Disruption of exon-bridging interactions between the minor and major spliceosomes results in alternative splicing around minor introns.

Vertebrate genomes contain major (>99.5%) and minor (<0.5%) introns that are spliced by the major and minor spliceosomes, respectively. Major intron splicing follows the exon-definition model, whereby major spliceosome components first assemble across exons. However, since most genes with minor introns predominately consist of major introns, formation of exon-definition complexes in these genes would require interaction between the major and minor spliceosomes. Here, we report that minor spliceosome protein U11-59K binds to the major spliceosome U2AF complex, thereby supporting a model in which the minor spliceosome interacts with the major spliceosome across an exon to regulate the splicing of minor introns. Inhibition of minor spliceosome snRNAs and U11-59K disrupted exon-bridging interactions, leading to exon skipping by the major spliceosome. The resulting aberrant isoforms contained a premature stop codon, yet were not subjected to nonsense-mediated decay, but rather bound to polysomes. Importantly, we detected elevated levels of these alternatively spliced transcripts in individuals with minor spliceosome-related diseases such as Roifman syndrome, Lowry-Wood syndrome and early-onset cerebellar ataxia. In all, we report that the minor spliceosome informs splicing by the major spliceosome through exon-definition interactions and show that minor spliceosome inhibition results in aberrant alternative splicing in disease.

Pathogenic variants in EP300 and ANKRD11 in patients with phenotypes overlapping Cornelia de Lange syndrome.

Cornelia de Lange syndrome (CdLS), Rubinstein-Taybi syndrome (RSTS), and KBG syndrome are three distinct developmental human disorders. Variants in seven genes belonging to the cohesin pathway, NIPBL, SMC1A, SMC3, HDAC8, RAD21, ANKRD11, and BRD4, were identified in about 80% of patients with CdLS, suggesting that additional causative genes remain to be discovered. Two genes, CREBBP and EP300, have been associated with RSTS, whereas KBG results from variants in ANKRD11. By exome sequencing, a genetic cause was elucidated in two patients with clinical diagnosis of CdLS but without variants in known CdLS genes. In particular, genetic variants in EP300 and ANKRD11 were identified in the two patients with CdLS. EP300 and ANKRD11 pathogenic variants caused the reduction of the respective proteins suggesting that their low levels contribute to CdLS-like phenotype. These findings highlight the clinical overlap between CdLS, RSTS, and KBG and support the notion that these rare disorders are linked to abnormal chromatin remodeling, which in turn affects the transcriptional machinery.

Lowry-Wood syndrome: further evidence of association with RNU4ATAC, and correlation between genotype and phenotype.

Lowry-Wood syndrome (LWS) is a skeletal dysplasia characterized by multiple epiphyseal dysplasia associated with microcephaly, developmental delay and intellectual disability, and eye involvement. Pathogenic variants in RNU4ATAC, an RNA of the minor spliceosome important for the excision of U12-dependent introns, have been recently associated with LWS. This gene had previously also been associated with microcephalic osteodysplastic primordial dwarfism (MOPD) and Roifman syndrome (RS), two distinct conditions which share with LWS some skeletal and neurological anomalies. We performed exome sequencing in two individuals with Lowry-Wood syndrome. We report RNU4ATAC pathogenic variants in two further patients. Moreover, an analysis of all RNU4ATAC variants reported so far showed that FitCons scores for nucleotides mutated in the more severe MOPD are higher than RS or LWS and that they were more frequently located in the 5' Stem-Loop of the RNA critical for the formation of the U4/U6.U5 tri-snRNP complex, whereas the variants are more dispersed in the other conditions. We are thus confirming that RNU4ATAC is the gene responsible for LWS and provide a genotype-phenotype correlation analysis.

FAM111A mutations result in hypoparathyroidism and impaired skeletal development.

