[Identification of VEGFR3 gene mutation in a Chinese family with autosomal dominant primary congenital lymphoedema].

OBJECTIVE: To identify the disease-causing gene in a four-generation Chinese family with 9 members affected with primary congenital lymphoedema (PCL, also known as Milroy disease). METHODS: Linkage analysis was performed with a few microsatellite markers flanking the candidate genetic loci for PCL, including 3 known genes associated with autosomal dominant PCL. For mutation analysis, VEGFR3 gene was sequenced with DNA from the proband. Direct DNA sequencing of exon 25 of the VEGFR3 gene was performed in all family members. RESULTS: The disease gene in the family was mapped to chromosome 5q35.3 with a maximum Lod score of 2.07. Direct DNA sequencing of VEGFR3 gene revealed a heterozygous C to T transition at nucleotide 3341, resulting in p.Pro1114Leu mutation. The p.Pro1114Leu mutation co-segregated with all affected individuals in the family. CONCLUSION: This study identified a C3341T (p.Pro1114Leu) mutation in the VEGFR3 gene in a Chinese family with PCL, provided evidence that VEGFR3 mutation can cause PCL in Chinese.

[c.359T>C mutation of the MYH14 gene in two autosomal dominant non-syndromic hearing impairment families with common ancestor].

OBJECTIVE: To identify the gene mutation for two Chinese families with autosomal dominant non-syndromic hearing impairment(NSHI). METHODS: Two NSHI pedigrees with common ancestor were identified by clinical examination and family investigation. Linkage analysis was performed for all known NSHI loci, and all exons and exon-intron boundaries of the non-muscle myosin heavy chain 14 (MYH14) gene were amplified by PCR and sequenced. RESULTS: The disease-causing gene of these 2 pedigrees was fine mapped to the DFNA4 locus on 19q13.33. A heterozygous transition of c. 359T>C (p.S120L) in MYH14 gene was identified. The mutation was detected in all patients but not in normal members in the two families. CONCLUSION: It is the first report that mutation in MYH14 gene can cause dominant non-syndromic hearing impairment in Asian population, suggesting that MYH14 gene can be a disease-causing gene of Chinese patients with hearing impairment.

[Analysis of PAX6 gene in a Chinese family with congenital aniridia].

OBJECTIVE: To explore the pathogenic mutation in a Chinese family with congenital aniridia. METHODS: It is a case-control study. All 21 members of the family underwent a comprehensive ophthalmic examination and family line investigation. Mononuclear cell was isolated from peripheral blood and genomic DNA was prepared by genomic DNA purification kit. All fourteen exons of the PAX6 gene were amplified by polymerase chain reaction (PCR) from proband's genomic DNA. PCR products of each exon were analyzed by direct sequencing. RESULTS: A nonsense mutation (Q310X) in exon 11 of PAX6 gene was detected by sequencing analysis in the proband III2. This mutation cause the 301st amino acids codon switch from CAA to TAA and the codogenic amino acids altered from glutamine glutaminic acid to strong terminal codon. This mutation is also detected in all 11 patients of this family, but not present in the unaffected members in this family. CONCLUSION: The premature translation termination of PAX6 gene caused by a nonsense mutation of Q310X should be responsible for congenital aniridia in this Chinese family.

A novel genetic locus for familial febrile seizures and epilepsy on chromosome 3q26.2-q26.33.

Febrile seizures (FS) are common in children, and the incidence is 2-5% before the age of 5 years. A four-generation Chinese family with autosomal dominant febrile seizure and epilepsy was studied by genome-wide linkage analysis. Significant linkage was identified with markers on chromosome 3q26.2-26.33 with a maximum pairwise LOD score of >3.00. Fine mapping defined the new genetic locus within a 10.7-Mb region between markers D3S3656 and D3S1232. A maximum multipoint LOD score of 5.27 was detected at marker D3S1565. A previously reported CLCN2 gene for epilepsy was excluded as the disease-causing gene in the family by mutational analysis of all exons and exon-intron boundaries of CLCN2 and by haplotype analysis. Mutation analysis of KCNMB2 and KCNMB3, which were two potassium-channel genes in this linkage region, did not reveal a disease causing mutation. Our results identified another novel locus on chromosome 3q26.2-26.33, and future studies of the candidate genes at the locus will identify a new gene for combined FS and idiopathic epilepsies.

