Lsh, a member of the SNF2 family, is required for genome-wide methylation

Methylation patterns of the mammalian genome are thought to be crucial for development. The precise mechanisms designating specific genomic loci for methylation are not known. Targeted deletion of Lsh results in perinatal lethality with a rather normal development. We report here, however, that Lsh(-/-) mice show substantial loss of methylation throughout the genome. The hypomethylated loci comprise repetitive elements and single copy genes. This suggests that global genomic methylation is not absolutely required for normal embryogenesis. Based on the similarity of Lsh to other SNF2 chromatin remodeling proteins, it suggests that alteration of chromatin affects global methylation patterns in mice.     

Crouzon syndrome: mutations in two spliceoforms of FGFR2 and a common point mutation shared with Jackson--Weiss syndrome

Dominant mutations in the fibroblast growth factor receptor2 (FGFR2) gene have been recently identified as causes of fourphenotypically distinct craniosynostosis syndromes, includingCrouzon, Jackson—Weiss, Pfeiffer, and Apert syndromes.These data suggest that the genetics of the craniosynostosissyndromes is more complex than would be expected from theirsimple autosomal-dominant inheritance pattern. Identical mutationsin the FGFR2 gene have been reported to cause both Pfeifferand Crouzon syndrome phenotypes. We now report the finding ofa mutation in exon Illc of the FGFR2 gene in a kindred affectedwith Crouzon syndrome (C1043 to G; Ala344Gly) that is identicalto the mutation previously associated with Jackson—Weisssyndrome. We also report finding in a Crouzon kindred a mutationin the 3' end of exon Illu (formerly referred to as exon 5,exon 7, or exon U) (A878 to C; Gln289Pro) which encodes theamino terminal portion of the lg-like III domain of the FGFR2protein. This exon is common to both the FGFR2 and the KGFRspliceoforms of the FGFR2 gene, unlike all previously reportedCrouzon mutations, which have been found only in the FGFR2 spliceoform.These findings reveal further unexpected complexity in the moleculargenetics of these craniosynostosis syndromes. The data impliesthat second-site mutations in FGFR2 itself (outside of exonIllc) or in other genes may determine specific aspects of thephenotypes of craniosynostosis syndromes.     

Molecular cloning of a novel human gene (SIRP-B2) which encodes a new member of the SIRP/SHPS-1 protein family

A full-length cDNA encoding a novel protein was isolated and sequenced from a human placental cDNA library. This cDNA consists of 1735 base pairs and has a predicted open reading frame (ORF) encoding 354 amino acids. It possesses a putative signal sequence, a long extracellular domain, a transmembrane region, a short intracellular domain, and no catalytic domain, which is highly homologous to signal-regulatory protein (SIRP)-β, suggesting that it seems to be a new member of the SIRP family. Polymerase chain reaction (PCR)-based mapping with both a monochromosomal hybrid panel and radiation hybrid cell panels placed the gene to human chromosome 20p13 near the marker D20S906. Received: August 11, 2000 / Accepted: September 21, 2000     

Sensenbrenner syndrome: a new member of the hepatorenal fibrocystic family

Cranioectodermal dysplasia (CED, Sensenbrenner syndrome; OMIM #218330) is an autosomal recessive disorder reported only in 15 cases, which is characterized by dolichocephaly, rhizomelic dwarfism, dental and nail dysplasia, and progressive tubulo-interstitial nephritis (TIN) leading to end-stage renal failure. Herein, we describe a new patient with cranio-ectodermal dysplasia. Unlike previously reported cases, this 4-year-old child presented with tubulo-interstitial nephropathy associated with liver cystic disease and elevated liver enzymes. The liver biopsy demonstrated congenital hepatic fibrosis secondary to ductal plate malformation. The coexistence of a chronic tubulo-interstitial renal disease with lesions associated to malformations of the hepatic ductal plate indicates that CED as a new member of the congenital hepatorenal fibrocystic syndromes.     

Mutational analysis of the ATRX gene by DGGE: a powerful diagnostic approach for the ATRX syndrome

Molecular defects affecting the ATRX gene lead to the ATRX syndrome (alpha thalassemia/mental retardation syndrome, X-linked), characterized by severe mental retardation, microcephaly, distinct facial dysmorphism, and genital abnormalities, as well as a wide spectrum of other pathological features. Alpha thalassemia is frequent but does not represent a constant characteristic of the syndrome. An expanding phenotype of the ATRX gene (a RAD54 homologue encoding a putative zinc-finger helicase) has been demonstrated as a result of the association of single mutations with specific X-linked mental retardation syndromes. To date, mutational analysis of the gene has been based on direct DNA sequencing or using methods with a lower detection rate. In this paper, we present a broad-range DGGE method for single-step mutation scanning of the entire open reading frame (ORF) and canonical splice sites of the gene. Using this method, we successfully identified five novel sequence changes in the ATRX gene, including four missense mutations (K1733E, R2085C, D2136N, T2169A) and one polymorphism (IVS5+35G>A).     

