Clinical implications of the family history in patients with lung cancer: a systematic review of the literature and a new cross-sectional/prospective study design (FAHIC: lung).

Compared to other malignancies, few studies have investigated the role of family history of cancer (FHC) in patients with lung cancer, yielding largely heterogeneous results. We performed a systematic literature review in accordance with PRISMA guidelines, searching the PubMed and Scopus databases from their inception to November 25, 2023, to identify studies reporting on the role of FHC in patients with lung cancer. A total of 53 articles were included, most with a retrospective design and encompassing a variety of geographical areas and ethnicities.Thirty studies (56.6%) assessed patients with non-small cell lung cancer (NSCLC), while 17 studies (32.1%) assessed patients with mixed histologies. Overall, the rates of FHC ranged from 8.3 to 68.9%, and the rates of family history of lung cancer ranged from 2 to 46.8%. Twenty-seven studies investigated FHC as a potential risk factor for lung cancer, with more than half reporting an increased risk for subjects with FHC. Five studies reported on the potential role of FHC in determining clinical outcomes, and twelve studies examined the relationship between FHC and germline mutations. Notably, only one study reported a significantly increased rate of germline mutations, including ATM, BRCA2, and TP53, for patients with a family history of lung cancer compared to those without, but both groups had a low prevalence of mutations (< 1%).The FAHIC-Lung (NCT06196424) is the first cross-sectional/prospective study specifically developed to identify FHC patterns and within-family clusters of other risk factors, including smoking, to guide patients with NSCLC to systematic genetic counseling. Acknowledging the largely heterogeneous results of our systematic review and considering the clinical implications of detecting pathogenic germline variants (PGVs), the FAHIC-lung study aims to identify patients potentially enriched with PGVs/likely PGVs to direct them to germline screening outside of the research setting.

A new gene for autosomal dominant facial palsy/migraine identified in a family by whole exome sequencing.

BACKGROUND: Facial palsy manifests as unilateral or bilateral weakness and inability to move some of the facial muscles. The aetiology may be different including idiopathic, trauma, infections or brain tumours or it can be associated with chronic neurological diseases. For instance, in recurrent migraine, an increased risk of idiopathic facial palsy (often unilateral) has been observed. Migraine is a neurovascular disorder characterized by mild to severe intensity of headaches, often associated with neuro-ophthalmological symptoms. METHODS: A family is reported where five members were affected by facial palsy associated with other clinical features including migraine, diplopia, facial swelling, eye conjunctivitis following a vertical transmission. Whole exome sequencing was performed in three members (two affected and one healthy) in order to identify potential variants causative of their phenotype. RESULTS: A missense variant c.304G>A was found leading to the p.(Ala102Thr) substitution in the TRPM8 gene, previously related to migraine by genome wide association studies. This variant was classified as deleterious by several predictor tools, and the mutant residue was predicted to alter the protein structure in terms of flexibility and interactions with the surrounding residues. CONCLUSION: These findings suggest that TRPM8 could be a new causative gene further linking migraine and recurrent facial palsy.

Simultaneous presence of Brugada and overgrowth syndromes.

In the present article, we describe the case of a 21-year-old male presenting to the emergency department following a syncopal episode. Physical examination revealed a distinctive facial appearance in the context of an overgrowth syndrome. Also, an ajmaline test was performed because of the evidence of an incomplete right bundle branch block with ST-T segment elevation in the right precordial derivations, revealing a type-1 Brugada electrocardiographic pattern. Considering the high cardiovascular risk phenotype, the patient underwent subcutaneous cardiac defibrillator implantation. The subsequent comprehensive genomic testing analysis led to the diagnosis of a variant of uncertain significance of the nuclear receptor binding SET domain protein 1 (NSD1) gene and a heterozygous mutation of the calsequestrin 2 (CASQ2) gene. NSD1 gene alterations are usually responsible for the Sotos syndrome, characterized by distinctive facial appearance, learning disability, and overgrowth, in addition to cardiac anomalies ranging from single self-limiting alterations to more severe, complex cardiac abnormalities. On the contrary, a compound heterozygous or homozygous alteration of the CASQ2 gene is usually associated with catecholaminergic polymorphic ventricular tachycardia; however, the significance of a merely heterozygous alteration in the CASQ2 gene, as in the present case report, is not yet clear. In conclusion, to the best of our knowledge, this is the first description of the coexisting presence of Brugada and overgrowth syndromes in a single patient.