[NF1 mutation analysis in a Chinese family with neuro- fibromatosis type].

A Chinese family affected with autosomal dominant disorder-neurofibromatosis type I was identified in this study. Linkage analysis was performed, and DNA sequencing for whole coding region of NF1 was carried out to identify the disease-causing mutation. The disease gene of the Chinese NF1 family was linked to NF1 locus, and a nonsense mutation, G1336X in the NF1 gene was identified. This mutation truncates the NF1 protein by 1 483 amino acid residues at the C-terminus, and is co-segregate with all the patients, but not present in unaffected individuals in the family. The present study demonstrated that G1336X mutation in the NF1 gene cause Neurofibromatosis type I in the family. To our knowledge, this mutation is firstly reported in Chinese population.

[Genetic analysis of GJB2 in a Chinese family with nonsyndromic hearing impairment].

Nonsyndromic neurosensory hearing impairment (NSHI) is the most common human sensory disorder. Approximately one in a thousand children is born with prelingual hearing loss. Mutations of the GJB2 gene, which encodes Connexin 26, are the most common cause of hereditary NSHI in many ethnic populations, and are responsible for 50% of cases of autosomal recessive NSHI. In this study, we recruited a complex NSHI pedigree from Jiangsu province of China. Linkage analysis of microsatellite markers flanking all known arNSHI genes linked the causative gene in the family to the polymorphic macrosatellite marker D13S175. Direct DNA sequencing of the whole coding region of GJB2 revealed that a common homozygous mutation 235delC was responsible for most of the affected members in the NSHI family.

A biphasic pattern of gene expression during mouse retina development.

BACKGROUND: Between embryonic day 12 and postnatal day 21, six major neuronal and one glia cell type are generated from multipotential progenitors in a characteristic sequence during mouse retina development. We investigated expression patterns of retina transcripts during the major embryonic and postnatal developmental stages to provide a systematic view of normal mouse retina development, RESULTS: A tissue-specific cDNA microarray was generated using a set of sequence non-redundant EST clones collected from mouse retina. Eleven stages of mouse retina, from embryonic day 12.5 (El2.5) to postnatal day 21 (PN21), were collected for RNA isolation. Non-amplified RNAs were labeled for microarray experiments and three sets of data were analyzed for significance, hierarchical relationships, and functional clustering. Six individual gene expression clusters were identified based on expression patterns of transcripts through retina development. Two developmental phases were clearly divided with postnatal day 5 (PN5) as a separate cluster. Among 4,180 transcripts that changed significantly during development, approximately 2/3 of the genes were expressed at high levels up until PN5 and then declined whereas the other 1/3 of the genes increased expression from PN5 and remained at the higher levels until at least PN21. Less than 1% of the genes observed showed a peak of expression between the two phases. Among the later increased population, only about 40% genes are correlated with rod photoreceptors, indicating that multiple cell types contributed to gene expression in this phase. Within the same functional classes, however, different gene populations were expressed in distinct developmental phases. A correlation coefficient analysis of gene expression during retina development between previous SAGE studies and this study was also carried out. CONCLUSION: This study provides a complementary genome-wide view of common gene dynamics and a broad molecular classification of mouse retina development. Different genes in the same functional clusters are expressed in the different developmental stages, suggesting that cells might change gene expression profiles from differentiation to maturation stages. We propose that large-scale changes in gene regulation during development are necessary for the final maturation and function of the retina.

Genetic analysis of a family with 46,XY "female" associated with infertility.