Kenny-Caffey syndrome (KCS) and the similar but more severe osteocraniostenosis (OCS) are genetic conditions characterized by impaired skeletal development with small and dense bones, short stature, and primary hypoparathyroidism with hypocalcemia. We studied five individuals with KCS and five with OCS and found that all of them had heterozygous mutations in FAM111A. One mutation was identified in four unrelated individuals with KCS, and another one was identified in two unrelated individuals with OCS; all occurred de novo. Thus, OCS and KCS are allelic disorders of different severity. FAM111A codes for a 611 amino acid protein with homology to trypsin-like peptidases. Although FAM111A has been found to bind to the large T-antigen of SV40 and restrict viral replication, its native function is unknown. Molecular modeling of FAM111A shows that residues affected by KCS and OCS mutations do not map close to the active site but are clustered on a segment of the protein and are at, or close to, its outer surface, suggesting that the pathogenesis involves the interaction with as yet unidentified partner proteins rather than impaired catalysis. FAM111A appears to be crucial to a pathway that governs parathyroid hormone production, calcium homeostasis, and skeletal development and growth.

Characterization of 14 novel deletions underlying Rubinstein-Taybi syndrome: an update of the CREBBP deletion repertoire.

Rubinstein-Taybi syndrome (RSTS) is a rare, clinically heterogeneous disorder characterized by cognitive impairment and several multiple congenital anomalies. The syndrome is caused by almost private point mutations in the CREBBP (~55% of cases) and EP300 (~8%) genes. The CREBBP mutational spectrum is variegated and characterized by point mutations (30-50 %) and deletions (~10%). The latter are diverse in size and genomic position and remove either the whole CREBBP gene and its flanking regions or only an intragenic portion. Here, we report 14 novel CREBBP deletions ranging from single exons to the whole gene and flanking regions which were identified by applying complementary cytomolecular techniques: fluorescence in situ hybridization, multiplex ligation-dependent probe amplification and array comparative genome hybridization, to a large cohort of RSTS patients. Deletions involving CREBBP account for 23% of our detected CREBBP mutations, making an important contribution to the mutational spectrum. Genotype-phenotype correlations revealed that patients with CREBBP deletions extending beyond this gene did not always have a more severe phenotype than patients harboring CREBBP point mutations, suggesting that neighboring genes play only a limited role in the etiopathogenesis of CREBBP-centerd contiguous gene syndrome. Accordingly, the extent of the deletion is not predictive of the severity of the clinical phenotype.

Recessive bullous dermolysis of the newborn in preterm siblings with a missense mutation in type VII collagen.

Bullous dermolysis of the newborn is a dominant or recessive inherited subtype of dystrophic epidermolysis bullosa characterized by the tendency to spontaneously stop blistering within the first months of life. Here we report two siblings with bullous dermolysis of the newborn who were born prematurely and have a novel recessive mutation, p.Pro2259Leu, in the triple helix domain of type VII collagen. We discuss the possible relationship between genotype and prematurity and clinical manifestations in these patients.

Unilateral ectopic parotid gland in CHARGE syndrome.

Unilateral absence of a parotid gland at the expected location is an extremely rare condition with only a few cases reported in the medical literature and, to our knowledge, never previously described in association with CHARGE syndrome (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities and deafness). Although this entity is usually associated with a complex constellation of anomalies, additional findings have been described, including cranial nerve dysfunction (VII, VIII, IX and X). We present a case that illustrates the association of CHARGE syndrome with absence of parotid gland at normal location with ectopic parotid tissue lateral to masseter muscle, incidentally detected on brain MRI and subsequently confirmed on neck MRI.

Are there any strategies to improve neonatal outcomes associated with epidural analgesia in labor?