Emerging from the Darkness. Sudden Cardiac Death in Cardiac Amyloidosis.

Cardiac amyloidosis (CA) manifests as infiltrative cardiomyopathy with a hypertrophic pattern, usually presenting with heart failure with a preserved ejection fraction. In addition, degenerative valvular heart disease, particularly severe aortic stenosis, is commonly seen in patients with CA. However, amyloid fibril deposition might also infiltrate the conduction system and promote the development of electrical disorders, including ventricular tachyarrhythmias, atrio-ventricular block or acute electromechanical dissociation. These manifestations can increase the risk of sudden cardiac death. This review summarises the pathophysiological mechanisms and risk factors for sudden cardiac death in CA and focuses on the major current concerns regarding medical and device management in this challenging scenario.

POLR3A variants in hereditary spastic paraparesis and ataxia: clinical, genetic, and neuroradiological findings in a cohort of Italian patients.

Mutations in POLR3A are characterized by high phenotypic heterogeneity, with manifestations ranging from severe childhood-onset hypomyelinating leukodystrophic syndromes to milder and later-onset gait disorders with central hypomyelination, with or without additional non-neurological signs. Recently, a milder phenotype consisting of late-onset spastic ataxia without hypomyelinating leukodystrophy has been suggested to be specific to the intronic c.1909 + 22G > A mutation in POLR3A. Here, we present 10 patients from 8 unrelated families with POLR3A-related late-onset spastic ataxia, all harboring the c.1909 + 22G > A variant. Most of them showed an ataxic-spastic picture, two a "pure" cerebellar phenotype, and one a "pure" spastic presentation. The non-neurological findings typically associated with POLR3A mutations were absent in all the patients. The main findings on brain MRI were bilateral hyperintensity along the superior cerebellar peduncles on FLAIR sequences, observed in most of the patients, and cerebellar and/or spinal cord atrophy, found in half of the patients. Only one patient exhibited central hypomyelination. The POLR3A mutations present in this cohort were the c.1909 + 22G > A splice site variant found in compound heterozygosity with six additional variants (three missense, two nonsense, one splice) and, in one patient, with a novel large deletion involving exons 14-18. Interestingly, this patient had the most "complex" presentation among those observed in our cohort; it included some neurological and non-neurological features, such as seizures, neurosensory deafness, and lipomas, that have not previously been reported in association with late-onset POLR3A-related disorders, and therefore further expand the phenotype.

Results of a Gene Panel Approach in a Cohort of Patients with Incomplete Distal Renal Tubular Acidosis and Nephrolithiasis.

BACKGROUND: Distal renal tubular acidosis (dRTA) is characterized by an impairment of urinary acidification resulting in metabolic acidosis, hypokalemia, and inappropriately elevated urine pH. If not treated, this chronic condition eventually leads to nephrocalcinosis, nephrolithiasis, impaired renal function, and bone demineralization. dRTA is a well-defined entity that can be diagnosed by genetic testing of 5 genes known to be disease-causative. Incomplete dRTA (idRTA) is defined as impaired urinary acidification that does not lead to overt metabolic acidosis and therefore can be diagnosed if patients fail to adequately acidify urine after an ammonium chloride (NH4Cl) challenge or furosemide and fludrocortisone test. It is still uncertain whether idRTA represents a distinct entity or is part of the dRTA spectrum and whether it is caused by mutations in the same genes of overt dRTA. METHODS: In this cross-sectional study, we investigated a group of 22 stone formers whose clinical features were suspicious of idRTA. They underwent an NH4Cl challenge and were found to have impaired urinary acidification ability. These patients were then analyzed by genetic testing with sequencing of 5 genes: SLC4A1, ATP6V1B1, ATP6V0A4, FOXI1, and WDR72. RESULTS: Two unrelated individuals were found to have two different variants in SLC4A1 that had never been described before. CONCLUSIONS: Our results suggest the involvement of other genes or nongenetic tubular dysfunction in the pathogenesis of idRTA in stone formers. However, genetic testing may represent a cost-effective tool to recognize, treat, and prevent complications in these patients.

Identification of new candidate genes for spina bifida through exome sequencing.

