williams-Beuren syndrome patients with atypical deletions

OBJECTIVE

To develop and compare two new technologies for diagnosing a contiguous gene syndrome, the Williams-Beuren syndrome (WBS).

METHODS

The first proposed method, named paralogous sequence quantification (PSQ), is based on the use of paralogous sequences located on different chromosomes and quantification of specific mismatches present at these loci using pyrosequencing technology. The second exploits quantitative real time polymerase chain reaction (QPCR) to assess the relative quantity of an analysed locus.

RESULTS

A correct and unambiguous diagnosis was obtained for 100% of the analysed samples with either technique (n = 165 and n = 155, respectively). These methods allowed the identification of two patients with atypical deletions in a cohort of 182 WBS patients. Both patients presented with mild facial anomalies, mild mental retardation with impaired visuospatial cognition, supravalvar aortic stenosis, and normal growth indices. These observations are consistent with the involvement of GTF2IRD1 or GTF2I in some of the WBS facial features.

CONCLUSIONS

Both PSQ and QPCR are robust, easy to interpret, and simple to set up. They represent a competitive alternative for the diagnosis of segmental aneuploidies in clinical laboratories. They have advantages over fluorescence in situ hybridisation or microsatellites/SNP genotyping for detecting short segmental aneuploidies as the former is costly and labour intensive while the latter depends on the informativeness of the polymorphisms.

Clinical manifestations of Deletion 22q11.2 syndrome (DiGeorge/Velo-Cardio-Facial syndrome)

Deletion 22q11.2 syndrome (Del22) (DiGeorge/Velo-Cardio-Facial syndrome) is characterized by congenital heart defect (CHD), palatal anomalies, facial dysmorphisms, neonatal hypocalcemia, immune deficit, speech and learning disabilities. CHD is present in 75% of patients with Del22. The most frequently seen cardiac malformations are "conotruncal" defects, including tetralogy of Fallot (TF), pulmonary atresia with ventricular septal defect (PA-VSD), truncus arteriosus (TA), interrupted aortic arch (IAA), and ventricular septal defect (VSD). The study of the specific "cardiac phenotype" in patients with Del22 shows that a particular cardiac anatomy can be identied in these subjects. In addition to CHD, various organ systems can be involved, so that a multidisciplinary approach is needed in the evaluation of patients with Del22.

High frequency of subtelomeric rearrangements in a cohort of 92 patients with severe mental retardation and dysmorphism

About 5-10% of patients with dysmorphisms, severe mental retardation, and normal standard karyotype are affected by subtelomeric chromosome rearrangements. Sequence homology between different chromosomes and variability between homologs make these regions more susceptible to breakage and reunion. We analyzed the telomeric regions of 92 of these patients, selected with strict clinical criteria. Fifteen individuals (16.3%) had subtelomeric rearrangements. Nine had a unique anomaly, which in one case had been inherited from a balanced parent. Six subjects had double segmental imbalances, including three de novo imbalances. This study provides further evidence for the plasticity of subtelomeric regions, which often results in cryptic rearrangements, and recommends stringent criteria for selecting patient candidates to telomere analysis.

Absorption of sugars and amino acids by the epidermis of Aphidius ervi larvae

Aphidius ervi Haliday (Hymenoptera, Braconidae) is an endophagous parasitoid of several aphid species of economic importance, widely used in biological control. The definition of a suitable artificial diet for in vitro mass production of this parasitoid is still an unresolved issue that, to be properly addressed, requires a deeper understanding both of its nutritional needs and of the functional properties of the larval epithelia involved in nutrient absorption. The experimental evidence presented in this paper unequivocally demonstrates that the uptake of sugars and amino acids takes place through the body surface of the larval stages of A. ervi. These nutrients are efficiently absorbed by the larval epidermis, but the transport rate progressively declines over time. The epidermis exhibits a cross-reactivity to antibodies raised against the mammalian facilitative glucose transporter GLUT2 and the sodium cotransporter SGLT1. The analysis of sugar transport sensitivity to specific inhibitors indicates the involvement of GLUT2-like transporters, while a role for SGLT1-like transporters is not supported. The peculiar pathways of nutrient absorption in A. ervi larvae further corroborate the general idea that the pre-imaginal stages of endophagous koinobiont Hymenoptera, like Metazoan parasites, show a high degree of physiological integration with their hosts.

