NSHL is characterized by a high clinical and genetic heterogeneity with approximately 115 genes and 170 loci identified to date. Because of this genetic heterogeneity, current genetic tests fail to ...provide a diagnosis for the vast majority of cases, suggesting that many novel HL genes and mutations remain to be discovered (1). ...the bioinformatic data predictions about the mutation effects, as reported by Annunen S et al(6) and Miyagawa M et al(10), confirm the possible causative effect. ...the heterogeneity of the hearing loss segregating in the family further confirm ourfindings. CONCLUSION The mutation identified represents, to the best of our knowledge, a third world case of mutation in COL11 Al associated with autosomal dominant NSHL Moreover, taking into consideration the case of this family, we would like to highlight the variability of the clinical features (as expected in the autosomal dominant conditions), ranging from prelingual severe hearing loss in the proband and his twin to postlingual moderate hearing loss in the sister, father, and grandmother. ...in families with autosomal dominant transmission, it is important to consider COL 11A1 gene in the genetic workup of the NSHL with prelingual onset.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Massive parallel sequencing of 70 genes in a girl with a suspicion of chromatinopathy detected the (NM_015443.4:)c.985_986delTT variant in exon 2 of KANSL1, which led to a diagnostic consideration of ...Koolen De Vries syndrome. The same variant was present in the healthy mother, consistent with either incomplete penetrance or variant mismapping. A network of second opinion was implemented among clinical geneticists first, and a diagnosis of Koolen De Vries syndrome was considered unlikely. By MLPA, a duplication spanning exons 1-3 of KANSL1 was detected in both the mother and the daughter. On cDNA sequencing, biallelic wild type mRNA was observed. We concluded that the variant affects the noncoding duplicated gene region in our family, and we finally classified it as benign. Parallel wide genomic sequencing is increasingly the first genetic investigation in individuals with intellectual disability. The c.985_986delTT variant in KANSL1 was described both in individuals with typical KdVS and in a limited number of healthy subjects. This report highlights the role of clinical genetics to correctly classify variants and to define proper clinical and diagnostic correlations. Keywords: KANSL1; variant interpretation; clinical evaluation; copy number polymorphisms
Bohring-Opitz syndrome (BOS) is a rare genetic disorder characterised by a recognisable craniofacial appearance and a typical 'BOS' posture. BOS is caused by sporadic mutations of
. However, several ...typical patients with BOS have no molecular diagnosis, suggesting clinical and genetic heterogeneity.
To expand the phenotypical spectrum of autosomal recessive variants of
, reported as causing Crisponi syndrome/cold-induced sweating syndrome type 1 (CS/CISS1)-like syndrome.
We performed whole-exome sequencing in two families with a suspected recessive mode of inheritance. We used the Matchmaker Exchange initiative to identify additional patients.
Here, we report six patients with microcephaly, facial dysmorphism, including exophthalmos, nevus flammeus of the glabella and joint contractures with a suspected BOS posture in five out of six patients. We identified autosomal recessive truncating mutations in the
gene.
encodes a BTB-kelch protein implicated in the cell cycle and in protein degradation by the ubiquitin-proteasome pathway. Recently, biallelic mutations in the
gene were reported in four families and associated with CS/CISS1, characterised by clinical features overlapping with our patients.
We have expanded the clinical spectrum of
autosomal recessive variants by describing a syndrome with features overlapping CS/CISS1 and BOS.