PURPOSE: Neural tube defects are a group of birth defects caused by failure of neural tube closure during development. The etiology of NTD, requiring a complex interaction between environmental and genetic factors, is not well understood. METHODS: We performed whole-exome sequencing (WES) in six trios, with a single affected proband with spina bifida, to identify rare/novel variants as potential causes of the NTD. RESULTS: Our analysis identified four de novo and ten X-linked recessive variants in four of the six probands, all of them in genes previously never implicated in NTD. Among the 14 variants, we ruled out six of them, based on different criteria and pursued the evaluation of eight potential candidates in the following genes: RXRγ, DTX1, COL15A1, ARHGAP36, TKTL1, AMOT, GPR50, and NKRF. The de novo variants where located in the RXRγ, DTX1, and COL15A1 genes while ARHGAP36, TKTL1, AMOT, GPR50, and NKRF carry X-linked recessive variants. This analysis also revealed that four patients presented multiple variants, while we were unable to identify any significant variant in two patients. CONCLUSIONS: Our preliminary conclusion support a major role for the de novo variants with respect to the X-linked recessive variants where the X-linked could represent a contribution to the phenotype in an oligogenic model.

Melorheostosis and Osteopoikilosis Clinical and Molecular Description of an Italian Case Series.

Melorheostosis (MEL) is an uncommon, sclerosing disease, characterised by hyperostosis of long bones, resembling the flowing of candle wax. The disease is sporadic and the pathogenesis is still poorly understood. Occasionally, the same family can include individuals with MEL and Osteopoikilosis (OPK), a disease characterised by multiple round foci of increased bone density. LEMD3 gene mutations are related to OPK and Buschke-Ollendorff Syndrome, a genetic condition in which an association between MEL, OPK and skin lesions is observed. In rare cases, LEMD3 mutations and recently mosaic MAP2K1 gene mutations have been correlated to MEL suggesting that somatic mosaicism could be causative of the disease. In this study, we described the clinical, radiological and molecular findings of 19 individuals with MEL and 8 with OPK and compared the results to the medical literature. The molecular analyses of this case series corroborate the available data in the medical literature, indicating that LEMD3 germline mutations are not a major cause of isolated MEL and reporting five further cases of OPK caused by LEMD3 germline mutations.

Recognizable facial features in patients with alternating hemiplegia of childhood.

Alternating hemiplegia of childhood is an early onset neurodevelopmental disorder characterized by paroxystic episodes of alternating hemiplegia, variable degrees of intellectual disability, and dystonic movements. The main causative gene, ATP1A3, is also responsible for other neurodevelopmental disorders. While the neurological profile of this condition is well defined, the question whether a recognizable pattern of physical anomalies does exist in this condition is still open. We performed a morphological evaluation of 30 patients at different ages. All patients were evaluated independently by each author and evaluation sheets were compared, discussed, and agreed afterwards. This study started before the identification of ATP1A3 as the causative gene, and the patients were selected upon their neurological picture. Four of these 30 patients tested negative for ATP1A3 mutations and were excluded from the present work. On physical ground, almost all patients shared a similar physical phenotype consisting of hypotonia, long face, thin eyebrows, strabismus, hypertelorism, long palpebral fissures, downturned mouth, and slender habitus. Such phenotype is sufficiently typical to generate a recognizable gestalt. We also evaluated patients photographs taken from the parents in early childhood (6-20 months) to delineate a clinical profile possibly recognizable before the neurological signs suggest the diagnosis. Our data suggest that the typical early gestalt is sufficient to advise the molecular analysis of ATP1A3, even in absence of the pathognomonic neurological signs. Finally, since a number of patients is now adult, some information can be drawn on the phenotypic evolution of the facial appearance of patients with alternating hemiplegia of childhood. © 2016 Wiley Periodicals, Inc.

Coding exons function as tissue-specific enhancers of nearby genes.

