Pichurin, Pavel N.

DDX3X (Xp11.4) encodes a DEAD‐box RNA helicase that escapes X chromosome inactivation. Pathogenic variants in DDX3X have been shown to cause X‐linked intellectual disability (ID) (MRX102, MIM: 300958). The phenotypes associated with DDX3X variants are heterogeneous and include brain and behavioral abnormalities, microcephaly, hypotonia, and movement disorders and/or spasticity. The majority of DDX3X variants described are de novo mutations in females with ID. In contrast, most male DDX3X variants are inherited from an unaffected mother, with one documented exception being a recently identified de novo splice site variant. It has been suggested, therefore, that DDX3X exerts its effects through haploinsufficiency in females, and that affected males carry hypomorphic alleles that retain partial function. Given the lack of male de novo DDX3X variants, loss‐of‐function variants in this gene are suspected to be male lethal. Through whole‐exome sequencing, we identified three unrelated males with hemizygous missense DDX3X variants and ID. All three variants were confirmed by Sanger sequencing, with two established as de novo. In silico analyses were supportive of pathogenicity. We report the male phenotypes and compare them to phenotypes observed in previously reported male and female patients. In conclusion, we propose that de novo DDX3X variants are not necessarily male lethal and should be considered as a cause of syndromic ID in both males and females.

SOX2 is a transcription factor that is essential for maintenance of pluripotency and has several conserved roles in early embryonic development. Heterozygous loss‐of‐function variants in SOX2 are identified in approximately 40% of all cases of bilateral anophthalmia/micropthalmia (A/M). Increasingly SOX2 mutation‐positive patients without major eye findings, but with a range of other developmental disorders including autism, mild to moderate intellectual disability with or without structural brain changes, esophageal atresia, urogenital anomalies, and endocrinopathy are being reported, suggesting that the clinical phenotype associated with SOX2 loss is much broader than previously appreciated. In this report we describe six new cases, four of which carry novel pathogenic SOX2 variants. Four cases presented with bilateral anophthalmia in addition to extraocular involvement. Another individual presented with only unilateral anophthalmia. One individual did not have any eye findings but presented with a suprasellar teratoma in infancy and was found to have the recurrent c.70del20 mutation in SOX2 (c.70_89del, p.Asn24Argfs*65). This is this first time this tumor type has been reported in the context of a de novo SOX2 mutation. Notably, individuals with hypothalamic hamartomas and slow‐growing hypothalamo‐pituitary tumors have been reported previously, but it is still unclear how SOX2 loss contributes to their formation.

ACTB encodes the β-actin, and pathogenic variations in this gene have typically been associated with Baraitser-Winter cerebrofrontofacial syndrome, a congenital malformation syndrome characterized by short stature, craniofacial anomalies, and cerebral anomalies. Here, we describe the third case with the p.Arg183Trp variant in ACTB causing juvenile-onset dystonia. Our patient has severe, intractable dystonia, developmental delay, and sensorineural hearing loss, besides hyperintensities in the caudate nuclei and putamen on the brain MRI, which is a distinct but overlapping phenotype with the previously reported case of identical twins with the same alteration in ACTB.

Abstract Background Gastrointestinal ( GI ) manifestations are found in Ehlers Danlos syndrome ( EDS ) hypermobility subtype ( HM ). We aimed to assess associations between EDS HM and other EDS subtypes with GI manifestations. Methods We reviewed medical records of EDS patients evaluated at Mayo Clinic's Medical Genetics Clinic 1994–2013. We extracted information regarding EDS subtypes, GI manifestations, and treatments. Key Results We identified 687 patients; 378 (56%) had associated GI manifestations (female 86.8%, diagnosis mean age 29.6 years). Of the patients identified, 58.9% (43/73) had EDS classic, 57.5% (271/471) EDS HM , 47.3% (27/57) EDS vascular subtypes. In addition, 86 patients had EDS that could not be classified in any of those three subtypes. Commonest GI symptoms were: abdominal pain (56.1%), nausea (42.3%), constipation (38.6%), heartburn (37.6%), and irritable bowel syndrome‐like symptoms (27.5%). Many GI symptoms were commoner in EDS HM than the other subtypes together. Among 37.8% of the 378 patients who underwent esophagogastroduodenoscopy, the commonest abnormalities were gastritis, hiatal hernia and reflux esophagitis. Abnormal gastric emptying was observed in 22.3% (17/76): 11.8% delayed and 10.5% accelerated. Colonic transit was abnormal in 28.3% (13/46): 19.6% delayed and 8.7% accelerated. Rectal evacuation disorder was confirmed in 18/30 patients who underwent anorectal manometry. Angiography showed aneurysms in abdominal vessels in EDS vascular type. Proton pump inhibitors (38%) and drugs for constipation (23%) were the most commonly used medications. A minority underwent colectomy (2.9%) or small bowel surgery (4%). Conclusions & Inferences EDS HM and other subtypes should be considered in patients with chronic functional GI symptoms and abdominal vascular lesions.

AbstractIntellectual disability is a heterogeneous disorder with a wide phenotypic spectrum. Over 1,700 OMIM genes have been associated with this condition, many of which reside on the X‐chromosome. The IQSEC2 gene is located on chromosome Xp11.22 and is known to play a significant role in the maintenance and homeostasis of the brain. Mutations in IQSEC2 have been historically associated with nonsyndromic X‐linked intellectual disability. Case reports of affected probands show phenotypic overlap with conditions associated with pathogenic MECP2, FOXG1, CDKL5, and MEF2C gene mutations. Affected individuals, however, have also been identified as presenting with additional clinical features including seizures, autistic‐behavior, psychiatric problems, and delayed language skills. To our knowledge, only 5 deleterious mutations and 2 intragenic duplications have been previously reported in IQSEC2. Here we report two novel IQSEC2 de novo truncating mutations identified through diagnostic exome sequencing in two severely affected unrelated male probands manifesting developmental delay, seizures, hypotonia, plagiocephaly, and abnormal MRI findings. Overall, diagnostic exome sequencing established a molecular diagnosis for two patients in whom traditional testing methods were uninformative while expanding on the mutational and phenotypic spectrum. In addition, our data suggests that IQSEC2 may be more common than previously appreciated, accounting for approximately 9 % (2/22) of positive findings among patients with seizures referred for diagnostic exome sequencing. Further, these data supports recently published data suggesting that IQSEC2 plays a more significant role in the development of X‐linked intellectual disability with seizures than previously anticipated.