Transcriptor co-activator factor 20 gene (TCF20) encodes a nuclear chromatin-binding protein involved in regulation of gene expression. In human pathology, pathogenic variants or deletions in TCF20 were identified in patients with developmental delay, variable intellectual disability and behavioral impairment (OMIM: 618430). The shared core phenotype includes developmental delay, hypotonia, motor delay, autism spectrum disorders, neurobehavioral anomalies, neurological features such as ataxia, seizures, movement disorders, structural brain anomalies, craniofacial features and various congenital anomalies. Most pathogenic variants are loss-of-function variants. Duplication including TCF20 was suspected to cause a neurodevelopmental disorder (NDD) with mirror traits compared to patients with TCF20 deletions. In the present study, we report three patients from three unrelated families with NDD with a de novo duplication at 22q13.2 encompassing TCF20. We propose that the TCF20 duplication could be involved in a new 22q13.2 microduplication syndrome with high penetrance, enlarging the genotype-phenotype knowledge of TCF20-associated NDDs.
Ectodermal dysplasias are a family of genodermatoses commonly associated with variants in the ectodysplasin/NF‐κB or the Wnt/β‐catenin pathways. Both pathways are involved in signal transduction from ectoderm to mesenchyme during the development of ectoderm‐derived structures. Wnt/β‐catenin pathway requires the lymphoid enhancer‐binding factor 1 (LEF1), a nuclear mediator, to activate target gene expression. In mice, targeted inactivation of the LEF1 gene results in a complete block of development of multiple ectodermal appendages. We report two unrelated patients with 4q25 de novo deletion encompassing LEF1, associated with severe oligodontia of primary and permanent dentition, hypotrichosis and hypohidrosis compatible with hypohidrotic ectodermal dysplasia. Taurodontism and a particular alveolar bone defect were also observed in both patients. So far, no pathogenic variants or variations involving the LEF1 gene have been reported in human. We provide further evidence for LEF1 haploinsufficiency role in ectodermal dysplasia and delineate its clinical phenotype.
We report an original association of complex genetic defects in a patient carrying both an 11p paternal duplication, resulting in the double expression of
insulin-like growth factor 2 (IGF2)
, as reported in Beckwith-Wiedemann syndrome, and a 15q terminal deletion, including the
type 1 IGF receptor gene
(
IGF1R
), resulting in haploinsufficiency for this gene. The patient was born with measurements appropriate for her gestational age but experienced growth retardation in early childhood, allowing a better comprehension of the IGF system in the pathophysiology of growth. It is possible that IGF-II plays a key role in fetal growth, independently of IGF1R signaling, and that its role is less important in post-natal growth, leaving IGF-I and growth hormone as the main actors.
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