OBJECTIVE: To explore the clinical characteristics and variant of CREBBP gene in a fetus with Rubinstein-Taybi syndrome (RSTS).
METHODS: A fetus with RSTS diagnosed at the Third Affiliated Hospital of Zhengzhou University in August 2022 was selected as the study subject. Clinical data, amniotic fluid sample of the fetus and peripheral blood samples of its parents were collected for whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing.
RESULTS: Foot malformation, cerebellar vermis agenesis, brain agenesis, polysyndactyly of the big toes and other phenotypes were found by prenatal ultrasound. WES revealed that the fetus has harbored a heterozygous c.4684G>T (p.E1562*) variant in exon 28 of the CREBBP gene (NM_004380.3), which was de novo in origin. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was predicted to be pathogenic (PVS1+PS2_Moderate+PM2_Supporting). After genetic counseling, the couple had opted to terminate the pregnancy and refused autopsy of the fetus.
CONCLUSIONS: The c.4684G>T (p.E1562*) variant of the CREBBP gene probably underlay the RSTS in this fetus. The newly discovered variant has enriched the mutational spectrum of the CREBBP gene and illustrated that WES is an efficient tool for the prenatal diagnosis of RSTS.

Rubinstein-Taybi syndrome (RTS) is a rare genetic disorder characterized by intellectual disability, facial dysmorphisms, and enlarged thumbs and halluces. Approximately 55% of RTS cases result from pathogenic variants in the CREBBP gene, with an additional 8% linked to the EP300 gene. Given the close relationship between these two genes and their involvement in epigenomic modulation, RTS is grouped into chromatinopathies. The extensive clinical heterogeneity observed in RTS, coupled with the growing number of disorders involving the epigenetic machinery, poses a challenge to a phenotype-based diagnostic approach for these conditions. Here, we describe the first case of a patient clinically diagnosed with RTS with a CREBBP truncating variant in mosaic form. We also review previously described cases of mosaicism in CREBBP and apply clinical diagnostic guidelines to these patients, confirming the good specificity of the consensus. Nonetheless, these reports raise questions about the potential underdiagnosis of milder cases of RTS. The application of a targeted phenotype-based approach, coupled with high-depth NGS, may enhance the diagnostic yield of whole-exome sequencing (WES) in mild and mosaic conditions.

UNASSIGNED: A case report of a six-year and five-month-old female admitted with typical symptoms of Rubinstein-Taybi syndrome is presented. Clinical and rehabilitation settings where she acquired her reading, writing, and communication skills are described.
UNASSIGNED: Because of her cognitive disabilities, a multidisciplinary and long-term intervention (2014-2020) was necessary. Treatment included orthoptic, psychomotor, logopedic, occupational, and neuropsychological care. Her family and school were involved.
UNASSIGNED: Increased attention led to decreased dysfunctional behaviors. Test results are still below average, but there has been significant improvement. Better communication skills resulted from increased phonetic range, improved articulation, lexical-semantic structure, comprehension, and production of sentences. Digital technologies played a significant role in enhancing her communication skills, not just in social interactions but also in school activities. The patient is oriented in time and space with the help of agendas and calendars. She can express her needs and compose concise narratives. As a result of acquiring functional skills, she is better equipped to handle real-life situations, which has led to increased social and family activities.
UNASSIGNED: This case report highlights the importance of personalized rehabilitation programs. Obtaining an early genetic diagnosis is crucial for timely tailored rehabilitation, and any delays in this process can hinder progress.

Rubinstein Taybi Syndrome (RSTS) is a rare genetic disorder which is caused by mutations in either CREBBP or EP300. RSTS with mutations in CREBBP is known as RSTS-1. We have generated an induced pluripotent stem cell (iPSC) line, IGIBi018-A from an Indian RSTS-patient using the episomal reprogramming method. The CREBBP gene in the patient harbours a nonsense mutation at position NM_004380.3(c.6876 del C). IGIBi018-A iPSC showed expression of pluripotent stem cell markers, has a normal karyotype and could be differentiated into three germ layers. This iPSC line will help to explore the role of CREBBP in RSTS associated developmental defects.