BACKGROUND AND AIM OF THE WORK: This study was aimed at evaluating the relationship between epidural analgesia and perinatal outcomes and at verifying the advisability of procedural changes in assistance to labor. SUBJECTS AND METHODS: From January to December 2012, we conducted a retrospective case-control study on 1,963 laboring pregnant women admitted to the Parma University Hospital. We considered two groups: Group 1 received epidural analgesia and Group 2 received no analgesia. Women with elective cesarean sections, multiple pregnancies or deliveries at <34 weeks were excluded. We recorded maternal data (age, type of delivery, obstetric procedures, premature rupture of membranes, screenings for Group-B Streptococcus) and neonatal data (birth weight, gestational age, 1- and 5-minute Apgar scores, diagnosis at discharge). RESULTS: Of the 1,963 laboring women, 287 requested analgesia and 1,676 did not. We found no significant differences between the two groups in the rates of cesarean section, clavicle fracture, and 1-minute Apgar score between 4 and 7. By contrast, we observed a higher rate of instrumental deliveries (p<0.01), fetal occiput posterior position (p<0.05), neonatal cephalohematoma (p=0.01) in Group 1 than in Group 2 . In Group 1 we also found a higher number of newborns with 1-minute Apgar score of 3 or less (p=0.016). In addition, a significantly higher number of women in Group 1 had fever during labor (p=0.003, odds ratio 5.01). CONCLUSIONS: Our results suggest that strategies should be activated to overcome or limit the side-effects of analgesia in labor through prospective and multidisciplinary studies. 

SMC1A codon 496 mutations affect the cellular response to genotoxic treatments.

Cornelia de Lange syndrome is a pleiotropic developmental syndrome characterized by growth and cognitive impairment, facial dysmorphic features, limb anomalies, and other malformations. Mutations in core cohesin genes SMC1A and SMC3, and the cohesin regulatory gene, NIPBL, have been identified in Cornelia de Lange syndrome probands. Patients with NIPBL mutations have more severe phenotypes when compared to those with mutations in SMC1A or SMC3. To date, 26 distinct SMC1A mutations have been identified in patients with Cornelia de Lange syndrome. Here, we describe a 3-year-old girl with psychomotor and cognitive impairment, mild facial dysmorphic features but no limb anomaly, heterozygous for a c.1487G>A mutation in SMC1A which predicts p.Arg496His. We show that this mutation leads to an impairment of the cellular response to genotoxic treatments.

Molecular Polymorphisms of Vascular Endothelial Growth Factor Gene and Bronchopulmonary Dysplasia in Very Low Birth Weight Infants.

Background: Bronchopulmonary dysplasia (BPD) is a chronic lung disease affecting primarily preterm and very low birth weight (VLBW) infants. Despite the advances in perinatal care, BPD remains a major clinical and costly complication in premature infants. The pathogenesis of BPD is complex and multifactorial. Prematurity, mechanical ventilation, oxidative stress, and inflammation are recognized as major interrelated contributing factors. Recently, some candidate genes involved in angiogenesis and alveolarization regulating mechanisms have been associated to BPD risk development. The aim of this study was to evaluate the role of vascular endothelial growth factor (VEGF) polymorphisms on BPD onset in VLBW newborns. Methods: Eighty-two VLBW infants, without major anomalies, were consecutively enrolled: 33 developed BPD (BPD group) and 49 infants without BPD served as controls (control group). In all infants, two polymorphisms, respectively (VEGF receptor) VEGFR1-710 C/T and VEGF +936 C/T, were determined through salivary brush. Genomic DNA was extracted and purified from saliva samples by using the MasterAmp Buccal Swab DNA Extraction Kit (Tebu-bio, Milan, Italy). Results: Significant statistic differences were found between BPD newborns and controls with regard to gestational age, birth weight, mechanical ventilation, duration of oxygen therapy, maternal preeclampsia, and chorioamnionitis. No differences were detected between genotypic and allelic levels regarding VEGFR1 and VEGF molecular polymorphisms. Conclusions: Two single nucleotide polymorphisms within VEGF and VEGFR1 genes are not associated with BPD. Further researches are needed to reveal gene polymorphisms involved in vascular development as contributors to the onset of BPD.

The Pitt-Hopkins syndrome: report of 16 new patients and clinical diagnostic criteria.

