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Genetic conditions comprise a wide spectrum of different phenotypes, rapidly expanding due to new diagnostic methodologies. Patients' facial features and clinical history represent the key elements leading clinicians to the right diagnosis. CDKL5-early onset epilepsy and Pitt-Hopkins syndrome are two well-known genetic conditions, with a defined phenotype sharing some common characteristics like early-onset epilepsy and hyperventilation episodes. Whilst facial features represent a diagnostic handle in patients with Pitt-Hopkins syndrome, clinical history is crucial in patients carrying a mutation in CDKL5. Here we present the clinical case of a girl evaluated for the first time when she was 24-years old, with a clinical phenotype mimicking Pitt-Hopkins syndrome. Her facial features have become coarser while she was growing up, leading geneticists to raise different clinical hypotheses and to perform several molecular tests before getting the diagnosis of CDKL5-early-epileptic encephalopathy. This finding highlights that although typical facial gestalt has not so far extensively been described in CDKL5 mutated adult patients, peculiar facial features could be present later in life and may let CDKL5-related disorder mimic Pitt Hopkins. Thus, considering atypical Rett syndrome in the differential diagnosis of Pitt Hopkins syndrome could be important to solve complex clinical cases., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Introduction: MED13L-related intellectual disability is characterized by moderate intellectual disability (ID), speech impairment, and dysmorphic facial features. We present 8 patients with MED13L-related intellectual disability and review the literature for phenotypical and genetic aspects of previously described patients., Materials and Methods: In the search for genetic aberrations in individuals with ID, two of the patients were identified by chromosomal microarray analysis, and five by exome sequencing. One of the individuals, suspected of MED13L-related intellectual disability, based on clinical features, was identified by Sanger sequencing., Results: All 8 individuals had de novo MED13L aberrations, including two intragenic microdeletions, two frameshift, three nonsense variants, and one missense variant. Phenotypically, they all had intellectual disability, speech and motor delay, and features of the mouth (open mouth appearance, macroglossia, and/or macrostomia). Two individuals were diagnosed with autism, and one had autistic features. One had complex congenital heart defect, and one had persistent foramen ovale. The literature was reviewed with respect to clinical and dysmorphic features, and genetic aberrations., Conclusions: Even if most clinical features of MED13L-related intellectual disability are rather non-specific, the syndrome may be suspected in some individuals based on the association of developmental delay, speech impairment, bulbous nasal tip, and macroglossia, macrostomia, or open mouth appearance., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Pitt-Hopkins syndrome is a neurodevelopmental disorder characterized by severe intellectual disability and a distinctive facial gestalt. It is caused by haploinsufficiency of the TCF4 gene. The TCF4 protein has different functional domains, with the NLS (nuclear localization signal) domain coded by exons 7-8 and the bHLH (basic Helix-Loop-Helix) domain coded by exon 18. Several alternatively spliced TCF4 variants have been described, allowing for translation of variable protein isoforms. Typical PTHS patients have impairment of at least the bHLH domain. To which extent impairment of the remaining domains contributes to the final phenotype is not clear. There is recent evidence that certain loss-of-function variants disrupting TCF4 are associated with mild ID, but not with typical PTHS. We describe a frameshift-causing partial gene deletion encompassing exons 4-6 of TCF4 in an adult patient with mild ID and nonspecific facial dysmorphisms but without the typical features of PTHS, and a c.520C > T nonsense variant within exon 8 in a child presenting with a severe phenotype largely mimicking PTHS, but lacking the typical facial dysmorphism. Investigation on mRNA, along with literature review, led us to suggest a preliminary phenotypic map of loss-of-function variants affecting TCF4. An intragenic phenotypic map of loss-of-function variants in TCF4 is suggested here for the first time: variants within exons 1-4 and exons 4-6 give rise to a recurrent phenotype with mild ID not in the spectrum of Pitt-Hopkins syndrome (biallelic preservation of both the NLS and bHLH domains); variants within exons 7-8 cause a severe phenotype resembling PTHS but in absence of the typical facial dysmorphism (impairment limited to the NLS domain); variants within exons 9-19 cause typical Pitt-Hopkins syndrome (impairment of at least the bHLH domain). Understanding the TCF4 molecular syndromology can allow for proper nosology in the current era of whole genomic investigations., (Copyright © 2017. Published by Elsevier Masson SAS.)

We report on a 3-year-old male with intellectual disability (ID), characteristic facial features, polydactyly and epilepsy carrying a paternally inherited 3q28 deletion of 1.9 Mb. The father, carrying the same deletion, presents with cleft palate, nail dystrophy and learning difficulties. The deleted region in this family is one of the smallest so far reported among genomic deletions affecting 3q27-3q28 for which some phenotypic descriptions are available. In particular, since the phenotype of our proband is strikingly similar to that previously described in a patient with a 9.3 Mb deletion, the deletion identified in this report contributes to the definition of the molecular boundaries of a genomic region responsible for a distinct clinical phenotype. Within the deleted interval there are 9 annotated genes, including TP63. Gain of function mutations of TP63 are known to be responsible for a group of conditions with distal limb and ectodermal involvement, such as ADULT, EEC, LMS, and SHFM4 syndromes. Interestingly, our cases demonstrate a milder phenotypic effect for loss of function of this gene., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

The ring 14 syndrome is a rare condition, whose precise clinical and genetic characterization is still limited. This review summarizes literature data and it describes our own experience with 27 patients with ring 14 syndrome. Clinically, the ring 14 syndrome is characterized by a recognizable phenotype of shortness of stature, distinctive facial appearance, microcephaly, scoliosis, and ocular abnormalities, consisting mainly of abnormal retinal pigmentation, but also retinitis pigmentosa, strabismus, glaucoma, and abnormal macula. Virtually all patients are intellectually delayed, with aggressive and hyperactive behavior in some. Drug-resistant, mainly focal in type, epilepsy is another highly consistent finding. In our own sample of patients the ring was complete, with no apparent loss of chromosome material, in 6/27 cases, while it showed a small terminal deletion, varying in size from 0.3 to 5 Mb, in the other 21. In two of these a cryptic 14q duplication of 2.5 and 9.7 Mb, respectively, proximal to the deleted segment, was also identified. Deleted rings were 75% paternal and 25% maternal in origin. UPD (14) was excluded in all cases. Based on literature review of linear deletions, affecting either the proximal or the distal 14q region, we could deduce that retinal abnormalities and epilepsy map within the proximal 14q11.2- q12 region. Because this region is preserved in all patients with ring 14, we speculate that genes residing in the proximal 14q interval are disregulated through heterochromatinization spreading from the adjacent short arm of the chromosome. Behavior disorders and susceptibility to infections can be assigned to the 14q32 region, haploinsufficiency being the most likely underlying mechanism., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)