暂无摘要。

Histone deacetylases (HDACs) are enzymes pivotal for histone modification (i.e. acetylation marks removal), chromatin accessibility and gene expression regulation. Class I HDACs (including HDAC1, 2, 3, 8) are ubiquitously expressed and they often participate in multi-molecular protein complexes. To date, three neurodevelopmental disorders caused by mutations in genes encoding for HDACs (HDAC4, HDAC6 and HDAC8) and thus belonging to the group of chromatinopathies, have been described. We performed whole exome sequencing (WES) for a patient (#249) clinically diagnosed with the chromatinopathy Rubinstein-Taybi syndrome (RSTS) but negative for mutations in RSTS genes, identifying a de novo frameshift variant in HDAC2 gene. We then investigated its molecular effects in lymphoblastoid cell lines (LCLs) derived from the patient compared to LCLs from healthy donors (HD). As the variant was predicted to be likely pathogenetic and to affect the sequence of nuclear localization signal, we performed immunocytochemistry and lysates fractionation, observing a nuclear mis-localization of HDAC2 compared to HD LCLs. In addition, HDAC2 total protein abundance resulted altered in patient, and we found that newly identified variant in HDAC2 affects also acetylation levels, with significant difference in acetylation pattern among patient #249, HD and RSTS cells and in expression of a known molecular target. Remarkably, RNA-seq performed on #249, HD and RSTS cells shows differentially expressed genes (DEGs) common to #249 and RSTS. Interestingly, our reported patient was clinically diagnosed with RSTS, a chromatinopathy which known causative genes encode for enzymes antagonizing HDACs. These results support the role of HDAC2 as causative gene for chromatinopathies, strengthening the genotype-phenotype correlations in this relevant group of disorders.

暂无摘要。

Pterygium is a benign, wing-shaped fibrovascular overgrowth of subconjunctival tissue that can encroach over the cornea. This condition usually occurs in individuals aged 20-40 years but is rarely seen in children. We report a case of an infant with Rubenstein-Taybi syndrome presenting with nebulo-macular corneal opacity and congenital pterygium. On examination under anaesthesia, bilateral infero-nasal nebulo-macular corneal opacity (6 × 5 mm) with a whitish pink tissue originating from nasal bulbar conjunctiva was noticed. The probe test was negative for this tissue. To the best of our knowledge, only two other cases of congenital pterygium have been reported in the literature. The presence of this anomaly supports the hypothesis of genetic factors having a role in the development of pterygium.

CREB-binding protein (CBP, encoded by CREBBP) and its paralog E1A-associated protein (p300, encoded by EP300) are involved in histone acetylation and transcriptional regulation. Variants that produce a null allele or disrupt the catalytic domain of either protein cause Rubinstein-Taybi syndrome (RSTS), while pathogenic missense and in-frame indel variants in parts of exons 30 and 31 cause phenotypes recently described as Menke-Hennekam syndrome (MKHK). To distinguish MKHK subtypes and define their characteristics, molecular and extended clinical data on 82 individuals (54 unpublished) with variants affecting CBP (n = 71) or p300 (n = 11) (NP_004371.2 residues 1,705-1,875 and NP_001420.2 residues 1,668-1,833, respectively) were summarized. Additionally, genome-wide DNA methylation profiles were assessed in DNA extracted from whole peripheral blood from 54 individuals. Most variants clustered closely around the zinc-binding residues of two zinc-finger domains (ZZ and TAZ2) and within the first α helix of the fourth intrinsically disordered linker (ID4) of CBP/p300. Domain-specific methylation profiles were discerned for the ZZ domain in CBP/p300 (found in nine out of 10 tested individuals) and TAZ2 domain in CBP (in 14 out of 20), while a domain-specific diagnostic episignature was refined for the ID4 domain in CBP/p300 (in 21 out of 21). Phenotypes including intellectual disability of varying degree and distinct physical features were defined for each of the regions. These findings demonstrate existence of at least three MKHK subtypes, which are domain specific (MKHK-ZZ, MKHK-TAZ2, and MKHK-ID4) rather than gene specific (CREBBP/EP300). DNA methylation episignatures enable stratification of molecular pathophysiologic entities within a gene or across a family of paralogous genes.

