Cornelia de Lange Spectrum.

Cornelia de Lange syndrome (CdLS) is a rare congenital developmental disorder with multisystemic involvement. The clinical presentation is highly variable, but the classic phenotype, characterized by distinctive craniofacial features, pre- and postnatal growth retardation, extremity reduction defects, hirsutism and intellectual disability can be distinguished from the nonclassic phenotype, which is generally milder and more difficult to diagnose. In addition, the clinical features overlap with those of other neurodevelopmental disorders, so the use of consensus clinical criteria and artificial intelligence tools may be helpful in confirming the diagnosis. Pathogenic variants in NIPBL, which encodes a protein related to the cohesin complex, have been identified in more than 60% of patients, and pathogenic variants in other genes related to this complex in another 15%: SMC1A, SMC3, RAD21, and HDAC8. Technical advances in large-scale sequencing have allowed the description of additional genes (BRD4, ANKRD11, MAU2), but the lack of molecular diagnosis in 15% of individuals and the substantial clinical heterogeneity of the syndrome suggest that other genes and mechanisms may be involved. Although there is no curative treatment, there are symptomatic/palliative treatments that paediatricians should be aware of. The main medical complication in classic SCdL is gastro-esophageal reflux (GER), which should be treated early.

Assessment of Quality of Life Using the Kidslife Scale in Individuals With Cornelia de Lange Syndrome.

BACKGROUND: Cornelia de Lange syndrome (CdLS) is a rare polymalformative genetic disorder with multisystemic involvement. Despite numerous clinical and molecular studies, the specific evaluation of the quality of life (QoL) and its relationship with syndrome-specific risk factors has not been explored. METHODS: The QoL of 33 individuals diagnosed with CdLS, aged between 4 and 21 years, was assessed using the Kidslife questionnaire. Specifically, the influence of 14 risk factors on overall QoL and 8 of its domains was analyzed. RESULTS: The study revealed below-median QoL (45.3 percentile), with the most affected domains being physical well-being, personal development, and self-determination. When classifying patients based on their QoL and affected domains, variants in the NIPBL gene, clinical scores ≥11, and severe behavioral and communication issues were found to be the main risk factors. CONCLUSIONS: We emphasize the need for a comprehensive approach to CdLS that encompasses clinical, molecular, psychosocial, and emotional aspects. The "Kidslife questionnaire" proved to be a useful tool for evaluating QoL, risk factors, and the effectiveness of implemented strategies. In this study, we underscore the importance of implementing corrective measures to improve the clinical score. Furthermore, we highlight the necessity of applying specific therapies for behavioral problems after ruling out underlying causes such as pain or gastroesophageal reflux and implementing measures that facilitate communication and promote social interaction.

Heart Disease Characterization and Myocardial Strain Analysis in Patients with PACS1 Neurodevelopmental Disorder.

BACKGROUND: PACS1 neurodevelopmental disorder (PACS1-NDD) (MIM# 615009) is a rare autosomal dominant disease characterized by neurodevelopmental delay, dysmorphic facial features, and congenital malformations. Heart disease (HD) is frequently present in individuals with PACS1-NDD, but a compressive review of these anomalies and an evaluation of cardiac function in a cohort of patients are lacking. METHODS: (i) Cardiac evaluation in 11 PACS1-NDD patients was conducted using conventional echocardiography. (ii) Heart function was assessed by tissue Doppler imaging, and two-dimensional speckle tracking was performed in seven patients and matched controls. (iii) This systematic review focused on determining HD prevalence in individuals with PACS1-NDD. RESULTS: In our cohort, 7 of 11 patients presented HD. (Among them, three cases of ascending aortic dilatation (AAD) were detected and one mitral valve prolapse (MVP).) None of the patients showed echocardiographic pathological values, and the left global longitudinal strain was not significantly different between patients and controls (patients -24.26 ± 5.89% vs. controls -20.19 ± 1.75%, p = 0.3176). In the literature review, almost 42% (42/100) of individuals with PACS1-NDD reportedly experienced HD. Septal defects were the most common malformation, followed by patent ductus arteriosus. CONCLUSIONS: Our results show a high prevalence of HD in PACS1-NDD patients; in this way, AAD and MVP are reported for the first time in this syndrome. Furthermore, a detailed cardiac function evaluation in our cohort did not reveal evidence of cardiac dysfunction in individuals with PACS1-NDD. Cardiology evaluation should be included for all individuals with Schuurs-Hoeijmakers syndrome.