Enhancers are essential gene regulatory elements whose alteration can lead to morphological differences between species, developmental abnormalities, and human disease. Current strategies to identify enhancers focus primarily on noncoding sequences and tend to exclude protein coding sequences. Here, we analyzed 25 available ChIP-seq data sets that identify enhancers in an unbiased manner (H3K4me1, H3K27ac, and EP300) for peaks that overlap exons. We find that, on average, 7% of all ChIP-seq peaks overlap coding exons (after excluding for peaks that overlap with first exons). By using mouse and zebrafish enhancer assays, we demonstrate that several of these exonic enhancer (eExons) candidates can function as enhancers of their neighboring genes and that the exonic sequence is necessary for enhancer activity. Using ChIP, 3C, and DNA FISH, we further show that one of these exonic limb enhancers, Dync1i1 exon 15, has active enhancer marks and physically interacts with Dlx5/6 promoter regions 900 kb away. In addition, its removal by chromosomal abnormalities in humans could cause split hand and foot malformation 1 (SHFM1), a disorder associated with DLX5/6. These results demonstrate that DNA sequences can have a dual function, operating as coding exons in one tissue and enhancers of nearby gene(s) in another tissue, suggesting that phenotypes resulting from coding mutations could be caused not only by protein alteration but also by disrupting the regulation of another gene.

Functional characterization of tissue-specific enhancers in the DLX5/6 locus.

Disruption of distaless homeobox 5 and 6 (Dlx5/6) in mice results in brain, craniofacial, genital, ear and limb defects. In humans, chromosomal aberrations in the DLX5/6 region, some of which do not encompass DLX5/6, are associated with split hand/foot malformation 1 (SHFM1) as well as intellectual disability, craniofacial anomalies and hearing loss, suggesting that the disruption of DLX5/6 regulatory elements could lead to these abnormalities. Here, we characterized enhancers in the DLX5/6 locus whose tissue-specific expression and genomic location along with previously characterized enhancers correlate with phenotypes observed in individuals with chromosomal abnormalities. By analyzing chromosomal aberrations at 7q21, we refined the minimal SHFM1 critical region and used comparative genomics to select 26 evolutionary conserved non-coding sequences in this critical region for zebrafish enhancer assays. Eight of these sequences were shown to function as brain, olfactory bulb, branchial arch, otic vesicle and fin enhancers, recapitulating dlx5a/6a expression. Using a mouse enhancer assay, several of these zebrafish enhancers showed comparable expression patterns in the branchial arch, otic vesicle, forebrain and/or limb at embryonic day 11.5. Examination of the coordinates of various chromosomal rearrangements in conjunction with the genomic location of these tissue-specific enhancers showed a correlation with the observed clinical abnormalities. Our findings suggest that chromosomal abnormalities that disrupt the function of these tissue-specific enhancers could be the cause of SHFM1 and its associated phenotypes. In addition, they highlight specific enhancers in which mutations could lead to non-syndromic hearing loss, craniofacial defects or limb malformations.

Exploring the Role of the MUTYH Gene in Breast, Ovarian and Endometrial Cancer.

BACKGROUND: MUTYH germline monoallelic variants have been detected in a number of patients affected by breast/ovarian cancer or endometrial cancer, suggesting a potential susceptibility role, though their significance remains elusive since the disease mechanism is normally recessive. Hence, the aim of this research was to explore the hypothesis that a second hit could have arisen in the other allele in the tumor tissue. METHODS: we used Sanger sequencing and immunohistochemistry to search for a second MUTYH variant in the tumoral DNA and to assess protein expression, respectively. RESULTS: we detected one variant of unknown significance, one variant with conflicting interpretation of pathogenicity and three benign/likely benign variants; the MUTYH protein was not detected in the tumor tissue of half of the patients, and in others, its expression was reduced. CONCLUSIONS: our results fail to demonstrate that germinal monoallelic MUTYH variants increase cancer risk through a LOH (loss of heterozygosity) mechanism in the somatic tissue; however, the absence or partial loss of the MUTYH protein in many tumors suggests its dysregulation regardless of MUTYH genetic status.

Emerging Microorganisms and Infectious Diseases: One Health Approach for Health Shared Vision.

Emerging infectious diseases (EIDs) are newly emerging and reemerging infectious diseases. The National Institute of Allergy and Infectious Diseases identifies the following as emerging infectious diseases: SARS, MERS, COVID-19, influenza, fungal diseases, plague, schistosomiasis, smallpox, tick-borne diseases, and West Nile fever. The factors that should be taken into consideration are the genetic adaptation of microbial agents and the characteristics of the human host or environment. The new approach to identifying new possible pathogens will have to go through the One Health approach and omics integration data, which are capable of identifying high-priority microorganisms in a short period of time. New bioinformatics technologies enable global integration and sharing of surveillance data for rapid public health decision-making to detect and prevent epidemics and pandemics, ensuring timely response and effective prevention measures. Machine learning tools are being more frequently utilized in the realm of infectious diseases to predict sepsis in patients, diagnose infectious diseases early, and forecast the effectiveness of treatment or the appropriate choice of antibiotic regimen based on clinical data. We will discuss emerging microorganisms, omics techniques applied to infectious diseases, new computational solutions to evaluate biomarkers, and innovative tools that are useful for integrating omics data and electronic medical records data for the clinical management of emerging infectious diseases.