Biased T-cell receptor repertoires in patients with chromosome 22q11.2 deletion syndrome (DiGeorge syndrome/velocardiofacial syndrome)

Chromosome 22q11.2 deletion (del22q11.2) syndrome (DiGeorge syndrome/velocardiofacial syndrome) is a common syndrome typically consisting of congenital heart disease, hypoparathyroidism, developmental delay and immunodeficiency. Although a broad range of immunologic defects have been described in these patients, limited information is currently available on the diversity of the T-cell receptor (TCR) variable beta (BV) chain repertoire. The TCRBV repertoires of nine patients with del22q11.2 syndrome were determined by flow cytometry, fragment size analysis of the third complementarity determining region (CDR3 spectratyping) and sequencing of V(D)J regions. The rate of thymic output and the phenotype and function of peripheral T cells were also studied. Expanded TCRBV families were detected by flow cytometry in both CD4+ and CD8+ T cells. A decreased diversity of TCR repertoires was also demonstrated by CDR3 spectratyping, showing altered CDR3 profiles in the majority of TCRBV families investigated. The oligoclonal nature of abnormal peaks detected by CDR3 spectratyping was confirmed by the sequence analysis of the V(D)J regions. Thymic output, evaluated by measuring TCR rearrangement excision circles (TRECs), was significantly decreased in comparison with age-matched controls. Finally, a significant up-regulation in the percentage, but not in the absolute count, of activated CD4+ T cells (CD95+, CCR5+, HLA-DR+), IFN-gamma - and IL-2-expressing T cells was detected. These findings suggest that the diversity of CD4 and CD8 TCRBV repertoires is decreased in patients with del22q11.2 syndrome, possibly as a result of either impaired thymic function and/or increased T-cell activation.

Spectrum of clinical variability in familial deletion 22q11.2: from full manifestation to extremely mild clinical anomalies

The 22q11.2 deletion (del22q11.2) syndrome is a genetic condition with wide interfamilial and intrafamilial variability in clinical expression. The aim of the present study was to review the prevalence of parental transmission in our series of patients with del22q11.2, and to analyse clinical findings of the affected parents. Parental transmission of del22q11.2 in our series was 17.2% (15/87), with a preferential maternal transmission (10/15). One or more major features of del22q11.2 were found in all deleted parents, but one of the mothers showed extremely mild clinical anomalies. The present data demonstrate that it should be current policy to test both parents of patients with del22q11.2, irrespective of the parental phenotype, in view of the fact that extremely mild clinical features can be detected in parents of deleted patients. This would provide accurate genetic counselling to del22q11.2 families, as relatively asymptomatic parents must be advised of the 50% risk of transmitting the deletion in a subsequent pregnancy. Various genetic and non-genetic factors, including modifier genes at separate loci, mosaicism, unstable mutations, allelic variations at the haploid locus, chance and environmental interaction, can be hypothesized to be involved in variable clinical expression, even in the same family.

Two novel mutations of the human Δ7-sterol reductase (DHCR7) gene in children with Smith–Lemli–Opitz syndrome

We analyzed seven unrelated children with the Smith-Lemli-Opitz syndrome (SLOS) for mutations in the delta7-sterol reductase gene by using SSCP and direct sequencing. We identified two novel mutations (V330M and R363C) in the DHCR7 gene. Reported mutations found in this study were T93M (3/14 alleles), E448K (2/14), and W151X, G244R, P329L, and R446Q (each found in one allele). The so-called common IVS8-1 G --> C was found in three alleles, confirming its relative rarity among Italian SLOS families. By using a scoring system, clinical severity did not seem to correlate with 7DHC levels and type of mutation. Expanding the spectrum of mutations in SLOS, our study does not support direct genotype-phenotype correlation.

Identification of a novel NOG gene mutation (P35S) in an Italian family with symphalangism

Symphalangism (SYM or SYM1) is an autosomal dominant disorder characterized by multiple joint fusions. The disease is caused by mutations of the NOG gene, that maps to chromosome 17q22. So far, only six independent NOG mutations have been identified. We have analysed an Italian family in which father and son had bilateral symphalangism and detected a novel NOG mutation (P35S), originated in the father from a c.914C>T transition. A different mutation in the same codon (P35R) has been previously described. Comparison between different noggin gene hortologs shows that codon 35 is conserved. Therefore, this codon should play an important role in NOG gene function. This is the first mutation described for NOG after the initial report of NOG mutations being causative of SYM.

Complete transposition of the great arteries: patterns of congenital heart disease in familial precurrence

BACKGROUND

Transposition of the great arteries (TGA) is considered to be associated only rarely with genetic syndromes and to have a low risk of precurrence among relatives of affected patients. Because most family studies have involved a relatively small number of patients and evaluated all types of TGA as a single group, we performed a large, prospective study investigating the precurrence of congenital heart disease in families of children with complete, nonsyndromic TGA.

METHODS AND RESULTS

From January 1997 through December 2000, 370 patients with nonsyndromic, complete TGA were consecutively evaluated and enrolled in the study. The occurrence of cardiac and noncardiac anomalies among relatives of the probands was investigated. Relatives with congenital heart disease were found in 37 of 370 families (10%), including 5 of 37 families (13.5%) with more than one affected relative. TGA itself was the most common precurrent malformation: complete TGA occurred in 6 families and congenitally corrected TGA occurred in 5 families. Precurrence risks for congenital heart disease were calculated at 1.8% (8 of 436) for siblings, 0.5% (4 of 740) for parents, 0.5% (16 of 3261) for first cousins, 0.2% (4 of 2101) for uncles/aunts, and 0.06% (1 of 1480) for grandparents.

