Heterozygous Mutation In Intron Research Articles

Clinical and genetic study of 20 patients from China with Cornelia de Lange syndrome

BackgroundCornelia de Lange syndrome (CdLS) is a rare congenital syndrome with no racial difference. The objective of this study is to report the clinical characteristics and genetic study of 20 CdLS cases from China.MethodsThis is an observational study. Suspected patients were referred for further confirmation, clinical treatment, and genetic testing under voluntary condition. Demographic data and family history, data of clinical manifestations including facial dysmorphism and developmental delay of each patient were collected. Chromosomal analysis and NIPBL/SMC1A/SMC3 gene mutational analysis were carried out by PCR, reverse transcription PCR direct sequencing in the probands, and SNP array to detect the genome-wide copy number variations.ResultsTwenty CdLS cases from China were included in this study. Facial dysmorphisms, feeding difficulties, and developmental delay were the major clinical manifestations. Seven patients underwent gene mutation tests. Both the SMC1A and SMC3 gene mutation tests were negative in all. A heterozygous mutation in exon 20 of the NIPBL gene in proband 2, and a heterozygous mutation in intron 38 of the NIPBL gene in proband 3 were found in 1 patient, and RT-PCR revealed a splicing mutation in exon 38, generating both normal transcript and an aberrant alternatively spliced transcript with exon 38 deletion.ConclusionsClinical manifestations of CdLS patients from China are similar to those in the other countries. Heterozygous mutations of NIPBL gene were found.

WAGNER syndrome: anatomic, functional and genetic characterization of a Portuguese family.

To report the clinical (anatomic and functional) and genetic findings of Wagner Syndrome (WS) in a Portuguese family. Nine members of the family agreed to be examined. All had complete clinical eye examinations. The proband and selected patients underwent color fundus photography, spectral domain optical coherence tomography (SD-OCT), automatic static white-on-white computerized perimetry, and electrophysiology assessment (flash ERG, multifocal(mf) ERG and dark adaptometry). A pedigree was constructed based on interviews with known affected subjects. Genomic DNA samples derived from venous blood were collected from all affected family members examined. Twenty-eight family members are affected. This family has the typical features of Wagner Syndrome, namely an empty vitreous cavity with veils, mild myopia and cataract. Four examined patients underwent vitreoretinal surgery due to abnormal peripheral vitreoretinal adhesions with peripheral retinal traction (n=3). Retinal detachment was observed in 5 of the examined subjects. Four of them occurred between the ages of 5 and 15years. Chorioretinal atrophy is also a frequent finding which results in moderate to severe visual field and advanced rod-cone dystrophy from younger ages, also confirmed by absence of scotopic function on dark adaptation. The macular dysfunction on mfERG was profound and of early onset. A heterozygous mutation in intron 7 of the VCAN gene (c.4004-1G>A) was found. We described a rare autosomal dominant vitreoretinopathy with near complete penetrance in a Portuguese family. Abnormal peripheral vitreoretinal adhesions, retinal detachment and chorioretinal atrophy are present in most of the examined individuals at young ages. Early onset of advanced visual field and electrophysiologic abnormalities were observed in this family. We also added relevant information to the literature by reporting our experience in surgical management of Wagner Syndrome patients with, and at risk of, retinal detachment.

A novel COL11A1 mutation affecting splicing in a patient with Stickler syndrome.

Stickler syndrome is a clinically and genetically heterogeneous collagenopathy characterized by ocular, auditory, skeletal and orofacial abnormalities, commonly occurring as an autosomal dominant trait. We conducted target resequencing to analyze candidate genes associated with known clinical phenotypes from a 4-year-old girl with Stickler syndrome. We detected a novel heterozygous intronic mutation (NM_001854.3:c.3168+5G>A) in COL11A1 that may impair splicing, which was suggested by in silico prediction and a minigene assay.

Pseudohypoparathyroidism Type Ia-Clinical Case with a Novel Mutation of GNAS1 Gene

Pseudohypoparathyroidism (PHP) is a rare autosomal dominant disorder resulting from loss of function mutations in the GNAS gene. Several forms of PHP are noted. PHP type 1a occurs most commonly and is characterized by physical features termed Albright’s Hereditary Osteodystrophy (AHO), a constellation of physical features which may include short stature, obesity, round facies, heterotopic ossification, brachydactyly and mental retardation, and increased levels of parathyroid hormone (PTH) due to the end organ hormone resistance to its action. Here we report a new GNAS mutation in a 3.5 years old African American female patient with a history of round facies, developmental delays, obesity and seizure disorder; she was admitted for apneic episode and noted to have prolonged QTc interval on cardiac monitor. A lab evaluation showed severe hypocalcaemia, hyperphosphatemia, high PTH with normal magnesium and alkaline phosphatase levels. She also had slightly elevated Thyroid Stimulating Hormone (TSH) levels indicative of type 1 a PHP where resistance to multiple Gs protein-coupled hormones (e.g. PTH, TSH, Luteinizing Hormone (LH), Follicular Stimulating Hormone (FSH), and Growth Hormone Releasing Hormone (GHRH)) is present. Full genomic DNA sequencing of the exons and adjacent intronic regions of the GNAS gene revealed a novel heterozygous mutation in intron 7, c.585+1G>A, in both the patient and her mother.

