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Genes Apr 2024Infantile onset transient hypomyelination (IOTH) is a rare form of leukodystrophy that is associated with transient motor impairment and delayed central nervous system...
Infantile onset transient hypomyelination (IOTH) is a rare form of leukodystrophy that is associated with transient motor impairment and delayed central nervous system myelination. Here, we report a case of a new mutation in the transmembrane protein 63A () gene identified using Whole-Exome Sequencing (WES) in an 8.5-year-old boy with clinical symptoms similar to IOTH. The patient exhibited a mild developmental delay, including hypotonia and delayed motor milestones, as well as some notable phenotypic characteristics, such as macrocephaly and macrosomia. Despite the absence of early neuroimaging, genetic testing revealed a paternally inherited variant in (NM_14698.3:c.220A>T;p:(Arg74*)), potentially linked to infantile transient hypomyelinating leukodystrophy type 19. Our findings in this study and the patient's favorable clinical course underscore the potential for successful myelination even with delayed initiation and may contribute to a better understanding of the genotype-phenotype correlation in IOTH, emphasizing the importance of genetic analysis in unresolved developmental delay cases and providing critical insights for accurate diagnosis, prognosis and potential therapeutic strategies in rare leukodystrophies.
Topics: Child; Humans; Male; Codon, Nonsense; Exome Sequencing; Genetic Association Studies; Hereditary Central Nervous System Demyelinating Diseases; Heterozygote; Membrane Proteins
PubMed: 38790154
DOI: 10.3390/genes15050525 -
Hormones (Athens, Greece) May 2024Silver-Russell syndrome 5 (SRS5) is characterized by asymmetric intrauterine growth restriction (IUGR), poor postnatal growth, macrocephaly at birth, and feeding...
Silver-Russell syndrome 5 (SRS5) is characterized by asymmetric intrauterine growth restriction (IUGR), poor postnatal growth, macrocephaly at birth, and feeding difficulties. Other possible features include triangular shaped face, prominent forehead, hypertelorism, epicanthus, micrognathia, brachydactyly, clinodactyly of the 5th finger, and syndactyly of the 2nd and 3rd toes. Pathogenic variants of the HMGA2 (high mobility group AT-hook 2) gene, on chromosome 12q14, which regulates the transcription of growth factor IGF2, have recently been associated with this syndrome. Herein, we present a 2.5-year-old boy with growth delay, SRS-like phenotype, and a variant of uncertain significance in the HMGA2 gene, which has not, to the best of our knowledge, been described to date in the medical literature. So far, 28 pathogenic variants of the HMGA2 gene in patients with clinical SRS phenotype have recently been reported. Therefore, HMGA2 gene testing should always be done in SRS patients who are found to be negative for the typical 11p15 (epi)mutations and matUPD7, while the mutations should also be added to growth retardation disorder panels.
PubMed: 38789914
DOI: 10.1007/s42000-024-00562-x -
Epileptic Disorders : International... May 2024Pathogenic variants in CACNA1E are associated with early-onset epileptic and developmental encephalopathy (DEE). Severe to profound global developmental delay,...
Pathogenic variants in CACNA1E are associated with early-onset epileptic and developmental encephalopathy (DEE). Severe to profound global developmental delay, early-onset refractory seizures, severe hypotonia, and macrocephaly are the main clinical features. Patients harboring the recurrent CACNA1E variant p.(Gly352Arg) typically present with the combination of early-onset DEE, dystonia/dyskinesia, and contractures. We describe a 2-year-and-11-month-old girl carrying the p.(Gly352Arg) CACNA1E variant. She has a severe DEE with very frequent drug-resistant seizures, profound hypotonia, and episodes of dystonia and dyskinesia. Long-term video-EEG-monitoring documented subsequent tonic asymmetric seizures during wakefulness and mild paroxysmal dyskinesias of the trunk out of sleep which were thought to be a movement disorder and instead turned out to be focal hyperkinetic seizures. This is the first documented description of the EEG findings in this disorder. Our report highlights a possible overlap between cortical and subcortical phenomena in CACNA1E-DEE. We also underline how a careful electro-clinical evaluation might be necessary for a correct discernment between the two disorders, playing a fundamental role in the clinical assessment and proper management of children with CACNA1E-DEE.
PubMed: 38780451
DOI: 10.1002/epd2.20242 -
Genetics in Medicine : Official Journal... May 2024The function of FAM177A1 and its relationship to human disease is largely unknown. Recent studies have demonstrated FAM177A1 to be a critical immune-associated gene. One...
PURPOSE
The function of FAM177A1 and its relationship to human disease is largely unknown. Recent studies have demonstrated FAM177A1 to be a critical immune-associated gene. One previous case study has linked FAM177A1 to a neurodevelopmental disorder in four siblings.