Exome sequencing of ATP1A3-negative cases of alternating hemiplegia of childhood reveals SCN2A as a novel causative gene.

Alternating hemiplegia of childhood (AHC) is a rare neurodevelopment disorder that is typically characterized by debilitating episodic attacks of hemiplegia, seizures, and intellectual disability. Over 85% of individuals with AHC have a de novo missense variant in ATP1A3 encoding the catalytic α3 subunit of neuronal Na+/K+ ATPases. The remainder of the patients are genetically unexplained. Here, we used next-generation sequencing to search for the genetic cause of 26 ATP1A3-negative index patients with a clinical presentation of AHC or an AHC-like phenotype. Three patients had affected siblings. Using targeted sequencing of exonic, intronic, and flanking regions of ATP1A3 in 22 of the 26 index patients, we found no ultra-rare variants. Using exome sequencing, we identified the likely genetic diagnosis in 9 probands (35%) in five genes, including RHOBTB2 (n = 3), ATP1A2 (n = 3), ANK3 (n = 1), SCN2A (n = 1), and CHD2 (n = 1). In follow-up investigations, two additional ATP1A3-negative individuals were found to have rare missense SCN2A variants, including one de novo likely pathogenic variant and one likely pathogenic variant for which inheritance could not be determined. Functional evaluation of the variants identified in SCN2A and ATP1A2 supports the pathogenicity of the identified variants. Our data show that genetic variants in various neurodevelopmental genes, including SCN2A, lead to AHC or AHC-like presentation. Still, the majority of ATP1A3-negative AHC or AHC-like patients remain unexplained, suggesting that other mutational mechanisms may account for the phenotype or that cases may be explained by oligo- or polygenic risk factors.

Clinical, genetic, and molecular aspects of split-hand/foot malformation: an update.

We here provide an update on the clinical, genetic, and molecular aspects of split-hand/foot malformation (SHFM). This rare condition, affecting 1 in 8,500-25,000 newborns, is extremely complex because of its variability in clinical presentation, irregularities in its inheritance pattern, and the heterogeneity of molecular genetic alterations that can be found in affected individuals. Both syndromal and nonsyndromal forms are reviewed and the major molecular genetic alterations thus far reported in association with SHFM are discussed. This updated overview should be helpful for clinicians in their efforts to make an appropriate clinical and genetic diagnosis, provide an accurate recurrence risk assessment, and formulate a management plan.

RADX Gene Variant May Predispose to Familial Asperger Syndrome.

Asperger syndrome (AS) is a pervasive developmental disorder characterized by general impairment in socialization, stereotypical behavior, defective adaptation to the social context usually without intellectual disability, and some high functioning areas related to memory and mathematics. Clinical criteria are not well defined and the etiology is heterogeneous and mostly unknown. Like in typical autism spectrum disorders (ASD), the genetic background plays a crucial role in AS, and often an almost mendelian segregation can be observed in some families. We performed a whole exome sequencing (WES) in three relatives of a family with vertical transmission of AS-ASD to identify variants in candidate genes segregating with the phenotype. Variant p.(Cys834Ser) in the RADX gene was the only one segregating among all the affected family members. This gene encodes a single-strand DNA binding factor, which mediates the recruitment of genome maintenance proteins to sites of replication stress. Replication stress and genome instability have been reported recently in neural progenitor cells derived from ASD patients, leading to a disruption of long neural genes involved in cell-cell adhesion and migration. We propose RADX as a new gene that when mutated could represent a predisposing factor to AS-ASD.

Deletion of a Single Lysine Residue at Position 292 of CAMK2A Disrupts Protein Function, Causing Severe Epileptic Encephalopathy and Intellectual Disability.