Endocrine Evaluation and Homeostatic Model Assessment in Patients with Cornelia de Lange Syndrome.

Objective: The aim of this study was to expand knowledge about endocrine disorders in individuals with Cornelia de Lange syndrome (CdLS), a rare developmental genetic disorder with anomalies in multiple organs and systems. Methods: Hormone levels, clinical scores, anthropometric measurements, and molecular analysis were assessed in 24 individuals with CdLS. Results: Hyperprolactinemia was the most common endocrine disorder. Three patients showed subclinical hypothyroidism. In the gonadotropic axis, mildly delayed puberty was observed, as well as genital anomalies, such as cryptorchidism. Despite short stature, levels of insulin-like growth factor 1 and insulin-like growth factor-binding protein 3 were normal, on average. Three prepubertal individuals without risk factors had higher than normal values for the homeostatic model assessment of insulin resistance (HOMA-IR) and for insulinemia, suggesting insulin resistance. Furthermore, two adults had elevated BMIs associated with HOMA-IR values over the cut-off values. Conclusion: CdLS can lead to dysregulation of the endocrine system, particularly in patients with high HOMA-IR values and insulinemia who are at risk of insulin resistance. Therefore, clinical follow-ups with hormonal assessments are proposed for individuals with CdLS.

Subclinical myocardial dysfunction is revealed by speckle tracking echocardiography in patients with Cornelia de Lange syndrome.

This study assesses a possible cardiac dysfunction in individuals with Cornelia de Lange syndrome (CdLS) without diagnosed congenital heart disease (CHD) and its association with other factors. Twenty patients and 20 controls were included in the study divided into three age-dependent groups (A: < 10 yrs, B: 10-20 yrs, C: > 20 yrs), and were evaluated using conventional echocardiography, tissue doppler imaging (TDI), two-dimensional speckle tracking and genetic and biochemical analyses. The left ventricular global longitudinal strain (GLS) was altered (< 15.9%) in 55% of patients, being pathological in the older group (A: 19.7 ± 6.6; B: -17.2 ± 4.7; C: -13.6 ± 2.9). The speckle tracking technique revealed a downward trend in the values of strain, strain rate and velocity, especially in the oldest group. Likewise, the ejection fraction (LVEF) and shortening fraction (LVFS) values, although preserved, also showed a decreased with age (p < 0.05). The analytical markers of cardiovascular risk and cardiac function showed no alterations. The molecular analyses revealed 16 individuals carrying pathogenic variants in NIPBL, two with variants in SMC1A, one with a variant in RAD21 and one with a HDAC8 variant. This is the first systematic approach that demonstrates that individuals with CdLS may present early cardiomyopathy, which can be detected by speckle tracking technique even before the appearance of clinical symptoms and the alteration of other echocardiographic or analytical parameters. For all these reasons, cardiological followup is suggested even in the absence of CHD, especially from adolescence onwards.

Case report: A novel case of parental mosaicism in SMC1A gene causes inherited Cornelia de Lange syndrome.

Ultimate advances in genetic technologies have permitted the detection of transmitted cases of congenital diseases due to parental gonadosomatic mosaicism. Regarding Cornelia de Lange syndrome (CdLS), up to date, only a few cases are known to follow this inheritance pattern. However, the high prevalence of somatic mosaicism recently reported in this syndrome (∼13%), together with the disparity observed in tissue distribution of the causal variant, suggests that its prevalence in this disorder could be underestimated. Here, we report a new case of parental gonadosomatic mosaicism in SMC1A gene that causes inherited CdLS, in which the mother of the patient carries the causative variant in very low allele frequencies in buccal swab and blood. While the affected child presents with typical CdLS phenotype, his mother does not show any clinical manifestations. As regards SMC1A, the difficulty of clinical identification of carrier females has been already recognized, as well as the gender differences observed in CdLS expressivity when the causal variant is found in this gene. Currently, the use of DNA deep-sequencing techniques is highly recommended when it comes to molecular diagnosis of patients, as well as in co-segregation studies. These enable us to uncover gonadosomatic mosaic events in asymptomatic or oligosymptomatic parents that had been overlooked so far, which might have great implications regarding genetic counseling for recurrence risk.

