Vera Ayres Meloni

Prenatal exposure to misoprostol and vascular disruption defects: A case-control study

Prenatal exposure to misoprostol has been associated with Moebius and limb defects. Vascular disruption has been proposed as the mechanism for these teratogenic effects. The present study is a multicenter, case-control study that was designed to compare the frequency of prenatal misoprostol use between mothers of Brazilian children diagnosed with vascular disruption defects and matched control mothers of children diagnosed with other types of defects. A total of 93 cases and 279 controls were recruited in eight participating centers. Prenatal exposure was identified in 32 infants diagnosed with vascular disruption defects (34.4%) compared with only 12 (4.3%) in the control group (P<0.0000001). Our data suggest that prenatal exposure to misoprostol is associated to the occurrence of vascular disruption defects in the newborns.

Mechanisms of ring chromosome formation, ring instability and clinical consequences.

BackgroundThe breakpoints and mechanisms of ring chromosome formation were studied and mapped in 14 patients.MethodsSeveral techniques were performed such as genome-wide array, MLPA (Multiplex Ligation-Dependent Probe Amplification) and FISH (Fluorescent in situ Hybridization).ResultsThe ring chromosomes of patients I to XIV were determined to be, respectively: r(3)(p26.1q29), r(4)(p16.3q35.2), r(10)(p15.3q26.2), r(10)(p15.3q26.13), r(13)(p13q31.1), r(13)(p13q34), r(14)(p13q32.33), r(15)(p13q26.2), r(18)(p11.32q22.2), r(18)(p11.32q21.33), r(18)(p11.21q23), r(22)(p13q13.33), r(22)(p13q13.2), and r(22)(p13q13.2). These rings were found to have been formed by different mechanisms, such as: breaks in both chromosome arms followed by end-to-end reunion (patients IV, VIII, IX, XI, XIII and XIV); a break in one chromosome arm followed by fusion with the subtelomeric region of the other (patients I and II); a break in one chromosome arm followed by fusion with the opposite telomeric region (patients III and X); fusion of two subtelomeric regions (patient VII); and telomere-telomere fusion (patient XII). Thus, the r(14) and one r(22) can be considered complete rings, since there was no loss of relevant genetic material. Two patients (V and VI) with r(13) showed duplication along with terminal deletion of 13q, one of them proved to be inverted, a mechanism known as inv-dup-del. Ring instability was detected by ring loss and secondary aberrations in all but three patients, who presented stable ring chromosomes (II, XIII and XIV).ConclusionsWe concluded that the clinical phenotype of patients with ring chromosomes may be related with different factors, including gene haploinsufficiency, gene duplications and ring instability. Epigenetic factors due to the circular architecture of ring chromosomes must also be considered, since even complete ring chromosomes can result in phenotypic alterations, as observed in our patients with complete r(14) and r(22).

Cytogenetic and molecular evaluation and 20-year follow-up of a patient with ring chromosome 14†

We present a 20‐year follow‐up on a patient with a ring chromosome 14. The ring chromosome was studied by fluorescence in‐situ hybridization (FISH), multiplex‐ligation probe amplification (MLPA), and genome wide SNP array, and no deletions of chromosome 14 were detected, although the telomeric repeat sequence was absent from the ring chromosome. The patient had skeletal abnormalities, and susceptibility to infections, as well as seizures and retinal pigmentation, which are commonly found in individuals with a ring 14. Our patient corroborates the idea that even when no genes are lost during ring formation, a complete ring chromosome can produce phenotypic alterations, which presumably result from ring instability or gene silencing due to the new chromosomal architecture.

X-linked intellectual disability related genes disrupted by balanced X-autosome translocations