Genetic analysis of a family with 46,XY "female" associated with infertility was performed using the conventional G-banding and gene mutation screening. The karyotypes of the two female patients were 46,XY and those of their parents were normal. The mutation screenings in sex-determining region Y (SRY) gene and androgen receptor (AR) gene were carried out. No mutation has been found in the whole coding sequence of SRY gene. The mutation of codon 840 CGT (arginine) to CAT (histidine) of AR gene led to the infertility in the patients. The patients showed androgen insensitivity. The clinical phenotype of theirs presented more deleteriously than and different from the one reported before, though they had the same mutation of codon 840 CGT (arginine) to CAT (histidine) of AR gene, which was very different from the mutation of 840 CGT (arginine) to TGT (cysteine) at the same codon.

Mutation p.Arg954Trp of KIF21A causes congenital fibrosis of the extraocular muscles in a Chinese family.

Congenital fibrosis of the extraocular muscles type 1 (CFEOM1) is an autosomal dominant strabismus disorder associated with defects of the oculomotor nerve. In this study, we identified a Chinese family with CFEOMI for four generations. Linkage analysis mapped the causative gene of the family to 12q with a Lod score 2.1 for polymorphic marker D12S85, where KIF21A is located. Direct DNA sequence analysis identified a 2860C-->T change in exon 21, resulting in a tryptophan substitution for arginine in codon 954 of KIF21A. SSCP (single-stranded conformational polymorphism) analysis showed that mutation p.Arg954Trp of KIF21A co-segregated with the affected members, but was absent in the unaffected individuals in the family and 150 normal controls. Our results indicate that mutation p.Arg954Trp of the KIF21A is the genetic basis of the Chinese family with CFEOM1.

Two novel missense mutations of GATA4 gene in Chinese patients with sporadic congenital heart defects.

OBJECTIVE: To identify mutations in GATA4 gene in Chinese patients with sporadic congenital heart defects (CHD). METHODS: Single stranded conformation polymorphism (SSCP) analysis was performed to screen for mutations in all six exons and exon-intron boundaries of GATA4 in 31 individuals with CHD. Direct DNA sequencing was used to identify the specific mutations. RESULTS: Two novel missense mutations, V267M in exon 4, V380M in exon 6, and one polymorphism in intron 6 of GATA4 were identified. CONCLUSION: The above identified two novel GATA4 mutations associated with CHD in Chinese patients. This suggests that the transcription factor GATA4 may play an important role in cardiogenesis.

The G401D mutation of OPA1 causes autosomal dominant optic atrophy and hearing loss in a Chinese family.

OBJECTIVE: To describe the clinical and genetic characteristics of a Chinese family affected with optic atrophy 1 (OPA1). METHODS: Linkage analysis and DNA sequencing as well as PCR/restriction fragment length polymorphism (RFLP) analysis were performed to identify the disease-causing mutation. RESULTS: A missense mutation, G401D in the OPA1 gene was identified, and the patients demonstrate inherited syndrome of optic atrophy and hearing loss. CONCLUSION: The present study demonstrates that a mutation in the OPA1 gene can cause optic atrophy in Chinese patients, and supports the notion that OPA1 mutation may lead to OPA1 combined with hearing loss.

[Mutation of Thr704Met in SCN 4A causes normoKPP in a Chinese family].

Familial periodic paralysis (PP) is an autosomal dominant disorder characterized by episodic attacks of paralysis with different severity. We recruited a normoKPP family in Hubei China and evaluated genetic variations responsible for the disease. Linkage analysis was performed through microsatellite markers. Markers flanking SCN4A showed linkage evidence in the family. Sequencing of SCN4A exons revealed a substitution C2111T leading to the mutation Thr704Met in all affected family members, and was not observed in either unaffected members of the family or 100 unrelated individuals (controls). This mutation should be responsible for normoKPP in this family.

Comprehensive in silico functional specification of mouse retina transcripts.