Molecular Basis of the Schuurs-Hoeijmakers Syndrome: What We Know about the Gene and the PACS-1 Protein and Novel Therapeutic Approaches.

The Schuurs−Hoeijmakers syndrome (SHMS) or PACS1 Neurodevelopment Disorder (PACS1-NDD) is a rare autosomal dominant disease caused by mutations in the PACS1 gene. To date, only 87 patients have been reported and, surprisingly, most of them carry the same variant (c.607C>T; p.R203W). The most relevant clinical features of the syndrome include neurodevelopment delay, seizures or a recognizable facial phenotype. Moreover, some of these characteristics overlap with other syndromes, such as the PACS2 or Wdr37 syndromes. The encoded protein phosphofurin acid cluster sorting 1 (PACS-1) is able to bind to different client proteins and direct them to their subcellular final locations. Therefore, although its main function is protein trafficking, it could perform other roles related to its client proteins. In patients with PACS1-NDD, a gain-of-function or a dominant negative mechanism for the mutated protein has been suggested. This, together with the fact that most of the patients carry the same genetic variant, makes it a good candidate for novel therapeutic approaches directed to decreasing the toxic effect of the mutated protein. Some of these strategies include the use of antisense oligonucleotides (ASOs) or targeting of its client proteins.

A Novel Intragenic Duplication in the HDAC8 Gene Underlying a Case of Cornelia de Lange Syndrome.

Cornelia de Lange syndrome (CdLS) is a multisystemic genetic disorder characterized by distinctive facial features, growth retardation, and intellectual disability, as well as various systemic conditions. It is caused by genetic variants in genes related to the cohesin complex. Single-nucleotide variations are the best-known genetic cause of CdLS; however, copy number variants (CNVs) clearly underlie a substantial proportion of cases of the syndrome. The NIPBL gene was thought to be the locus within which clinically relevant CNVs contributed to CdLS. However, in the last few years, pathogenic CNVs have been identified in other genes such as HDAC8, RAD21, and SMC1A. Here, we studied an affected girl presenting with a classic CdLS phenotype heterozygous for a de novo ~32 kbp intragenic duplication affecting exon 10 of HDAC8. Molecular analyses revealed an alteration in the physiological splicing that included a 96 bp insertion between exons 9 and 10 of the main transcript of HDAC8. The aberrant transcript was predicted to generate a truncated protein whose accessibility to the active center was restricted, showing reduced ease of substrate entry into the mutated enzyme. Lastly, we conclude that the duplication is responsible for the patient's phenotype, highlighting the contribution of CNVs as a molecular cause underlying CdLS.

Clinical relevance of postzygotic mosaicism in Cornelia de Lange syndrome and purifying selection of NIPBL variants in blood.

Postzygotic mosaicism (PZM) in NIPBL is a strong source of causality for Cornelia de Lange syndrome (CdLS) that can have major clinical implications. Here, we further delineate the role of somatic mosaicism in CdLS by describing a series of 11 unreported patients with mosaic disease-causing variants in NIPBL and performing a retrospective cohort study from a Spanish CdLS diagnostic center. By reviewing the literature and combining our findings with previously published data, we demonstrate a negative selection against somatic deleterious NIPBL variants in blood. Furthermore, the analysis of all reported cases indicates an unusual high prevalence of mosaicism in CdLS, occurring in 13.1% of patients with a positive molecular diagnosis. It is worth noting that most of the affected individuals with mosaicism have a clinical phenotype at least as severe as those with constitutive pathogenic variants. However, the type of genetic change does not vary between germline and somatic events and, even in the presence of mosaicism, missense substitutions are located preferentially within the HEAT repeat domain of NIPBL. In conclusion, the high prevalence of mosaicism in CdLS as well as the disparity in tissue distribution provide a novel orientation for the clinical management and genetic counselling of families.

Schuurs-Hoeijmakers Syndrome (PACS1 Neurodevelopmental Disorder): Seven Novel Patients and a Review.