Detailed molecular characterization of chromosomal rearrangements involving X‐chromosome has been a key strategy in identifying X‐linked intellectual disability‐causing genes. We fine‐mapped the breakpoints in four women with balanced X‐autosome translocations and variable phenotypes, in order to investigate the corresponding genetic contribution to intellectual disability. We addressed the impact of the gene interruptions in transcription and discussed the consequences of their functional impairment in neurodevelopment. Three patients presented with cognitive impairment, reinforcing the association between the disrupted genes (TSPAN7—MRX58, KIAA2022—MRX98, and IL1RAPL1—MRX21/34) and intellectual disability. While gene expression analysis showed absence of TSPAN7 and KIAA2022 expression in the patients, the unexpected expression of IL1RAPL1 suggested a fusion transcript ZNF611‐IL1RAPL1 under the control of the ZNF611 promoter, gene disrupted at the autosomal breakpoint. The X‐chromosomal breakpoint definition in the fourth patient, a woman with normal intellectual abilities, revealed disruption of the ZDHHC15 gene (MRX91). The expression assays did not detect ZDHHC15 gene expression in the patient, thus questioning its involvement in intellectual disability. Revealing the disruption of an X‐linked intellectual disability‐related gene in patients with balanced X‐autosome translocation is a useful tool for a better characterization of critical genes in neurodevelopment.

Genetic mechanisms leading to primary amenorrhea in balanced X-autosome translocations

OBJECTIVE To map the X-chromosome and autosome breakpoints in women with balanced X-autosome translocations and primary amenorrhea, searching candidate genomic loci for female infertility. DESIGN Retrospective and case-control study. SETTING University-based research laboratory. PATIENT(S) Three women with balanced X-autosome translocation and primary amenorrhea. INTERVENTION(S) Conventional cytogenetic methods, genomic array, array painting, fluorescence in situ hybridization, and quantitative reverse transcription-polymerase chain reaction. MAIN OUTCOME MEASURE(S) Karyotype, copy number variation, breakpoint mapping, and gene expression levels. RESULT(S) All patients presented with breakpoints in the Xq13q21 region. In two patients, the X-chromosome breakpoint disrupted coding sequences (KIAA2022 and ZDHHC15 genes). Although both gene disruptions caused absence of transcription in peripheral blood, there is no evidence that supports the involvement of these genes with ovarian function. The ZDHHC15 gene belongs to a conserved syntenic region that encompasses the FGF16 gene, which plays a role in female germ line development. The break in the FGF16 syntenic block may have disrupted the interaction between the FGF16 promoter and its cis-regulatory element. In the third patient, although both breakpoints are intergenic, a gene that plays a role in the DAX1 pathway (FHL2 gene) flanks distally the autosome breakpoint. The FHL2 gene may be subject to position effect due to the attachment of an autosome segment in Xq21 region. CONCLUSION(S) The etiology of primary amenorrhea in balanced X-autosome translocation patients may underlie more complex mechanisms than interruption of specific X-linked candidate genes, such as position effect. The fine mapping of the rearrangement breakpoints may be a tool for identifying genetic pathogenic mechanisms for primary amenorrhea.

Position effect modifying gene expression in a patient with ring chromosome 14

The clinical phenotype of patients with ring chromosomes usually reflects the loss of genomic material during ring formation. However, phenotypic alterations can also be found in the presence of complete ring chromosomes, in which the breakage and rejoining in terminal regions of both chromosome arms result in no gene loss. Here, we present a patient with a ring chromosome 14 that lost nothing but the telomeres. Since he and other patients with a similar chromosome abnormality present certain abnormal characteristics, we investigated the gene expression of eight chromosome 14 genes to find out whether the configuration of the ring had changed it, possibly producing some of these clinical features. The expression of these eight genes was studied by quantitative real-time polymerase chain reaction (qPCR) in the patient and in seven controls matched for gender and age. Two of them were found to be downregulated in the patient compared to the controls, indicating that his phenotype might be related to alterations in the expression of genes located in the abnormal chromosome, even when the copy number is normal. Thus, the phenotypic alterations found in the presence of complete ring chromosomes may be related to changes in the chromatin architecture, bringing about a change of expression by position effect. These results may explain some of the characteristics presented by our patient.