Pitt-Hopkins syndrome (PTHS) is characterized by severe intellectual disability, typical facial gestalt and additional features, such as breathing anomalies. Following the discovery of the causative haploinsufficiency of transcription factor 4 (TCF4), about 60 patients have been reported. We looked for TCF4 mutations in 63 patients with a suspected PTHS. Haploinsufficiency of TCF4 was identified in 14 patients, as a consequence of large 18q21.2 chromosome deletions involving TCF4 (2 patients), gene mutations (11 patients) and a t(14q;18q) balanced translocation disrupting TCF4 (one patient). By evaluating the clinical features of these patients, along with literature data, we noticed that, in addition to the typical facial gestalt, the PTHS phenotype results from the various combinations of the following characteristics: intellectual disability with severe speech impairment, normal growth parameters at birth, postnatal microcephaly, breathing anomalies, motor incoordination, ocular anomalies, constipation, seizures, typical behavior and subtle brain abnormalities. Although PTHS is currently considered to be involved in differential diagnosis with Angelman and Rett syndromes, we found that combining the facial characteristics with a detailed analysis of both the physical and the neurological phenotype, made molecular testing for PTHS the first choice. Based on striking clinical criteria, a diagnosis of PTHS was made clinically in two patients who had normal TCF4. This report deals with the first series of PTHS patients of Italian origin.

Craniosynostosis: prenatal diagnosis by means of ultrasound and SSSE-MRI. Family series with report of neurodevelopmental outcome and review of the literature.

INTRODUCTION: Craniosynostosis is a condition characterized by a premature closure of one or more skull sutures and refers to a wide spectrum of cranial malformation with an estimated birth of 1:2,000-1:4,000 live births. Four receptors (FGFR 1, FGFR 2, FGFR 3, FGFR 4) involving mutation in the fibroblast growth factor have been identified. MATERIALS AND METHODS: Two cases occurred in the same family and diagnosed prenatally by means of ultrasound, and antenatal and postnatal MR imaging are reported. Molecular biology regarding identification of craniosynostosis type has been analyzed. A revision of the medical literature is also provided. CONCLUSION: The premature closure of sagittal suture is characterized by a disproportionately large occipito-frontal and short biparietal diameter (scaphocephaly). The prenatal ultrasound diagnosis of craniosynostosis in utero may be difficult and be suspected when the cephalic index, the cranial shape or the fetal face shape are abnormal. Fetal karyotype is recommended and DNA testing plays a critical role in achieving an appropriate diagnosis, when possible. The prognosis of craniosynostosis is primarily dependent on the presence of associated anomalies as craniosynostosis are correlated with three to fivefold increased risk for cognitive disabilities.

Different mechanisms cause imprinting defects at the IGF2/H19 locus in Beckwith-Wiedemann syndrome and Wilms' tumour.

The parent of origin-dependent expression of the IGF2 and H19 genes is controlled by the imprinting centre 1 (IC1) consisting in a methylation-sensitive chromatin insulator. Deletions removing part of IC1 have been found in patients affected by the overgrowth- and tumour-associated Beckwith-Wiedemann syndrome (BWS). These mutations result in the hypermethylation of the remaining IC1 region, loss of IGF2/H19 imprinting and fully penetrant BWS phenotype when maternally transmitted. We now report that 12 additional cases with IC1 hypermethylation have a similar clinical phenotype but showed neither a detectable deletion nor other mutation in the local vicinity. Likewise, no IC1 deletion was detected in 40 sporadic non-syndromic Wilms' tumours. A detailed analysis of the BWS patients showed that the hypermethylation variably affected the IC1 region and was generally mosaic. We observed that all these cases were sporadic and in at least two families affected and unaffected members shared the same maternal IC1 allele but not the abnormal maternal chromosome epigenotype. Furthermore, the chromosome with the imprinting defect derived from either the maternal grandfather or maternal grandmother. Overall, these results indicate that methylation-imprinting defects at the IGF2-H19 locus can result from inherited mutations of the IC and have high recurrence risk or arise independently from the sequence context and generally not transmitted to the progeny. Despite these differences, the epigenetic abnormalities are usually present in the patients in the mosaic form and probably acquired by post-zygotic de novo methylation. Distinguishing between these two groups of cases is important for genetic counselling.

Evidence that polymorphic deletion of the glutathione S-transferase gene, GSTM1, is associated with esophageal atresia.