Schuurs-Hoeijmakers syndrome (SHMS) or PACS1 Neurodevelopmental disorder is a rare disorder characterized by intellectual disability, abnormal craniofacial features and congenital malformations. SHMS is an autosomal dominant hereditary disease caused by pathogenic variants in the PACS1 gene. PACS1 is a trans-Golgi-membrane traffic regulator that directs protein cargo and several viral envelope proteins. It is upregulated during human embryonic brain development and has low expression after birth. So far, only 54 patients with SHMS have been reported. In this work, we report on seven new identified SHMS individuals with the classical c.607C > T: p.Arg206Trp PACS1 pathogenic variant and review clinical and molecular aspects of all the patients reported in the literature, providing a summary of clinical findings grouped as very frequent (≥75% of patients), frequent (50-74%), infrequent (26-49%) and rare (less than ≤25%).

Heterozygous de novo variants in CSNK1G1 are associated with syndromic developmental delay and autism spectrum disorder.

The gamma-1 isoform of casein kinase 1, the protein encoded by CSNK1G1, is involved in the growth and morphogenesis of cells. This protein is expressed ubiquitously among many tissue types, including the brain, where it regulates the phosphorylation of N-methyl-D-aspartate receptors and plays a role in synaptic transmission. One prior individual with a de novo variant in CSNK1G presenting with severe developmental delay and early-onset epilepsy has been reported. Here we report an updated clinical history of this previously published case, as well as four additional individuals with de novo variants in CSNK1G1 identified via microarray-based comparative genomic hybridization, exome, or genome sequencing. All individuals (n = 5) had developmental delay. At least three individuals had diagnoses of autism spectrum disorder. All participants were noted to have dysmorphic facial features, although the reported findings varied widely and therefore may not clearly be recognizable. None of the participants had additional major malformations. Taken together, our data suggest that CSNK1G1 may be a cause of syndromic developmental delay and possibly autism spectrum disorder.

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.

MAU2 and NIPBL Variants Impair the Heterodimerization of the Cohesin Loader Subunits and Cause Cornelia de Lange Syndrome.

The NIPBL/MAU2 heterodimer loads cohesin onto chromatin. Mutations in NIPBL account for most cases of the rare developmental disorder Cornelia de Lange syndrome (CdLS). Here we report a MAU2 variant causing CdLS, a deletion of seven amino acids that impairs the interaction between MAU2 and the NIPBL N terminus. Investigating this interaction, we discovered that MAU2 and the NIPBL N terminus are largely dispensable for normal cohesin and NIPBL function in cells with a NIPBL early truncating mutation. Despite a predicted fatal outcome of an out-of-frame single nucleotide duplication in NIPBL, engineered in two different cell lines, alternative translation initiation yields a form of NIPBL missing N-terminal residues. This form cannot interact with MAU2, but binds DNA and mediates cohesin loading. Altogether, our work reveals that cohesin loading can occur independently of functional NIPBL/MAU2 complexes and highlights a novel mechanism protective against out-of-frame mutations that is potentially relevant for other genetic conditions.

Delineation of phenotypes and genotypes related to cohesin structural protein RAD21.

RAD21 encodes a key component of the cohesin complex, and variants in RAD21 have been associated with Cornelia de Lange Syndrome (CdLS). Limited information on phenotypes attributable to RAD21 variants and genotype-phenotype relationships is currently published. We gathered a series of 49 individuals from 33 families with RAD21 alterations [24 different intragenic sequence variants (2 recurrent), 7 unique microdeletions], including 24 hitherto unpublished cases. We evaluated consequences of 12 intragenic variants by protein modelling and molecular dynamic studies. Full clinical information was available for 29 individuals. Their phenotype is an attenuated CdLS phenotype compared to that caused by variants in NIPBL or SMC1A for facial morphology, limb anomalies, and especially for cognition and behavior. In the 20 individuals with limited clinical information, additional phenotypes include Mungan syndrome (in patients with biallelic variants) and holoprosencephaly, with or without CdLS characteristics. We describe several additional cases with phenotypes including sclerocornea, in which involvement of the RAD21 variant is uncertain. Variants were frequently familial, and genotype-phenotype analyses demonstrated striking interfamilial and intrafamilial variability. Careful phenotyping is essential in interpreting consequences of RAD21 variants, and protein modeling and dynamics can be helpful in determining pathogenicity. The current study should be helpful when counseling families with a RAD21 variation.

Evaluating Face2Gene as a Tool to Identify Cornelia de Lange Syndrome by Facial Phenotypes.