METHODS
We identified five individuals from three unrelated families with biallelic variants in FAM177A1. The physiological function of FAM177A1 was studied in a zebrafish model organism and human cell lines with loss-of-function variants similar to the affected cohort.
RESULTS
These individuals share a characteristic phenotype defined by macrocephaly, global developmental delay, intellectual disability, seizures, behavioral abnormalities, hypotonia, and gait disturbance. We show that FAM177A1 localizes to the Golgi complex in mammalian and zebrafish cells. Intersection of the RNA-seq and metabolomic datasets from FAM177A1-deficient human fibroblasts and whole zebrafish larvae demonstrated dysregulation of pathways associated with apoptosis, inflammation, and negative regulation of cell proliferation.
CONCLUSION
Our data sheds light on the emerging function of FAM177A1 and defines FAM177A1-related neurodevelopmental disorder as a new clinical entity.
PubMed: 38767059
DOI: 10.1016/j.gim.2024.101166 -
PLoS Biology May 2024Autism spectrum disorders (ASD) frequently accompany macrocephaly, which often involves hydrocephalic enlargement of brain ventricles. Katnal2 is a...
Autism spectrum disorders (ASD) frequently accompany macrocephaly, which often involves hydrocephalic enlargement of brain ventricles. Katnal2 is a microtubule-regulatory protein strongly linked to ASD, but it remains unclear whether Katnal2 knockout (KO) in mice leads to microtubule- and ASD-related molecular, synaptic, brain, and behavioral phenotypes. We found that Katnal2-KO mice display ASD-like social communication deficits and age-dependent progressive ventricular enlargements. The latter involves increased length and beating frequency of motile cilia on ependymal cells lining ventricles. Katnal2-KO hippocampal neurons surrounded by enlarged lateral ventricles show progressive synaptic deficits that correlate with ASD-like transcriptomic changes involving synaptic gene down-regulation. Importantly, early postnatal Katnal2 re-expression prevents ciliary, ventricular, and behavioral phenotypes in Katnal2-KO adults, suggesting a causal relationship and a potential treatment. Therefore, Katnal2 negatively regulates ependymal ciliary function and its deletion in mice leads to ependymal ciliary hyperfunction and hydrocephalus accompanying ASD-related behavioral, synaptic, and transcriptomic changes.
Topics: Animals; Male; Mice; Autism Spectrum Disorder; Behavior, Animal; Cilia; Disease Models, Animal; Ependyma; Hippocampus; Hydrocephalus; Katanin; Mice, Inbred C57BL; Mice, Knockout; Neurons; Phenotype; Synapses; Transcriptome
PubMed: 38718086
DOI: 10.1371/journal.pbio.3002596 -
Clinical Epigenetics May 2024Temple syndrome (TS14) is a rare imprinting disorder caused by maternal UPD14, imprinting defects or paternal microdeletions which lead to an increase in the maternal...
BACKGROUND
Temple syndrome (TS14) is a rare imprinting disorder caused by maternal UPD14, imprinting defects or paternal microdeletions which lead to an increase in the maternal expressed genes and a silencing the paternally expressed genes in the 14q32 imprinted domain. Classical TS14 phenotypic features include pre- and postnatal short stature, small hands and feet, muscular hypotonia, motor delay, feeding difficulties, weight gain, premature puberty along and precocious puberty.
METHODS
An exon array comparative genomic hybridization was performed on a patient affected by psychomotor and language delay, muscular hypotonia, relative macrocephaly, and small hand and feet at two years old. At 6 years of age, the proband presented with precocious thelarche. Genes dosage and methylation within the 14q32 region were analyzed by MS-MLPA. Bisulfite PCR and pyrosequencing were employed to quantification methylation at the four known imprinted differentially methylated regions (DMR) within the 14q32 domain: DLK1 DMR, IG-DMR, MEG3 DMR and MEG8 DMR.
RESULTS
The patient had inherited a 69 Kb deletion, encompassing the entire DLK1 gene, on the paternal allele. Relative hypermethylation of the two maternally methylated intervals, DLK1 and MEG8 DMRs, was observed along with normal methylation level at IG-DMR and MEG3 DMR, resulting in a phenotype consistent with TS14. Additional family members with the deletion showed modest methylation changes at both the DLK1 and MEG8 DMRs consistent with parental transmission.
CONCLUSION
We describe a girl with clinical presentation suggestive of Temple syndrome resulting from a small paternal 14q32 deletion that led to DLK1 whole-gene deletion, as well as hypermethylation of the maternally methylated DLK1-DMR.
Topics: Humans; Calcium-Binding Proteins; DNA Methylation; Chromosomes, Human, Pair 14; Intercellular Signaling Peptides and Proteins; Genomic Imprinting; Membrane Proteins; Child; Male; Comparative Genomic Hybridization; Female; Chromosome Deletion; Child, Preschool; Phenotype; Abnormalities, Multiple; Imprinting Disorders; Muscle Hypotonia; Facies
PubMed: 38715103
DOI: 10.1186/s13148-024-01652-8 -
Cell Reports. Medicine May 2024The size of the human head is highly heritable, but genetic drivers of its variation within the general population remain unmapped. We perform a genome-wide association...