CONCLUSIONS

The present study shows that TGA is not always sporadic in families. Precurrence of concordant cardiac defects within affected family members supports monogenic or oligogenic inheritance of TGA in certain kindreds. Moreover, the occurrence of complete TGA and congenitally corrected TGA among first-degree relatives in several different families strongly suggests an underlying pathogenetic link between these 2 malformations that has been previously unrecognized.

Ext-mutation analysis in Italian sporadic and hereditary osteochondromas

Osteochondromas represent the largest group of benign tumors of bone. Multiple osteochondromatosis or hereditary multiple exostoses (EXT) is an autosomal dominant inherited disorder characterized by the presence of multiple benign cartilage-capped exostoses. EXT is genetically heterogeneous with at least 3 chromosomal loci: EXT1 (8q24.1), EXT2 (11p11-p13), and EXT3 (19p). In <5% of EXT patients, the inactivation of both copies of EXT alleles (LOH) is associated with malignant transformation. We have analyzed the EXT1 and EXT2 genes in 9 unrelated EXT families and in a patient with a sporadic osteochondroma, all originating from Italy. Four families show an EXT1 mutation, consisting of a small deletion in 3 of them and a small insertion in the 4th. All these mutations lead to premature termination of translation and thus a truncated EXT1 protein. Three families presented EXT2 mutations consisting of nucleotide substitutions leading to alterations of the third intron splice-site, to an amino acid substitution and to a nonsense mutation. All these mutations cosegregate with the disease phenotype. The sporadic osteochondroma patient carried a novel missense mutation in exon 11 of EXT2 gene, leading to an amino acid substitution. Seven of these mutations have never been described before. EXT2 missense mutations were also confirmed by amino acids conservation between human and mouse and by analysis of a healthy control population. In conclusion, our study provide further evidence that loss of function of the EXT1 or EXT2 gene is the main cause of EXT supporting the putative tumor-suppressor function of these genes.

Exercise testing and 24-hour ambulatory blood pressure monitoring in children with Williams syndrome

The aim of the study was to assess workload capacity and blood pressure (BP) response to treadmill exercise and 24-hour BP monitoring in children with Williams syndrome. Seventeen children were examined (8 males and 9 females) whose mean age was 13.8 +/- 3.6 years. Six patients were on antihypertensive therapy. Each patient underwent clinical examination and measurement of BP at rest, during exercise, and during 24-hour monitoring. Two-dimensional echocardiogram and echo-Doppler of renal arteries were performed. The test was stopped for muscular fatigue or reduced cooperation. The patients, when compared to a population of healthy children, had reduced total time of exercise (7.3 +/- 1.9 vs 14.3 +/- 2.6 min, p < 0.001) and, at the same workload, increased heart rate (167 +/- 19 vs 145 +/- 16 beats/min, p < 0.001) and increased maximum systolic BP (146 +/- 27 vs 128 +/- 12 mmHg, p = 0.01). Ambulatory blood pressure measurement values showed higher systolic blood pressure both during daytime and nighttime. Our study confirms that children and adolescents with Williams syndrome are at high risk for hypertension, probably related to the alterations of large arteries. The data relating to the synthesis of elastin may have a direct relationship to the compliance of the arterial system, leading to hypertension.

Coeliac disease in Williams syndrome

BACKGROUND

Coeliac disease (CD) has been reported in several patients affected by chromosomal disorders, including Down syndrome (DS) and Turner syndrome (TS). CD has also been found in sporadic Williams syndrome (WS) patients. In this study, CD was evaluated in a consecutive series of patients with WS, in order to estimate if the prevalence of CD in WS patients is higher than in the general population.

METHODS AND RESULTS

A consecutive series of 63 Italian patients with WS was studied by analysing the dosage of antigliadin antibodies (AGA) IgA and antiendomisium antibodies (AEA). In patients with positive AGA and AEA, small bowel biopsy was performed. The prevalence of CD in our WS population was compared with that estimated in a published series of 17 201 Italian students. Seven WS patients were found to be positive for AGA IgA and AEA. Six of them underwent small bowel biopsy, which invariably disclosed villous atrophy consistent with CD. The prevalence of CD in the present series of WS patients was 9.5% (6/63), compared to 0.54% (1/184) in the Italian students (p<0.001).

CONCLUSION

The present results suggest that the prevalence of CD in WS is higher than in the general population and is comparable to that reported in DS and TS. AGA and AEA screening is recommended in patients with WS.