Recurrence of a dysgerminoma in Frasier syndrome

FS is an inherited disease characterized by male pseudohermaphroditism and glomerular involvement leading to end-stage renal disease during adolescence or early adulthood (J Pediatr 1964:64:740). The FS phenotype in 46,XY patients consists of female external genitalia, gonadal dysgenesis, high risk of gonadoblastoma, and development of renal failure in the second decade of life. FS is caused by heterozygous mutation in intron 9 of the WT1 leading to a change in splicing that results in loss of three amino acids (+KTS isoform), thus disrupting the normal ratio of the +KTS/-KTS isoforms that is critical for proper gonadal and renal development (Nat Genet 1997:17:467; Hum Mol Genet 1998:7:709). We report on a patient followed for FS revealed by acute peritoneal syndrome because of ovarian dysgerminoma. Therapeutic options had led to an unusual course with recurrent neoplastic disease after renal transplantation.

Aberrant splicing of the milk fat globule‐EGF factor 8 (MFG‐E8) gene in human systemic lupus erythematosus

Milk fat globule-EGF factor 8 (MFG-E8) promotes the phagocytosis of apoptotic cells by serving as a bridging molecule between apoptotic cells and phagocytes. Many apoptotic cells are left unengulfed in the germinal centers of the spleen of MFG-E8(-/-) mice, which develop a human systemic lupus erythematosus (SLE)-like autoimmune disease. Here, we analyzed the MFG-E8 gene in human SLE patients, and found in two out of 322 female patients a heterozygous intronic mutation, which caused a cryptic exon from intron 6 to be included in the transcript. The cryptic exon contained a premature termination codon, generating a C-terminally truncated MFG-E8 protein. The mutant MFG-E8 was aberrantly glycosylated and sialylated, but bound to phosphatidylserine and enhanced the phagocytosis of apoptotic cells. When intravenously injected into mice, the mutant MFG-E8 was sustained longer in the blood circulation than wild-type MFG-E8. Repeated administrations of the mutant MFG-E8 protein induced the production of autoantibodies, such as anti-cardiolipin and anti-nuclear antibodies, at a lower dose than that required for the wild-type protein. These results suggested that the intronic mutation in the human MFG-E8 gene can lead to the development of SLE.

Frequent genetic alterations and reduced expression of the Axin1 gene in oral squamous cell carcinoma: Involvement in tumor progression and metastasis

The aims of this study were to analyze the genetic alterations and expression levels of the Axin1 gene in oral squamous cell carcinoma (OSCC), to evaluate its clinical importance and to clarify whether the Axin1 gene is involved in the pathogenesis of OSCC. Mutation analysis of the Axin1 gene was performed by denaturing high performance liquid chromatography (DHPLC) and DNA sequencing in 44 OSCC samples. Meanwhile, Axin1 protein expression was investigated by immunohistochemistry in these samples. Aberrant profiles were detected by DHPLC screening in 26 different OSCC cases. After sequencing analysis, four mutations and five polymorphisms were identified. One case of poorly differentiated OSCC with metastasis contained two mutations: one revealed a T>G substitution at nucleotide 324 in exon 1, resulting in a glycine to stop codon substitution at amino acid residue 108; the other revealed an A>G heterozygous mutation in intron 7, located very near to exon 8. In another two patients with moderately differentiated OSCC and metastasis, a G>T heterozygous mutation at codon 488 in exon 5 and a C>G substitution at the intron 5+26 position was detected, respectively. Five polymorphisms were all frequent and localized at positions of codon 254 (GAT--> GAC), codon 429 (GTC-->ATC), codon 525 (GAC-->GAT), codon 609 (GCT--> GCC), and intron 4+17 (G>A), with a frequency of 39%, 8%, 6%, 13% and 9%, respectively. Immunoreactivity for Axin1 was strongly positive in normal stratified squamous epithelium but significantly reduced expression of Axin1 was shown in most of the 44 tumor specimens (35/44), especially in poorly differentiated tumors with metastasis. These results suggest that mutational inactivation and reduced expression of the Axin1 gene may play a pivotal role in OSCC carcinogenesis and metastasis.