BACKGROUND: Esophageal atresia (EA) is a life-threatening congenital condition whose etiology and pathogenesis are still poorly understood. An increasing trend of this pathology in some Italian regions suggests a possible interaction between xenobiotics and genes involved in detoxification processes during early embryonic development. For the first time polymorphisms of GSTM1, GSTT1, and GSTP1 genes were analyzed in association with EA. METHODS: The study population consisted of 25 EA children, 50 unrelated healthy children, 20 of the EA children's mothers, and 40 unrelated mothers. GSTM1 and GSTT1 null genotypes were identified by PCR amplification, and GSTP1 polymorphism was detected by RFLP analysis. RESULTS: An association was found between homozygosity for the GSTM1 null genotype and EA in affected children (p = 0.0022) and their mothers (p = 0.022). No association was found between GSTT1 and GSTP1 polymorphisms and EA children or their mothers. CONCLUSIONS: Results suggest that the GSTM1(-/-) null genotype may play an important role in the development of EA during early embryogenesis as a consequence of altered detoxification processes both in children and in the mothers. We hypothesize that GSTM1 allelic loss could be responsible for reduced or null catalytic activity in tissues exposed to amniotic fluid, and inefficient detoxification could be a trigger altering proliferation/apoptotic pattern of gut-trachea separation.

Apparent life threatening event and gastric antral ulcer in a full-term infant: any possible relationship?

We describe the case of an apparently healthy newborn infant who in 7th day of life showed an episode of haematemesis and in 13th day of life presented an episode of apparent life threatening event (ALTE). A fibroscopy of the upper digestive tract showed a great ulcer of the gastric antrum and esophagitis limited to the mucosa. Gastrinemia in the blood showed high values (121 pg/ml). The relationship between ALTE and gastric ulcer may be casual, however in literature a gastroenteric cause is present in about 50% of ALTE in which an etiologic cause is found. We speculate that in the present case the increase of gastrin secretion reduced gastric pH which facilitated the onset of gastric ulcer and esophagitis with ALTE due to pain or reflex.

Determinants of neonatal hypoglycemia after antenatal administration of corticosteroids (ACS) for lung maturation: Data from two referral centers and review of the literature.

BACKGROUND: A correlation between ACS and neonatal hypoglycemia has been recently demonstrated. AIMS: The aim of the study was to evaluate the determinants of neonatal hypoglycemia in women exposed to ACS for respiratory distress syndrome prevention. MATERIAL AND METHODS: Retrospective, multicenter, cohort study conducted in two Tertiary University Units. All fetuses delivered from 2016 to 2017 after ACS (two doses i.m. of Betamethasone 12 mg 24 h apart) were considered eligible for the study purpose. The primary outcome was the incidence of hypoglycemia, defined as a glycemic value ≤45 mg/dl within the first 48 h of neonatal life. The effect on neonatal glycaemia due to timing (interval from exposure to delivery) and type (single completed, single partial or repeated course) of ACS administration was also assessed. RESULTS: Overall, 99 neonates met the inclusion criteria. Hypoglycemia occurred in 38/99 (38.4%) of the included newborns. Compared to normoglycemic neonates, those with hypoglycemia had lower gestational age at delivery (33.06 ±â€¯3.37 vs. 35.94 ±â€¯3.17 g; p < 0.0001). Lower birthweight (1747.28 ±â€¯815.29 vs. 2499.24 ±â€¯780.51 g; p < 0.0001), a shorter interval time from administration to delivery (1.85 ±â€¯2.59 vs. 3.34 ±â€¯3.39 weeks; p = 0.02) and a higher incidence of single partial course (23.7 vs. 8.72%; p = 0.03). Multivariate logistic regression found that only birthweight was significantly associated with neonatal hypoglycemia (OR 0.4 95% CI -1.16/-0.04; p < 0.038). CONCLUSION: Hypoglycemia occurs in a large proportion of fetuses exposed to ACS independently from the type of exposure (single partial/single completed) and from the time interval between ACS administration and delivery. Birthweight seems to be the strongest determinant for the occurrence neonatal hypoglycemia after antenatal administration of steroids for lung maturation.

Association of dopamine transporter and monoamine oxidase molecular polymorphisms with sudden infant death syndrome and stillbirth: new insights into the serotonin hypothesis.