BACKGROUND: The retina is a well-defined portion of the central nervous system (CNS) that has been used as a model for CNS development and function studies. The full specification of transcripts in an individual tissue or cell type, like retina, can greatly aid the understanding of the control of cell differentiation and cell function. In this study, we have integrated computational bioinformatics and microarray experimental approaches to classify the tissue specificity and developmental distribution of mouse retina transcripts. RESULTS: We have classified a set of retina-specific genes using sequence-based screening integrated with computational and retina tissue-specific microarray approaches. 33,737 non-redundant sequences were identified as retina transcript clusters (RTCs) from more than 81,000 mouse retina ESTs. We estimate that about 19,000 to 20,000 genes might express in mouse retina from embryonic to adult stages. 39.1% of the RTCs are not covered by 60,770 RIKEN full-length cDNAs. Through comparison with 2 million mouse ESTs, spectra of neural, retinal, late-generated retinal, and photoreceptor -enriched RTCs have been generated. More than 70% of these RTCs have data from biological experiments confirming their tissue-specific expression pattern. The highest-grade retina-enriched pool covered almost all the known genes encoding proteins involved in photo-transduction. CONCLUSION: This study provides a comprehensive mouse retina transcript profile for further gene discovery in retina and suggests that tissue-specific transcripts contribute substantially to the whole transcriptome.

[Advances in the studies on the molecular and genetic aspects of epilepsy].

Epilepsy is one of the most common and debilitating neurological diseases that affects more than 40 million people worldwide. Genetic factors contribute to the pathogenesis of epilepsy. Molecular genetic studies have identified 15 disease-causing genes for epilepsy. The majority of the genes encode ion channels, including voltage-gated potassium channels KCNQ2 and KCNQ3, sodium channels SCN1A, SCN2A, and SCN1B, chloride channels CLCN2, and ligand-gated ion channels CHRNA4, CHRNB2, GABRG2, and GABRA1. Interestingly, non-ion channel genes have also been identified as epilepsy genes, and these genes include G-protein-coupled receptor MASS1/VLGR1, GM3 synthase, and proteins with unknown functions such as LGI1, NHLRC1, and EFHC1. These studies make genetic testing possible in some patients, and further characterization of the identified epilepsy genes may lead to the development of new drugs and new treatments for patients with epilepsy.

Comparison of gene expression during in vivo and in vitro postnatal retina development.

UNLABELLED: Retina explants are widely used as a model of neural development. To define the molecular basis of differences between the development of retina in vivo and in vitro during the early postnatal period, we carried out a series of microarray comparisons using mouse retinas. About 75% of 8,880 expressed genes from retina explants kept the same expression volume and pattern as the retina in vivo. Fewer than 6% of the total gene population was changed at two consecutive time points, and only about 1% genes showed more than a threefold change at any time point studied. Functional Gene Ontology (GO) mapping for both changed and unchanged genes showed similar distribution patterns, except that more genes were changed in the GO clusters of response to stimuli and carbohydrate metabolism. Three distinct expression patterns of genes preferentially expressed in rod photoreceptors were observed in the retina explants. Some genes showed a lag in increased expression, some showed no change, and some continued to have a reduced level of expression. An early downregulation of cyclin D1 in the explanted retina might explain the reduction in numbers of precursors in explanted retina and suggests that external factors are required for maintenance of cyclin D1. The global view of gene profiles presented in this study will help define the molecular changes in retina explants over time and will provide criteria to define future changes that improve this model system. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s12177-008-9009-z) contains supplementary material, which is available to authorized users.

STAT3 activation protects retinal ganglion cell layer neurons in response to stress.