Objective: To investigate the phenotypes of Rubinstein-Taybi syndrome (RSTS) caused by variants in the CREBBP or EP300 gene, and the correlation between genotype and phenotype. Methods: This case series study was performed on pediatric patients who were referred to the Children\'s Hospital of Capital Institute of Pediatrics between January 2013 and July 2022. Both point variant and copy number deletion in CREBBP or EP300 gene were detected by whole exome sequencing, chromosomal microarray analysis, or copy number variation sequencing (CNV-seq). The variant categories were summarized and phenotype numbers were re-visited for RSTS patients. Based on variant types, the patients were divided into different groups (point variant or copy number deletion, EP300 or CREBBP point variant, and loss of function or missense variant). Phenotype counts between different groups were compared using the rank-sum test of two independent samples. Results: A total of 21 RSTS patients were recruited, including 12 males and 9 females, with ages ranging from 1 month to 14 years and 2 months. Among them, 67% (14/21) had point variants, and 33% (7/21) had copy number deletions. Out of these, 20 variants (95%) were de novo. Among 20 patients finishing phenotype count during re-visit, 95% (19/20) of the patients exhibited developmental delays before the age of 2 years. Additionally, 80% (16/20) of the patients had distinctive facial features. Considering phenotype count, no statistically significant difference was found between point variant (14 cases) and copy number deletion (6 cases) (5.0 (3.0, 7.0) vs. 5.0 (2.5, 5.3), Z=0.75, P=0.452), CREBBP (10 cases) and EP300 gene (4 cases) point variant (5.0 (3.8, 7.0) vs. 4.0 (2.0, 6.0), Z=1.14, P=0.253), and loss of function (9 cases) and missense (5 cases) variant (6.0 (4.5, 7.0) vs. 3.0 (2.5, 5.5), Z=1.54, P=0.121). Conclusions: Patients with RSTS primarily exhibit developmental delays in early childhood. Specific facial features serve as suggested signs of genetic testing. However, no significant genotype-phenotype correlation is found.
目的： 总结Rubinstein-Taybi综合征（RSTS）的基因变异类型和临床表型特点，探讨其基因型与表型的相关性。 方法： 病例系列研究，收集2013年1月至2022年7月就诊于首都儿科研究所附属儿童医院，通过全外显子测序或染色体芯片、拷贝数变异测序，检出CREBBP或EP300基因变异的21例RSTS患儿的病例资料。总结其基因变异类型并回访其表型数目。根据变异类型将患儿分别分为点变异或拷贝数缺失组、EP300基因或CREBBP基因变异组、功能丧失或错义变异组。组间表型数目比较采用两独立样本秩和检验。 结果： 21例患儿中男12例、女9例，年龄范围为1月龄至14岁2月龄，14例（67%）点变异，7例（33%）拷贝数缺失；其中20例（95%）为新生变异。20例患儿随访获得详细表型数目，95%（19/20）在2岁以内出现神经发育迟缓，80%（16/20）具有特殊面容。组间表型数目比较，点变异组（14例）与拷贝数缺失变异组（6例）［5.0（3.0，7.0）比5.0（2.5，5.3）个，Z=0.75，P=0.452］；CREBBP基因组（10例）与EP300基因变异组（4例）［5.0（3.8，7.0）比4.0（2.0，6.0）个，Z=1.14，P=0.253］；功能丧失变异组（9例）与错义变异组（5例）［6.0（4.5，7.0）比3.0（2.5，5.5）个，Z=1.54，P=0.121］，差异均无统计学意义。 结论： RSTS患儿主要临床表型为神经发育迟缓，特定面容为疑似患者寻求基因检测提供依据。基因变异类型和表型数目无关。.