Project description:Cornelia de Lange Syndrome (CdLS) is a rare congenital genetic disease causing abnormal unique facial phenotypes, several defects in organs and body parts, and mental disorder or intellectual disorder traits. Main causes of CdLS have been reported as variants in cohesin complex genes, in which mutations in the NIPBL gene have been estimated to account for up to 80%. Our study included three Vietnamese patients with typical CdLS phenotypes. Whole exome sequencing revealed two known heterozygous mutations c.6697G>A (p.Val2233Met) and c.2602C>T (p.Arg868X), and a novel heterozygous mutation c.4504delG (p.Val1502fsX87) in the NIPBL gene of the three patients. In silico analyses of the identified mutations predicted possible damaging and truncating effects on the NIPBL protein. Inherited analyses in the patients' families showed that all of the mutations are de novo. Our results lead a definitive diagnosis of patients with CdLS and expand the spectrum of mutations in the NIPBL gene. These findings also confirm whole exome sequencing is an efficient tool for genetic screening of CdLS.
Project description:Both children (one boy and one girl) experienced disease onset in infancy and visited the hospital due to growth retardation. They had unusual facies including thick hair, arched and confluent eyebrows, long and curly eyelashes, short nose, and micrognathia. Patient 1 had congenital heart disease (atrial septal defect and pulmonary stenosis) and special dermatoglyph (a single palmar crease). Patient 2 had cleft palate and moderate-to-severe deafness. Clinical features suggested Cornelia de Lange syndrome in both children. High-throughput sequencing was used to detect the seven known pathogenic genes of Cornelia de Lange syndrome, i.e., the NIPBL, SMC1A, SMC3, HDAC8, RAD21, EP300, and ANKRD11 genes. Sanger sequencing was used to analyze and verify gene mutations. Both patients were found to have novel mutations in the NIPBL gene. One patient had a frameshift mutation in exon 45, c.7834dupA, which caused early termination of translation and produced truncated protein p.R2612fsX20. The other patient had a nonsense mutation, c.505C>T, which caused a premature stop codon and produced truncated protein Q169X. Such mutations were not found in their parents or 50 unrelated healthy individuals.
Project description:Cornelia de Lange syndrome is a dominantly inherited, genetically heterogeneous and clinically variable syndrome with multiple congenital anomalies and developmental delay. Gastrointestinal anomalies are common and an important cause of morbidity and mortality. We report on a newborn with a molecularly confirmed Cornelia de Lange syndrome who had an imperforate anus. This is the third report of Cornelia de Lange syndrome and imperforate anus.
Project description:Cornelia de Lange syndrome (CdLS) is a rare multisystemic congenital anomaly disorder that is characterised by intellectual disability and growth retardation, congenital heart defects, intestinal anomalies, facial dysmorphism (including synophyris and high arched eyebrows) and limb reduction defects. Mutations in three cohesin-associated genes encoding a key regulator (NIPBL, chr 5p13.2) and one structural component of the cohesin ring (SMC1A, chr Xp11) occur in about 65% of CdLS patients. NIPBL is the major causative gene, and accounts for 40-60% of CdLS patients as shown by a number of mutational screening studies that indicate a wide mutational repertoire of mainly small deletions and point mutations. Only a few data are available concerning the occurrence of large NIPBL rearrangements or intragenic deletions or duplications involving whole exons. We used multiplex ligation-dependent probe amplification (MLPA) to study 132 CdLS patients negative to the standard mutation NIPBL test out of a cohort of 200 CdLS patients. A total of 7 out of 132 patients were found to carry NIPBL alterations, including two large gene deletions extending beyond the gene, four intragenic multi- or single-exon deletions and one single-exon duplication. These findings show that MLPA leads to a 5.3% increase in the detection of mutations when used in addition to the standard NIPBL scan, and contributes per se to the molecular diagnosis of 3.5% (7/200) of clinically diagnosed CdLS patients. It is recommended that MLPA be included in the CdLS diagnostic flow chart.
Project description:Cornelia de Lange syndrome (CdLS) is a rare multi-system genetic disorder characterised by growth and developmental delay, distinctive facial dysmorphism, limb malformations and multiple organ defects. The disease is caused by mutations in genes responsible for the formation and regulation of cohesin complex. About half of the cases result from mutations in the NIPBL gene coding delangin, a protein regulating the initialisation of cohesion. To date, approximately 250 point mutations have been identified in more than 300 CdLS patients worldwide. In the present study, conducted on a group of 64 unrelated Polish CdLS patients, 25 various NIPBL sequence variants, including 22 novel point mutations, were detected. Additionally, large genomic deletions on chromosome 5p13 encompassing the NIPBL gene locus were detected in two patients with the most severe CdLS phenotype. Taken together, 42 % of patients were found to have a deleterious alteration affecting the NIPBL gene, by and large private ones (89 %). The review of the types of mutations found so far in Polish patients, their frequency and correlation with the severity of the observed phenotype shows that Polish CdLS cases do not significantly differ from other populations.