19q13.33→qter trisomy in a girl with intellectual impairment and seizures

Rearrangements in chromosome 19 are rare. Among the 35 patients with partial 19q trisomy described, only six have a breakpoint defined by array. The 19q duplication results in a variable phenotype, including dysmorphisms, intellectual disability and seizure. In a female patient, although G-banding at 550 band-resolution was normal, multiplex ligation-dependent probe amplification (MLPA) technique and genomic array showed a 10.6 Mb terminal duplication of chromosome 19q13. Fluorescent in situ hybridization (FISH) revealed that the duplicated region was attached to the short arm of chromosome 21 and silver staining showed four small acrocentrics with nucleolar organization region (NOR) activity, suggesting that the breakpoint in chromosome 21 was at p13. This is the first de novo translocation between 19q13.33 and 21p13 described in liveborn. The chromosome 19 is known to be rich in coding and non-coding regions, and chromosomal rearrangements involving this chromosome are very harmful. Furthermore, the 19q13.33→qter region is dense in pseudogenes and microRNAs, which are potent regulators of gene expression. The trisomic level of this region may contribute to deregulation of global gene expression, and consequently, may lead to abnormal development on the carriers of these rearrangements.

Single-nucleotide polymorphism array-based characterization of ring chromosome 18.

OBJECTIVE To study genotype-phenotype correlation of ring chromosome 18 [r(18)] in 9 patients with 46,XN karyotype. STUDY DESIGN In 9 patients with a de novo 46,XN,r(18) karyotype (7 females, 2 males), we performed high-resolution single-nucleotide polymorphism array analysis (Illumina Human Omni1-QuadV1 array in 6 patients, Affymetrix 6.0 array in 3 patients), investigation of parental origin, and genotype-phenotype correlation. RESULTS No breakpoint was recurrent. Single metaphases with loss of the ring, double rings, or secondarily rearranged rings were found in some cases, but true mosaicism was present in none of these cases. In 3 patients, additional duplications in 18p (of 1.4 Mb, 2 Mb, and 5.8 Mb) were detected. In 1 patient, an additional deletion of 472 kb in Xp22.33, including the SHOX gene, was found. Parental origin of r(18) was maternal in 2 patients and paternal in 4 patients, and formation was most likely meiotic. Karyotype was normal in all investigated parents (n = 15). At birth, mean maternal age was 30 years (n = 9) and mean paternal age was 34.4 years (n = 9). CONCLUSION Genotype-phenotype correlation revealed extensive clinical variability but no characteristic r(18) phenotype. Severity of clinical signs were generally correlated with the size of the deletion. Patients with large deletions in 18p and small deletions in 18q exhibited mainly symptoms related to 18p-, whereas those with large deletions in 18q and small deletions in 18p had symptoms of 18q-.

Cytogenomic delineation and clinical follow‐up of two siblings with an 8.5 Mb 6q24.2‐q25.2 deletion inherited from a paternal insertion

The chromosomal segment 6q24‐q25 comprises a contiguous gene microdeletion syndrome characterized by intrauterine growth retardation, growth delay, intellectual disability, cardiac anomalies, and a dysmorphic facial phenotype. We describe here a 10‐year follow‐up with detailed clinical, neuropsychological, and cytomolecular data of two siblings, male and female, who presented with developmental delay, microcephaly, short stature, characteristic facial dysmorphisms, multiple organ anomalies, and intellectual disability. Microarray analysis showed an 8.5 Mb 6q24.2‐q25.2 interstitial deletion. Fluorescence in situ hybridization analyses confirmed the deletions and identified an insertion of 6q into 8q13 in their father, resulting in a high recurrence risk. This is the first report in sibs with distinct neuropsychological involvement, one of them with stenosis of the descending branch of the aorta.

Cytogenomic characterization of an unexpected 17.6 Mb 9p deletion associated to a 14.8 Mb 20p duplication in a dysmorphic patient with multiple congenital anomalies presenting a normal G-banding karyotype.

We describe a female patient with developmental delay, dysmorphic features and multiple congenital anomalies who presented a normal G-banded karyotype at the 550-band resolution. Array and multiplex-ligation probe amplification (MLPA) techniques identified an unexpected large unbalanced genomic aberration: a 17.6Mb deletion of 9p associated to a 14.8 Mb duplication of 20p. The deleted 9p genes, especially CER1 and FREM1, seem to be more relevant to the phenotype than the duplicated 20p genes. This study also shows the relevance of using molecular techniques to make an accurate diagnosis in patients with dysmorphic features and multiple anomalies suggestive of chromosome aberration, even if on G-banding their karyotype appears to be normal. Fluorescence in situ hybridization (FISH) was necessary to identify a masked balanced translocation in the patients mother, indicating the importance of associating cytogenetic and molecular techniques in clinical genetics, given the implications for patient management and genetic counseling.