STAT3 is a major signaling molecule for many neurotrophic factors but its direct role in the protection of neurons in response to stress has not been addressed. We have studied the role of STAT3 in protecting retinal neurons from damage induced by ischemia/reperfusion and glutamate excitotoxicity by using adenovirus constructs to introduce active, normal or inactive STAT3 into retinal ganglion cells in culture and cells of the ganglion cell layer in the intact retina. Transient ischemia/reperfusion was induced in adult CD1 mice by elevating the intraocular pressure to the equivalent of 120mmHg for 60min, followed by a return to normal pressure. The levels, activation and distribution of STAT3 protein were evaluated by Western blot and immunocytochemistry. A transient peak of STAT3 activation was seen at 24h post ischemia and a strong increase in STAT3 protein levels 24h later. The increase in levels of STAT3 was detected in both ganglion cell bodies and processes in the plexiform layers by immunocytochemistry. The time course of STAT3 increase was slower than the time course of ganglion cell death as measured by TUNEL assay. Intravitreal injection of NMDA led to peak increases in activated STAT3 and STAT3 at 12 and 24h post insult respectively. Purified RGCs were infected with recombinant wild-type STAT3, constitutively active and dominant negative forms of STAT3 adenoviruses or control empty virus and then treated with glutamate. Surviving infected cells were counted 24 and 48h later. Infection with constitutively active STAT3 gave substantial protection when compared to the other constructs. Similarly, intravitreal injection of constitutively active STAT3 adenovirus one day before ischemia-reperfusion resulted in a decreased neural cell death in the ganglion cell layer compared with GFP adenovirus control. Our results suggest that persistent activation of STAT3 by neurotrophic factors provides strong neuroprotection and will be an effective strategy in a number of chronic retinal diseases.

STAT3 activation in response to growth factors or cytokines participates in retina precursor proliferation.

Growth factors and cytokines play an important role in the development of central nervous systems including neurons of the retina. However, the molecular pathways that trigger cell growth remain unclear in neuronal precursors. In the present studies, we used a retinal explant culture system to investigate the response of signal transducer and activator of transcription factors (STATs) to extrinsic factors during mouse retinal development. Retinas from embryonic and neonatal stages showed that STAT3 but not STAT1 was activated in response to ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), fibroblast growth factor-1 (FGF1), fibroblast growth factor-2 (FGF2), epidermal growth factor (EGF), interferon-alpha (IFN-alpha) and interferon-gamma (IFN-gamma) in distinct patterns. STAT3 activation was detected in the outermost retina layer in response to CNTF, LIF, FGF1, and IFN-alpha 24 hr after stimulation in postnatal day 1 (PN1) explants, but not FGF2, EGF, IFN-gamma, and retinoic acid (RA). Cytokine stimulation increased the number of cells incorporating BrdU and the labelled cells co-localized with phosphorylated STAT3, indicating that STAT3 may play an essential role in coupling extrinsic factors to retina precursor cell (RPC) proliferation. Furthermore, persistent expression of two neural precursor markers, Hes1 and Otx2 was detected in outer retinal layers and correlated with STAT3 activation by CNTF, suggesting that STAT3 activation may play a critical role in stimulating mitotic precursors. These results strongly support a model that STAT3-mediated signalling regulates precursor populations during mouse retina development.

Cardiomyocyte-restricted knockout of STAT3 results in higher sensitivity to inflammation, cardiac fibrosis, and heart failure with advanced age.

Cytokines and inflammation have been implicated in the pathogenesis of heart failure. For example, IL-6 family cytokines and the gp130 receptor play important roles in cardiac myocyte survival and hypertrophy. Signal transducer and activator of transcription 3 (STAT3) is a major signaling protein that is activated through gp130. We have created mice with a cardiomyocyte-restricted deletion of STAT3. As measured by serial echocardiograms, mice with cardiac specific deletion of STAT3 are significantly more susceptible to cardiac injury after doxorubicin treatment than age-matched controls. Intriguingly, STAT3 appears to have a critical role in protection of inflammation-induced heart damage. STAT3-deficient mice treated with lipopolysaccharide demonstrated significantly more apoptosis than their WT counterparts. At the cellular level, cardiomyocytes with STAT3 deleted secrete significantly more tumor necrosis factor in response to lipopolysaccharide than those with WT STAT3. Furthermore, histologic examination of the cardiomyocyte-restricted STAT3-deficient mice reveals a dramatic increase in cardiac fibrosis in aged mice. Although no overt signs of heart failure are present in young STAT3-deficient mice, they spontaneously develop heart dysfunction with advancing age. These results indicate the crucial functions of STAT3 in cardiomyocyte resistance to inflammation and other acute injury and in pathogenesis of age-related heart failure.