Project description:A male infant at 36 weeks gestation was born by section. At 20 weeks of gestation, congenital diaphragmatic hernia and sacrococcygeal teratoma had been seen on ultrasound. At birth, the infant had features suggestive of Cornelia de Lange syndrome (CdLS). He remained hypoxic despite aggressive ventilatory manoeuvres and was palliated. At postmortem, the lungs were hypoplastic. In CdLS, mutations in NIPBL are found in around 50% of cases. Mutation analysis, including multiplex ligation dependent probe amplification of the NIPBL gene from the DNA extracted from peripheral blood lymphocytes was negative, but microarray comparative genomic hybridisation on DNA from skin fibroblast showed a 0.13Mb deletion on chromosome 5p13. The deleted region includes exons 42-47 of the NIPBL gene. It is important to perform NIBPL mutation analysis on DNA from more than one tissue when testing for CdLS.
Project description:Cornelia de Lange Syndrome (CdLS) is a well described multiple malformation syndrome caused by alterations in genes encoding subunits or regulators of the cohesin complex. In approximately 70% of CdLS patients, pathogenic NIPBL variants are detected and 15% of them are predicted to affect splicing. Moreover, a large portion of genetic variants in NIPBL was shown to be somatic mosaicism. Here we report two family members with different expression of the CdLS phenotype. In both individuals, a c.869-2A>G (r.869_1495del) substitution was detected, affecting a conserved splice-acceptor site. Deep sequencing revealed the presence of somatic mosaicism in the mother. The substitution was detected in 23% of the sequencing reads using DNA derived from blood samples and 51% in DNA from buccal swabs. The analysis of blood DNA of the son excluded the presence of somatic mosaicism. Correlation of molecular and clinical data revealed that various distribution of genetic alteration in different cell types had an impact on the expression of observed clinical features in both individuals.
Project description:Cornelia de Lange syndrome (CdLS) is a developmental multisystem disorder frequently associated with mutations in NIPBL. CdLS is thought to arise from developmental gene regulation defects, but how NIPBL mutations cause these is unknown. Here we show that several NIPBL mutations impair the DNA loop extrusion activity of cohesin. Because this activity is required for the formation of chromatin loops and topologically associating domains, which have important roles in gene regulation, our results suggest that defects in cohesin-mediated loop extrusion contribute to the etiology of CdLS by altering interactions between developmental genes and their enhancers.
Project description:BACKGROUND: Cornelia de Lange syndrome (CdLS) is a dominantly inherited disorder characterized by facial dysmorphism, growth and cognitive impairment, limb malformations and multiple organ involvement. Mutations in NIPBL gene account for about 60% of patients with CdLS. This gene encodes a key regulator of the Cohesin complex, which controls sister chromatid segregation during both mitosis and meiosis. Turner syndrome (TS) results from the partial or complete absence of one of the X chromosomes, usually associated with congenital lymphedema, short stature, and gonadal dysgenesis. CASE PRESENTATION: Here we report a four-year-old female with CdLS due to a frameshift mutation in the NIPBL gene (c.1445_1448delGAGA), who also had a tissue-specific mosaic 45,X/46,XX karyotype. The patient showed a severe form of CdLS with craniofacial dysmorphism, pre- and post-natal growth delay, cardiovascular abnormalities, hirsutism and severe psychomotor retardation with behavioural problems. She also presented with minor clinical features consistent with TS, including peripheral lymphedema and webbed neck. The NIPBL mutation was present in the two tissues analysed from different embryonic origins (peripheral blood lymphocytes and oral mucosa epithelial cells). However, the percentage of cells with monosomy X was low and variable in tissues. These findings indicate that, ontogenically, the NIPBL mutation may have appeared before the mosaic monosomy X. CONCLUSIONS: The coexistence in several patients of these two rare disorders raises the issue of whether there is indeed a cause-effect association. The detailed clinical descriptions indicate predominant CdLS phenotype, although additional TS manifestations may appear in adolescence.
Project description:Cornelia de Lange syndrome (CdLS) is a multisystem congenital anomaly disorder characterized by mental retardation, limb abnormalities, distinctive facial features, and hirsutism. Mutations in three genes involved in sister chromatid cohesion, NIPBL, SMC1A, and SMC3, account for ~55% of CdLS cases. The molecular etiology of a significant fraction of CdLS cases remains unknown. We hypothesized that large genomic rearrangements of cohesin complex subunit genes may play a role in the molecular etiology of this disorder.Custom high-resolution oligonucleotide array comparative genomic hybridization analyses interrogating candidate cohesin genes and breakpoint junction sequencing of identified genomic variants were performed.Of the 162 patients with CdLS, for whom mutations in known CdLS genes were previously negative by sequencing, deletions containing NIPBL exons were observed in 7 subjects (~5%). Breakpoint sequences in five patients implicated microhomology-mediated replicative mechanisms-such as serial replication slippage and fork stalling and template switching/microhomology-mediated break-induced replication-as a potential predominant contributor to these copy number variations. Most deletions are predicted to result in haploinsufficiency due to heterozygous loss-of-function mutations; such mutations may result in a more severe CdLS phenotype.Our findings suggest a potential clinical utility to testing for copy number variations involving NIPBL when clinically diagnosed CdLS cases are mutation-negative by DNA-sequencing studies.