The size of the human head is highly heritable, but genetic drivers of its variation within the general population remain unmapped. We perform a genome-wide association study on head size (N = 80,890) and identify 67 genetic loci, of which 50 are novel. Neuroimaging studies show that 17 variants affect specific brain areas, but most have widespread effects. Gene set enrichment is observed for various cancers and the p53, Wnt, and ErbB signaling pathways. Genes harboring lead variants are enriched for macrocephaly syndrome genes (37-fold) and high-fidelity cancer genes (9-fold), which is not seen for human height variants. Head size variants are also near genes preferentially expressed in intermediate progenitor cells, neural cells linked to evolutionary brain expansion. Our results indicate that genes regulating early brain and cranial growth incline to neoplasia later in life, irrespective of height. This warrants investigation of clinical implications of the link between head size and cancer.
Topics: Humans; Genome-Wide Association Study; Head; Neoplasms; Female; Male; Polymorphism, Single Nucleotide; Genetic Variation; Organ Size; Signal Transduction; Adult; Genetic Predisposition to Disease
PubMed: 38703765
DOI: 10.1016/j.xcrm.2024.101529 -
DNA and Cell Biology May 2024Megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome (MPPH), a type of overgrowth syndrome, is characterized by progressive megalencephaly, cortical brain...
Megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome (MPPH), a type of overgrowth syndrome, is characterized by progressive megalencephaly, cortical brain malformations, and distal limb anomalies. Previous studies have revealed that the overactivity of the phosphatidylinositol 3-kinase-Protein kinase B pathway and the increased cyclin D2 (CCND2) expression were the main factors contributing to this disease. Here, we present the case of a patient who exhibited megalencephaly, polymicrogyria, abnormal neuronal migration, and developmental delay. Serum tandem mass spectrometry and chromosome examination did not detect any metabolic abnormalities or copy number variants. However, whole-exome sequencing and Sanger sequencing revealed a nonsense mutation (NM_001759.3: c.829C>T; p.Gln277X) in the gene of the patient. Bioinformatics analysis predicted that this mutation may disrupt the structure and surface charge of the CCND2 protein. This disruption could potentially prevent polyubiquitination of CCND2, leading to its resistance against degradation. Consequently, this could drive cell division and growth by altering the activity of key cell cycle regulatory nodes, ultimately contributing to the development of MPPH. This study not only presents a new case of MPPH and expands the mutation spectrum of but also enhances our understanding of the mechanisms connecting with overgrowth syndromes.
PubMed: 38700464
DOI: 10.1089/dna.2023.0391 -
International Dental Journal May 2024Patients with PTEN hamartoma tumour syndrome (PHTS) have an increased risk of developing cancer due to a pathogenic germline variant in the PTEN tumour suppressor gene....
AIMS
Patients with PTEN hamartoma tumour syndrome (PHTS) have an increased risk of developing cancer due to a pathogenic germline variant in the PTEN tumour suppressor gene. Early recognition of PHTS facilitates initiation of cancer surveillance which is highly effective in preventing the development of advanced malignancies. PHTS is rare and due to its varied phenotype, even within families, oral abnormalities may be a valuable tool in the identification of these patients at an early stage before cancer development.
MATERIALS AND METHODS
Between 1997 and 2020, phenotypic characteristics were evaluated in 81 paediatric (median age: 9 years) and 86 adult (median age: 40 years) PHTS patients by one of 2 medical experts during yearly surveillance visits at a Dutch PHTS expertise centre. Oral features evaluated included gingival hypertrophy, oral papillomas, and high palate (in adults).
RESULTS
Within adults, gingival hypertrophy was present in 94%, oral papillomas in 88%, and a high palate in 89%. All adult patients had at least one of these oral features, and 99% showed at least 2 oral features. Oral features were less common in paediatric patients, especially under 11 years of age. Gingival hypertrophy was observed in 44% and oral papillomas in 54% of paediatric patients.
CONCLUSIONS
The presence of 2 or 3 oral features may indicate PHTS in adults or adolescents, especially if macrocephaly is present. Dental professionals are well-positioned to recognise these oral manifestations could be related to PHTS. They can initiate an overall clinical assessment of the patient by alerting the patient's medical practitioner of the findings and the possible need for genetic testing. This could significantly improve outcomes, including life expectancy, for patients and possibly for their relatives.
CLINICAL RELEVANCE
Dental professionals are ideally placed to recognise oral features and initiate early assessment of PHTS which could significantly improve patient outcomes.
PubMed: 38697906
DOI: 10.1016/j.identj.2024.04.014