Patients with KCNH1-related intellectual disability without distinctive features of Zimmermann-Laband/Temple-Baraitser syndrome.

De novo missense variants in KCNH1 encoding Kv10.1 are responsible for two clinically recognisable phenotypes: Temple-Baraitser syndrome (TBS) and Zimmermann-Laband syndrome (ZLS). The clinical overlap between these two syndromes suggests that they belong to a spectrum of KCNH1-related encephalopathies. Affected patients have severe intellectual disability (ID) with or without epilepsy, hypertrichosis and distinctive features such as gingival hyperplasia and nail hypoplasia/aplasia (present in 20/23 reported cases).We report a series of seven patients with ID and de novo pathogenic KCNH1 variants identified by whole-exome sequencing or an epilepsy gene panel in whom the diagnosis of TBS/ZLS had not been first considered. Four of these variants, p.(Thr294Met), p.(Ala492Asp), p.(Thr493Asn) and p.(Gly496Arg), were located in the transmembrane domains S3 and S6 of Kv10.1 and one, p.(Arg693Gln), in its C-terminal cyclic nucleotide-binding homology domain (CNBHD). Clinical reappraisal by the referring clinical geneticists confirmed the absence of the distinctive gingival and nail features of TBS/ZLS.Our study expands the phenotypical spectrum of KCNH1-related encephalopathies to individuals with an attenuated extraneurological phenotype preventing a clinical diagnosis of TBS or ZLS. This subtype may be related to recurrent substitutions of the Gly496, suggesting a genotype-phenotype correlation and, possibly, to variants in the CNBHD domain.

Treacher Collins syndrome: a clinical and molecular study based on a large series of patients.

PURPOSE: Treacher Collins/Franceschetti syndrome (TCS; OMIM 154500) is a disorder of craniofacial development belonging to the heterogeneous group of mandibulofacial dysostoses. TCS is classically characterized by bilateral mandibular and malar hypoplasia, downward-slanting palpebral fissures, and microtia. To date, three genes have been identified in TCS:,TCOF1, POLR1D, and POLR1C. METHODS: We report a clinical and extensive molecular study, including TCOF1, POLR1D, POLR1C, and EFTUD2 genes, in a series of 146 patients with TCS. Phenotype-genotype correlations were investigated for 19 clinical features, between TCOF1 and POLR1D, and the type of mutation or its localization in the TCOF1 gene. RESULTS: We identified 92/146 patients (63%) with a molecular anomaly within TCOF1, 9/146 (6%) within POLR1D, and none within POLR1C. Among the atypical negative patients (with intellectual disability and/or microcephaly), we identified four patients carrying a mutation in EFTUD2 and two patients with 5q32 deletion encompassing TCOF1 and CAMK2A in particular. Congenital cardiac defects occurred more frequently among patients with TCOF1 mutation (7/92, 8%) than reported in the literature. CONCLUSION: Even though TCOF1 and POLR1D were associated with extreme clinical variability, we found no phenotype-genotype correlation. In cases with a typical phenotype of TCS, 6/146 (4%) remained with an unidentified molecular defect.

Clinical and molecular findings in 39 patients with KBG syndrome caused by deletion or mutation of ANKRD11.

KBG syndrome, due to ANKRD11 alteration is characterized by developmental delay, short stature, dysmorphic facial features, and skeletal anomalies. We report a clinical and molecular study of 39 patients affected by KBG syndrome. Among them, 19 were diagnosed after the detection of a 16q24.3 deletion encompassing the ANKRD11 gene by array CGH. In the 20 remaining patients, the clinical suspicion was confirmed by the identification of an ANKRD11 mutation by direct sequencing. We present arguments to modulate the previously reported diagnostic criteria. Macrodontia should no longer be considered a mandatory feature. KBG syndrome is compatible with autonomous life in adulthood. Autism is less frequent than previously reported. We also describe new clinical findings with a potential impact on the follow-up of patients, such as precocious puberty and a case of malignancy. Most deletions remove the 5'end or the entire coding region but never extend toward 16q telomere suggesting that distal 16q deletion could be lethal. Although ANKRD11 appears to be a major gene associated with intellectual disability, KBG syndrome remains under-diagnosed. NGS-based approaches for sequencing will improve the detection of point mutations in this gene. Broad knowledge of the clinical phenotype is essential for a correct interpretation of the molecular results. © 2016 Wiley Periodicals, Inc.

A de novo 17q21.2 duplication in a boy with developmental delay and dysmorphic features.

We report a boy with severe developmental delay, microcephaly and characteristic facial dysmorphism consisting in round face, hypertelorism, upslanted palpebral fissures, small nose, large mouth, micrognathia, sparse hair and eyelashes. Array-CGH revealed a de novo duplication of 103 kb within 17q21.2 not reported to date. The duplication includes 8 genes: DHX58, KAT2A, HSPB9, RAB5C, KCNH4, HCRT, GHDC and STAT5B. Three genes (KATA2, KCNH4, and STAT5B) may contribute to intellectual deficiency. Further observations will be necessary to confirm the specificity of the facial Gestalt.