BACKGROUND: The use of NGS technology has rapidly increased during the last decade, and many new monogenic neurodevelopmental disorders have emerged. Pathogenic variants in the neuronal CAMK2A gene have been recently associated with "intellectual developmental disorder, autosomal dominant 53″ (OMIM#617798), a syndrome characterized by variable clinical manifestations including mild to severe intellectual disability, delayed psychomotor development, delayed or absent speech, delayed walking, seizures, dysmorphic features and behavioral psychiatric manifestations as autism spectrum disorders, aggressive behavior, and hyperactivity. CAMK2A (OMIM*114078) encodes for a subunit of the calcium/calmodulin-dependent serine/threonine kinase II (CaMKII), which is predominately expressed in the brain, where it plays critical roles in synaptic plasticity, learning, and memory as well as in neuronal migration. METHODS AND RESULTS: We hereby describe a thirty-five-year-old woman affected by severe intellectual disability with epileptic encephalopathy. We performed exome sequencing and found a de novo heterozygous variant in the CAMK2A gene (NM_171825.2: c.874_876delCTT; p.Lys292del), which was fully correlated with her phenotype. This is the first report of an inframe single amino acid deletion in a patient affected by intellectual developmental disorder autosomal dominant 53. The variant is predicted to affect protein structure and function and interaction with other proteins and hits a crucial functional site. DISCUSSION: We discuss our variant in relation to previously reported variants and with the objective of delineating possible genotype-phenotype correlations.

Melkersson-Rosenthal Syndrome and Migraine: A New Phenotype Associated with SCN1A Variants?

Peripheral facial palsy rarely occurs as part of Melkersson-Rosenthal syndrome (MRS), which is characterized by the classical triad of tongue cheilitis, recurrent episodes of orofacial swelling, and palsy. MRS is a disorder with variable expressivity and clinical as well as genetic heterogeneity; however, the causative gene remains to be identified. Migraine is a common neurological disorder, presenting with or without aura, which may be associated with neurological symptoms. The classical example of monogenic migraine is familial hemiplegic migraine (FHM), which has phenotypic variability in carriers of variants in the same gene or even carriers of the same variant. We present a family in which two sisters displayed recurrent migraines, one of which presented recurrent facial palsy and had clinical diagnosis of MRS. We performed WES and Sanger sequencing for segregation analysis in the available family members. We identified a c.3521C>G missense heterozygous variant in SCN1A carried only by the affected sister. Variants in the SCN1A gene can cause a spectrum of early-onset epileptic encephalopathies, in addition to FHM; therefore, our finding reasonably explains the proband phenotype, in which the main symptom was recurrent facial palsy. This report also adds knowledge to the clinical spectrum of SCN1A alterations and suggests a potential overlap between MRS and FHM.

CHAMP1-related disorders: pathomechanisms triggered by different genomic alterations define distinct nosological categories.

Loss-of-function variants in CHAMP1 were recently described as cause of a neurodevelopmental disorder characterized by intellectual disability (ID), autism, and distinctive facial characteristics. By exome sequencing (ES), we identified a truncating variant in CHAMP1, c.1858A > T (p.Lys620*), in a patient who exhibited a similar phenotype of severe ID and dysmorphisms. Whether haploinsufficiency or a dominant negative effect is the underlying pathomechanism in these cases is a question that still needs to be addressed. By array-CGH, we detected a 194 kb deletion in 13q34 encompassing CHAMP1, CDC16 and UPF3, in another patient who presented with borderline neurodevelopmental impairment and with no dysmorphisms. In a further patient suffering from early onset refractory seizures, we detected by ES a missense variant in CHAMP1, c.67 G > A (p.Gly23Ser). Genomic abnormalities were all de novo in our patients. We reviewed the clinical and the genetic data of patients reported in the literature with: loss-of-function variants in CHAMP1 (total 40); chromosome 13q34 deletions ranging from 1.1 to 4 Mb (total 7) and of the unique patient with a missense variant. We could infer that loss-of-function variants in CHAMP1 cause a homogeneous phenotype with severe ID, autism spectrum disorders (ASD) and highly distinctive facial characteristics through a dominant negative effect. CHAMP1 haploinsufficiency results in borderline ID with negligible consequences on the quality of life. Missense variants give rise to a severe epileptic encephalopathy through gain-of-function mechanism, most likely. We tentatively define for the first time distinct categories among the CHAMP1-related disorder on the basis of pathomechanisms.