Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cornelia de Lange syndrome (CdLS) is a dominantly inherited developmental disorder characterized by distinctive facial features, mental retardation, and upper limb defects, with the involvement of multiple organs and systems. To date, mutations have been identified in five genes responsible for CdLS: NIPBL, SMC1A, SMC3, RAD21, and HDAC8. Here, we present a clinical and molecular characterization of five unrelated Chinese patients whose clinical presentation is consistent with that of CdLS. There were no chromosomal abnormalities in the five children. In three patients, DNA sequencing revealed a previously reported frameshift mutation c.2479delA (p.Arg827GlyfsX20), and two novel mutations including a heterozygous mutation c.6272 G>T (p.Cys2091Phe) and a frameshift mutation c.1672delA (p.Thr558LeufsX7) in NIPBL. For the remaining patients, large deletions and/or duplications within the NIPBL gene were excluded as playing a role in the pathogenesis, by Multiplex Ligation-dependent Probe Amplification (MLPA) analysis. These findings broaden the mutation spectrum of NIPBL and further our understanding of the diverse and variable effects of NIPBL mutations on CdLS.
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PMID:Two novel NIPBL gene mutations in Chinese patients with Cornelia de Lange syndrome. 2544 6

Genetic variants within components of the cohesin complex (NIPBL, SMC1A, SMC3, RAD21, PDS5, ESCO2, HDAC8) are believed to be responsible for a spectrum of human syndromes known as "cohesinopathies" that includes Cornelia de Lange Syndrome (CdLS). CdLS is a multiple malformation syndrome affecting almost any organ and causing severe developmental delay. Cohesinopathies seem to be caused by dysregulation of specific developmental pathways downstream of mutations in cohesin components. However, it is still unclear how mutations in different components of the cohesin complex affect the output of gene regulation. In this study, zebrafish embryos and SMC1A-mutated patient-derived fibroblasts were used to analyze abnormalities induced by SMC1A loss of function. We show that the knockdown of smc1a in zebrafish impairs neural development, increases apoptosis, and specifically down-regulates Ccnd1 levels. The same down-regulation of cohesin targets is observed in SMC1A-mutated patient fibroblasts. Previously, we have demonstrated that haploinsufficiency of NIPBL produces similar effects in zebrafish and in patients fibroblasts indicating a possible common feature for neurological defects and mental retardation in cohesinopathies. Interestingly, expression analysis of Smc1a and Nipbl in developing mouse embryos reveals a specific pattern in the hindbrain, suggesting a role for cohesins in neural development in vertebrates.
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PMID:CyclinD1 Down-Regulation and Increased Apoptosis Are Common Features of Cohesinopathies. 2620 33

Robert syndrome (RBS) and Cornelia de Lange syndrome (CdLS) are human developmental disorders characterized by craniofacial deformities, limb malformation and mental retardation. These birth defects are collectively termed cohesinopathies as both arise from mutations in cohesion genes. CdLS arises due to autosomal dominant mutations or haploinsufficiencies in cohesin subunits (SMC1A, SMC3 and RAD21) or cohesin auxiliary factors (NIPBL and HDAC8) that result in transcriptional dysregulation of developmental programs. RBS arises due to autosomal recessive mutations in cohesin auxiliary factor ESCO2, the gene that encodes an N-acetyltransferase which targets the SMC3 subunit of the cohesin complex. The mechanism that underlies RBS, however, remains unknown. A popular model states that RBS arises due to mitotic failure and loss of progenitor stem cells through apoptosis. Previous findings in the zebrafish regenerating fin, however, suggest that Esco2-knockdown results in transcription dysregulation, independent of apoptosis, similar to that observed in CdLS patients. Previously, we used the clinically relevant CX43 to demonstrate a transcriptional role for Esco2. CX43 is a gap junction gene conserved among all vertebrates that is required for direct cell-cell communication between adjacent cells such that cx43 mutations result in oculodentodigital dysplasia. Here, we show that morpholino-mediated knockdown of smc3 reduces cx43 expression and perturbs zebrafish bone and tissue regeneration similar to those previously reported for esco2 knockdown. Also similar to Esco2-dependent phenotypes, Smc3-dependent bone and tissue regeneration defects are rescued by transgenic Cx43 overexpression, suggesting that Smc3 and Esco2 cooperatively act to regulate cx43 transcription. In support of this model, chromatin immunoprecipitation assays reveal that Smc3 binds to a discrete region of the cx43 promoter, suggesting that Esco2 exerts transcriptional regulation of cx43 through modification of Smc3 bound to the cx43 promoter. These findings have the potential to unify RBS and CdLS as transcription-based mechanisms.
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PMID:Cohesin mediates Esco2-dependent transcriptional regulation in a zebrafish regenerating fin model of Roberts Syndrome. 2908 13

We report a patient with developmental delay, brachydactyly type E, short stature, and tetralogy of Fallot. Brachydactyly-mental retardation syndrome (BDMR) was suspected based on the phenotype; however, array CGH excluded a 2q37 deletion, but identified a deletion encompassing the SHOX gene. BDMR is characterized by cognitive impairment, skeletal abnormalities involving hands and feet, short stature, and overweight. Most affected individuals carry relatively large 2q37 deletions encompassing HDAC4. This gene encodes a histone deacetylase involved in epigenetic regulation of cell growth and differentiation, specifically during endochondral bone formation in chondrocyte hypertrophy. Since SHOX haploinsufficiency can cause skeletal defects and short stature but would not fully explain the clinical picture of this patient, exome sequencing was performed, and a heterozygous HDAC8 frameshift mutation was identified. HDAC8 is a distinct histone deacetylase involved in cohesin recycling and is responsible for an X-linked dominant Cornelia de Lange-like phenotype. A new blended clinical phenotype may be explained by the result of a dual molecular diagnosis, which represents a combination of 2 independent genetic defects, with relevant implications for genetic counseling, clinical management, and prognosis.
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PMID:HDAC8 Loss of Function and SHOX Haploinsufficiency: Two Independent Genetic Defects Responsible for a Complex Phenotype. 3093 54

Cornelia de Lange syndrome (CdLS) is a rare autosomal-dominant genetic disorder characterised by prenatal and postnatal growth and mental retardation, facial dysmorphism and upper limb abnormalities. Germline mutations of cohesin complex genes SMC1A, SMC3, RAD21 or their regulators NIPBL and HDAC8 have been identified in CdLS as well as somatic mutations in myeloid disorders. We describe the first case of a paediatric patient with CdLS with B-cell precursor Acute Lymphoblastic Leukaemia (ALL). The patient did not show any unusual cytogenetic abnormality, and he was enrolled into the high risk arm of AIEOP-BFM ALL2009 protocol because of slow early response, but 3 years after discontinuation, he experienced an ALL relapse. We identified a heterozygous mutation in exon 46 of NIPBL, causing frameshift and a premature stop codon (RNA-Targeted Next generation Sequencing Analysis). The analysis of the family indicated a de novo origin of this previously not reported deleterious variant. As for somatic cohesin mutations in acute myeloid leukaemia, also this ALL case was not affected by aneuploidy, thus suggesting a major impact of the non-canonical role of NIPBL in gene regulation. A potential biological role of NIPBL in leukaemia has still to be dissected.
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PMID:First evidence of a paediatric patient with Cornelia de Lange syndrome with acute lymphoblastic leukaemia. 3094 35