Recent findings demonstrated the role of neurotransmitters in the aetiopathogenesis of sudden unexpected deaths in infancy. Although genes involved in serotonin metabolism have been proposed as risk factors for sudden infant death syndrome (SIDS), the contribution of additional neurotransmitters and genes different from the serotonin transporter (SLC6A4, 5-HTT) has not been investigated. Considering the common metabolic pathway and synergism between dopamine and serotonin, the role of dopamine transporter (SLC6A3, DAT) and monoamine oxidase A (MAOA) genes in SIDS and stillbirth (sudden intrauterine unexplained death, SIUD) was investigated. Genotypes and allelic frequencies of DAT and MAOA were determined in 20 SIDS and five stillbirth cases and compared with 150 controls. No association was found between DAT polymorphisms and SIDS either at genotype (P = 0.64) or allelic (P = 0.86) level; however, a highly significant association was found between MAOA genotypes (P = 0.047) and alleles (P = 0.002) regulating different expression patterns (3R/3R vs 3.5R/3.5R + 4R/4R) in SIDS + SIUD and controls. Analysis of combined 5-HTTLPR (serotonin transporter linked polymorphic region)/MAOA genotypes revealed that frequency of L/L-4R/4R genotype combination was eightfold higher in SIDS + SIUD than in controls (P < 0.001). Findings are discussed considering the metabolic association among DAT, 5-HTT and MAOA with special emphasis on the linked action of 5-HTT/MAOA in regulating serotonin metabolism of SIDS and SIUD infants.

Multiple joint dislocations: an additional skeletal finding in Lowry-Wood syndrome?

We report on the case of a 17-year-old boy with clinical features compatible with Lowry-Wood syndrome: microcephaly, short stature, multiple epiphyseal dysplasia, tapetoretinal degeneration, and mental retardation. Bilateral restricted elbow extension, knock knees and hip dislocation were also present. Radiographs showed evidence of radial dislocation due to the absence of the radial heads, lateral dislocation of both patellae, multiple epiphyseal dysplasia that was more severe at the proximal femoral epiphyses, and dislocation of both hips with severe hip dysplasia. The patient developed a behavioral disorder at age 15. Conventional karyotyping was normal (46,XY). Molecular karyotyping, performed through array-based competitive genomic hybridization, showed copy number variants that were probably benign. We suggest that multiple joint dislocations, including the patellae, may be a sign of Lowry-Wood syndrome.

Genes regulating the serotonin metabolic pathway in the brain stem and their role in the etiopathogenesis of the sudden infant death syndrome.

Genotypes and allelic frequencies of TPH2, 5-HTTLPR, the 5-HTT (SLC6A4) intron 2 variable-number tandem repeat (VNTR) region, and the MAOA VNTR region were determined in brain-stem samples of 20 "genuine" SIDS cases and compared with results obtained from 150 healthy controls. The SNP G1463A responsible for 80% functionality loss of TPH2 (tryptophan hydroxylase 2) was not detected, neither in SIDS infants nor in the controls. In contrast, a strict relation was found between the 5-HTTLPR genotype and its allelic frequencies with SIDS cases. The L/L genotype and the long allele (L) of the promoter region of the serotonin transporter were significantly associated (likelihood ratio (LR) test, p<0.001) with the syndrome (L/L, 60% SIDS vs 14% controls; L, 80% SIDS vs 42.6% controls). Polymorphisms of the intron 2 VNTR of the same gene showed a trend for significant differences between genotypes 10/10 and 12/12 (LR test, p=0.068), with the L-12 haplotype being almost twofold in SIDS (44.5%) with respect to controls (23.4%). Differences were even higher considering the genotype combination L/L-12/12 (20% SIDS vs 2.6%), and variations among categories were statistically highly significant (p<0.001). Although additional differences were observed in the frequency of the MAOA (monoamine oxidase A) VNTR genotype 3R/3R between SIDS and controls (respectively 15% vs 26%), the results were not supported by statistical significance. Molecular polymorphisms are discussed considering their functional role in regulating serotonin synthesis (TPH2), neuronal reuptake (5-HTTLPR and 5-HTT intron 2), and catabolism (MAOA) in the nervous system of Italian SIDS infants. Comparisons are made with previous data obtained in different ethnic groups.