Characteristic or classic phenotype of Cornelia de Lange syndrome (CdLS) is associated with a recognisable facial pattern. However, the heterogeneity in causal genes and the presence of overlapping syndromes have made it increasingly difficult to diagnose only by clinical features. DeepGestalt technology, and its app Face2Gene, is having a growing impact on the diagnosis and management of genetic diseases by analysing the features of affected individuals. Here, we performed a phenotypic study on a cohort of 49 individuals harbouring causative variants in known CdLS genes in order to evaluate Face2Gene utility and sensitivity in the clinical diagnosis of CdLS. Based on the profile images of patients, a diagnosis of CdLS was within the top five predicted syndromes for 97.9% of our cases and even listed as first prediction for 83.7%. The age of patients did not seem to affect the prediction accuracy, whereas our results indicate a correlation between the clinical score and affected genes. Furthermore, each gene presents a different pattern recognition that may be used to develop new neural networks with the goal of separating different genetic subtypes in CdLS. Overall, we conclude that computer-assisted image analysis based on deep learning could support the clinical diagnosis of CdLS.

The gene encoding the ketogenic enzyme HMGCS2 displays a unique expression during gonad development in mice.

Disorders/differences of sex development (DSD) cause profound psychological and reproductive consequences for the affected individuals, however, most are still unexplained at the molecular level. Here, we present a novel gene, 3-hydroxy-3-methylglutaryl coenzyme A synthase 2 (HMGCS2), encoding a metabolic enzyme in the liver important for energy production from fatty acids, that shows an unusual expression pattern in developing fetal mouse gonads. Shortly after gonadal sex determination it is up-regulated in the developing testes following a very similar spatial and temporal pattern as the male-determining gene Sry in Sertoli cells before switching to ovarian enriched expression. To test if Hmgcs2 is important for gonad development in mammals, we pursued two lines of investigations. Firstly, we generated Hmgcs2-null mice using CRISPR/Cas9 and found that these mice had gonads that developed normally even on a sensitized background. Secondly, we screened 46,XY DSD patients with gonadal dysgenesis and identified two unrelated patients with a deletion and a deleterious missense variant in HMGCS2 respectively. However, both variants were heterozygous, suggesting that HMGCS2 might not be the causative gene. Analysis of a larger number of patients in the future might shed more light into the possible association of HMGCS2 with human gonadal development.

More Than One HMG-CoA Lyase: The Classical Mitochondrial Enzyme Plus the Peroxisomal and the Cytosolic Ones.

There are three human enzymes with HMG-CoA lyase activity that are able to synthesize ketone bodies in different subcellular compartments. The mitochondrial HMG-CoA lyase was the first to be described, and catalyzes the cleavage of 3-hydroxy-3-methylglutaryl CoA to acetoacetate and acetyl-CoA, the common final step in ketogenesis and leucine catabolism. This protein is mainly expressed in the liver and its function is metabolic, since it produces ketone bodies as energetic fuels when glucose levels are low. Another isoform is encoded by the same gene for the mitochondrial HMG-CoA lyase (HMGCL), but it is located in peroxisomes. The last HMG-CoA lyase to be described is encoded by a different gene, HMGCLL1, and is located in the cytosolic side of the endoplasmic reticulum membrane. Some activity assays and tissue distribution of this enzyme have shown the brain and lung as key tissues for studying its function. Although the roles of the peroxisomal and cytosolic HMG-CoA lyases remain unknown, recent studies highlight the role of ketone bodies in metabolic remodeling, homeostasis, and signaling, providing new insights into the molecular and cellular function of these enzymes.

Diagnosis and management of Cornelia de Lange syndrome: first international consensus statement.

Cornelia de Lange syndrome (CdLS) is an archetypical genetic syndrome that is characterized by intellectual disability, well-defined facial features, upper limb anomalies and atypical growth, among numerous other signs and symptoms. It is caused by variants in any one of seven genes, all of which have a structural or regulatory function in the cohesin complex. Although recent advances in next-generation sequencing have improved molecular diagnostics, marked heterogeneity exists in clinical and molecular diagnostic approaches and care practices worldwide. Here, we outline a series of recommendations that document the consensus of a group of international experts on clinical diagnostic criteria, both for classic CdLS and non-classic CdLS phenotypes, molecular investigations, long-term management and care planning.