We describe two unrelated patients, a 12-yr-old female and a 6-yr-old male, with congenital contractures and severe congenital muscular atrophy. Exome and genome sequencing of the probands and their ...unaffected parents revealed that they have the same de novo deletion in
(c.1636_1638delAAT). The variant, which has never been reported, results in an in-frame 3-bp deletion and is predicted to cause loss of an evolutionarily conserved asparagine residue at position 546 in the protein. Missense mutations in
cause autosomal dominant spinal muscular atrophy, lower-extremity predominant 2 (SMALED2), a disease characterized by muscle weakness and arthrogryposis of early onset and slow progression. The p.Asn546del clusters with four pathogenic missense variants in a region that likely binds molecular motor KIF5A. Protein modeling suggests that removing the highly conserved asparagine residue alters BICD2 protein structure. Our findings support a broader phenotypic spectrum of
mutations that may include severe manifestations such as cerebral atrophy, seizures, dysmorphic facial features, and profound muscular atrophy.
We describe two unrelated patients, a 12-yr-old female and a 6-yr-old male, with congenital contractures and severe congenital muscular atrophy. Exome and genome sequencing of the probands and their ...unaffected parents revealed that they have the same de novo deletion in BICD2 (c.1636_1638delAAT). The variant, which has never been reported, results in an in-frame 3-bp deletion and is predicted to cause loss of an evolutionarily conserved asparagine residue at position 546 in the protein. Missense mutations in BICD2 cause autosomal dominant spinal muscular atrophy, lower-extremity predominant 2 (SMALED2), a disease characterized by muscle weakness and arthrogryposis of early onset and slow progression. The p.Asn546del clusters with four pathogenic missense variants in a region that likely binds molecular motor KIF5A. Protein modeling suggests that removing the highly conserved asparagine residue alters BICD2 protein structure. Our findings support a broader phenotypic spectrum of BICD2 mutations that may include severe manifestations such as cerebral atrophy, seizures, dysmorphic facial features, and profound muscular atrophy.
Objectives To determine the mechanism for the 46,XX/46,XY karyotype observed in a patient with an ovotesticular disorder of sexual development (ie, true hermaphroditism). Methods Cytogenetic, ...molecular cytogenetic, and molecular DNA analyses were performed on the blood, skin, and left and right gonadal tissue from 2 surgical procedures. The results of these studies were used to determine whether the ovotesticular disorder of sexual development resulted from mosaicism or tetragametic chimerism. Results Cytogenetic and molecular analyses revealed a mixture of 46,XX and 46,XY cells in most tissues. DNA analysis from the gonadal tissues from surgeries 1 and 2 was performed. Highly polymorphic loci from 12 different chromosomes were examined for the presence of ≥1 paternal or maternal alleles. Three loci were highly informative: D14S544 (14q32.2), DS14S583 (14q21.3), and SE33 (6q14). Each demonstrated the presence of 2 paternal and 2 maternal alleles, indicating that the ovotesticular disorder of sexual development resulted from tetragametic chimerism. Conclusions Based on the findings of the cytogenetic, molecular cytogenetic, and DNA analyses of the polymorphic markers from several different loci, it was confirmed that the patient had tetragametic chimerism. This case has assisted in increasing our knowledge of the possible mechanisms causing this rare and complex disorder.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Routine clinical application of whole exome sequencing remains challenging due to difficulties in variant interpretation, large dataset management, and workflow integration. We describe a tool named ...ClinLabGeneticist to implement a workflow in clinical laboratories for management of variant assessment in genetic testing and disease diagnosis. We established an extensive variant annotation data source for the identification of pathogenic variants. A dashboard was deployed to aid a multi-step, hierarchical review process leading to final clinical decisions on genetic variant assessment. In addition, a central database was built to archive all of the genetic testing data, notes, and comments throughout the review process, variant validation data by Sanger sequencing as well as the final clinical reports for future reference. The entire workflow including data entry, distribution of work assignments, variant evaluation and review, selection of variants for validation, report generation, and communications between various personnel is integrated into a single data management platform. Three case studies are presented to illustrate the utility of ClinLabGeneticist. ClinLabGeneticist is freely available to academia at http://rongchenlab.org/software/clinlabgeneticist .
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Abstract
Williams syndrome (WS) is a complex genomic disorder entailing distinctive facial dysmorphism, cardiovascular abnormalities, intellectual disabilities, unusual behavioral features, and a ...specific cognitive profile with considerable variability. Additional symptoms include endocrine abnormalities, renal anomalies and connective tissue disorders. We report a monozygotic twin patient with WS who presented with multicystic kidneys in the newborn period, and, in addition to the typical WS deletion at 7q11.23, was found to have a de novo 1.7 Mb deletion in the 17q12 region on microarray comparative genomic hybridization. The co-twin was selectively terminated at 23 wk of gestation after being diagnosed with bilateral multicystic dysplastic kidneys and anhydramnios. Review of the literature shows that deletion of chromosome 17q12, encompassing hepatocyte nuclear factor 1beta gene, is associated with cystic renal disease and is the first recurrent genomic deletion associated with maturity onset diabetes of the young. In addition, reports of female reproductive tract malformations and patients with neurocognitive or psychiatric phenotypes have recently been described. This review of the literature summarizes 47 other cases involving 17q12 deletions with wide variability in phenotype, possibly suggesting a contiguous gene syndrome. It is likely that the additional 17q12 deletion has played a role in modifying the phenotype in our patient. This case highlights the importance of using array comparative genomic hybridization in the clinical setting to uncover the etiology of atypical findings in individuals with known microdeletion syndromes.
Abstract Characteristic features of the 12q14 microdeletion syndrome include low birth weight, failure to thrive, short stature, learning disabilities and Buschke–Ollendorff lesions in bone and skin. ...This report on two additional patients with this microdeletion syndrome emphasizes the rather constant and uniform phenotype encountered in this disorder and refines the critical region to a 2.61 Mb interval on 12q14.3, encompassing 10 RefSeq genes. We have previously shown that LEMD3 haploinsufficiency is responsible for the Buschke–Ollendorff lesions and now provide strong evidence that a heterozygous deletion of HMGA2 is causing the growth failure observed in this disorder. The identification of an intragenic HMGA2 deletion in a boy with proportionate short stature and the cosegregation of this deletion with reduced adult height in the extended family of the boy further underscore the role of HMGA2 in regulating human linear growth.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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