Unique or multiple congenital facial skin polyps are features of several rare syndromes, from the most well‐known Pai syndrome (PS), to the less recognized oculoauriculofrontonasal syndrome (OAFNS), ...encephalocraniocutaneous lipomatosis (ECCL), or Sakoda complex (SC). We set up a research project aiming to identify the molecular bases of PS. We reviewed 27 individuals presenting with a syndromic frontonasal polyp and initially referred for PS. Based on strict clinical classification criteria, we could confirm only nine (33%) typical and two (7%) atypical PS individuals. The remaining ones were either OAFNS (11/27—41%) or presenting with an overlapping syndrome (5/27—19%). Because of the phenotypic overlap between these entities, OAFNS, ECCL, and SC can be either considered as differential diagnosis of PS or part of the same spectrum. Exome and/or genome sequencing from blood DNA in 12 patients and from affected tissue in one patient failed to identify any replication in candidate genes. Taken together, our data suggest that conventional approaches routinely utilized for the identification of molecular etiologies responsible for Mendelian disorders are inconclusive. Future studies on affected tissues and multiomics studies will thus be required in order to address either the contribution of mosaic or noncoding variation in these diseases.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The presence of redundant copy number variants (CNVs) in groups of patients with neurological diseases suggests that these variants could have pathogenic effect. We have collected array comparative ...genomic hybridization (CGH) data of about 2,500 patients affected by neurocognitive disorders and we observed that CNVs in 2p16.3 locus were as frequent as those in 15q11.2, being both the most frequent unbalances in our cohort of patients. Focusing to 2p16.3 region, unbalances involving NRXN1 coding region have been already associated with neuropsychiatric disorders, although with incomplete penetrance, but little is known about CNVs located proximal to the gene, in the long noncoding RNA AK127244. We found that, in our cohort of patients with neuropsychiatric disorders, the frequency of CNVs involving AK127244 was comparable to that of NRXN1 gene. Patients carrying 2p16.3 unbalances shared some common clinical characteristics regardless NRXN1 and AK127244 CNVs localization, suggesting that the AK127244 long noncoding RNA could be involved in neurocognitive disease with the same effect of NRXN1 unbalances. AK127244 as well as NRXN1 unbalances seem to have a particular influence on language development, behavior or mood, according with the topographic correlation between NRXN1 expression and prefrontal cortex functions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Genomics enables individualized diagnosis and treatment, but large challenges remain to functionally interpret rare variants. To date, only one causative variant has been described for KCNK9 ...imprinting syndrome (KIS). The genotypic and phenotypic spectrum of KIS has yet to be described and the precise mechanism of disease fully understood.
This study discovers mechanisms underlying KCNK9 imprinting syndrome (KIS) by describing 15 novel KCNK9 alterations from 47 KIS-affected individuals. We use clinical genetics and computer-assisted facial phenotyping to describe the phenotypic spectrum of KIS. We then interrogate the functional effects of the variants in the encoded TASK3 channel using sequence-based analysis, 3D molecular mechanic and dynamic protein modeling, and in vitro electrophysiological and functional methodologies.
We describe the broader genetic and phenotypic variability for KIS in a cohort of individuals identifying an additional mutational hotspot at p.Arg131 and demonstrating the common features of this neurodevelopmental disorder to include motor and speech delay, intellectual disability, early feeding difficulties, muscular hypotonia, behavioral abnormalities, and dysmorphic features. The computational protein modeling and in vitro electrophysiological studies discover variability of the impact of KCNK9 variants on TASK3 channel function identifying variants causing gain and others causing loss of conductance. The most consistent functional impact of KCNK9 genetic variants, however, was altered channel regulation.
This study extends our understanding of KIS mechanisms demonstrating its complex etiology including gain and loss of channel function and consistent loss of channel regulation. These data are rapidly applicable to diagnostic strategies, as KIS is not identifiable from clinical features alone and thus should be molecularly diagnosed. Furthermore, our data suggests unique therapeutic strategies may be needed to address the specific functional consequences of KCNK9 variation on channel function and regulation.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Rett syndrome (RTT) is an X-linked dominant neurological disorder, which appears to be the most common genetic cause of profound combined intellectual and physical disability in Caucasian females. ...This syndrome has been associated with mutations of the MECP2 gene, a transcriptional repressor of unknown target genes. We report a detailed mutational analysis of a large cohort of RTT patients from the UK and Italy. This study has permitted us to produce a hot spot map of the mutations identified. Bioinformatic analysis of the mutations, taking advantage of structural and evolutionary data, leads us to postulate the existence of a new functional domain in the MeCP2 protein, conserved among brain-specific regulatory factors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Joubert syndrome–related disorders (JSRDs) are a group of clinically and genetically heterogeneous conditions that share a midbrain-hindbrain malformation, the molar tooth sign (MTS) visible on brain ...imaging, with variable neurological, ocular, and renal manifestations. Mutations in the
CEP290 gene were recently identified in families with the MTS-related neurological features, many of which showed oculo-renal involvement typical of Senior-Löken syndrome (JSRD-SLS phenotype). Here, we performed comprehensive
CEP290-mutation analysis on two nonoverlapping cohorts of JSRD-affected patients with a proven MTS. We identified mutations in 19 of 44 patients with JSRD-SLS. The second cohort consisted of 84 patients representing the spectrum of other JSRD subtypes, with mutations identified in only two patients. The data suggest that
CEP290 mutations are frequently encountered and are largely specific to the JSRD-SLS subtype. One patient with mutation displayed complete
situs inversus, confirming the clinical and genetic overlap between JSRDs and other ciliopathies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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