Two novel heterozygous mutations of EVC2 cause a mild phenotype of Ellis-van Creveld syndrome in a Chinese family

Ellis–van Creveld syndrome (EvC, chondroectodermal dysplasia; OMIM 225500) is an autosomal recessive skeletal dysplasia with associated multisystem involvement. The syndrome is characterized by short limbs, short ribs, postaxial polydactyly, dysplastic nails, and abnormal teeth. Congenital heart defects occur in 50–60% of cases. In this study, we report EvC in a 6‐year‐old Chinese girl with hypodontia and polydactyly, mild short stature, and abnormalities of the knee joints. No signs of short ribs, narrow thorax, or congenital heart defects were found in this patient. The EvC phenotype shares some similarity with Weyers acrofacial dysostosis (Weyer; OMIM 193530), an autosomal dominant disorder clinically characterized by mild short stature, postaxial polydactyly, nail dystrophy, and dysplastic teeth. Mutations in EVC or EVC2 are associated with both EvC syndrome and Weyers acrodental dysostosis, but the two conditions differ in the severity of the phenotype and their pattern of inheritance. In this study, two novel heterozygous EVC2 mutations, IVS5‐2A > G and c.2653C > T (Arg885X), were identified in the patient. The IVS5‐2A > G mutation was inherited from the patient's mother and the c.2653C > T from her father. Her parents have no phenotypic symptoms similar to those of the patient. These findings extend the mutation spectrum of this malformation syndrome and provide the possibility of prenatal diagnosis for future offspring in this family. © 2011 Wiley‐Liss, Inc.     

Jervell and Lange-Nielsen syndrome: novel compound heterozygous mutations in the KCNQ1 in a Korean family

The Jervell and Lange-Nielsen syndrome (JLNS) is an autosomal recessive syndrome characterized by congenital deafness and cardiac phenotype (QT prolongation, ventricular arrhythmias, and sudden death). JLNS has been shown to occur due to homozygous mutation in KCNQ1 or KCNE1. There have been a few clinical case reports on JLNS in Korea; however, these were not confirmed by a genetic study. We identified compound heterozygous mutations in KCNQ1 in a 5-yr-old child with JLNS, who visited the hospital due to recurrent syncope and seizures and had congenital sensorineural deafness. His electrocardiogram revealed a markedly prolonged corrected QT interval with T wave alternans. The sequence analysis of the proband revealed the presence of novel compound heterozygous deletion/splicing error mutations (c.828-830 delCTC, p.S277del/c.921G>A, p.V307V). Each mutation in KCNQ1 was identified on the maternal and paternal side. With β-blocker therapy the patient has remained symptom-free for three and a half years.     

sel-10, a negative regulator of lin-12 activity in Caenorhabditis elegans, encodes a member of the CDC4 family of proteins

Mutations that influence lin-12 activity in Caenorhabditis elegans may identify conserved factors that regulate the activity of lin-12/Notch proteins. We describe genetic evidence indicating that sel-10 is a negative regulator of lin-12/Notch-mediated signaling in C. elegans. Sequence analysis shows that SEL-10 is a member of the CDC4 family of proteins and has a potential human ortholog. Coimmunoprecipitation data indicate that C. elegans SEL-10 complexes with LIN-12 and with murine Notch4. We propose that SEL-10 promotes the ubiquitin-mediated turnover of LIN-12/Notch proteins, and discuss potential roles for the regulation of lin-12/Notch activity by sel-10 in cell fate decisions and tumorigenesis.     

DRhoGEF2 encodes a member of the Dbl family of oncogenes and controls cell shape changes during gastrulation in Drosophila

We have identified a gene, DRhoGEF2, which encodes a putative guanine nucleotide exchange factor belonging to the Dbl family of oncogenes. DRhoGEF2 function is essential for the coordination of cell shape changes during gastrulation. In the absence of maternal DRhoGEF2 gene activity, mesodermal and endodermal primordia fail to invaginate. The phenotype seen in DRhoGEF2 mutants is more severe than the defects associated with mutations in two previously identified gastrulation genes, folded gastrulation and concertina, suggesting that DRhoGEF2 acts in a signaling pathway independent of these genes. Expression of dominant-negative DRhoA during gastrulation results in phenocopies of the DRhoGEF2 mutant, suggesting that a signaling cascade involving DRhoGEF2 and the small GTPase DRhoA is responsible for the regulation of cell shape changes during early Drosophila morphogenesis.     

Molecular cloning of a member of the gene family that encodes pMGA, a hemagglutinin of Mycoplasma gallisepticum.

A hemagglutinin with an M(r) of 67,000 (pMGA) from Mycoplasma gallisepticum S6 was purified by using monoclonal antibody affinity chromatography. Purified pMGA was treated with a number of enzymes, the resultant peptides were purified, and their amino acid sequence was determined by using an Applied Biosystems (model 471A) protein sequencer. The DNA sequence encoding two peptides was used to dictate the sequences of synthetic oligonucleotides which were used to screen a library of EcoRI-cut M. gallisepticum DNA in pUC18. A clone reactive to both probes was isolated and found to contain a recombinant insert of 10 kb. The clone was mapped by using restriction endonucleases and fragments subcloned into pUC18 for DNA sequencing. Analysis of part of the DNA sequence revealed an open reading frame containing 1,941 nucleotides which encoded 647 amino acids. The amino terminus was preceded by a putative leader sequence of 25 amino acids. A promoter region preceding the putative start codon GUG was also located. This gene would encode a mature protein of 67,660 Da. There were a number of differences between the predicted amino acid sequence and that determined by direct peptide sequencing. Also, two tryptic peptides of pMGA were not found in the DNA sequence. This suggested that the cloned gene did not encode pMGA but did encode a homolog (pMGA1.2). Furthermore, downstream of pMGA1.2 was a region of DNA encoding a leader sequence followed by an amino acid sequence with high homology to that encoded by the pMGA1.2 gene. The presence within M. gallisepticum of a family of pMGA genes is inferred from the DNA sequence and Southern transfer data. A possible role for this gene family in immune evasion is discussed.     

Epigenetic abnormality: a possible mechanism underlying the fetal origin of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common, yet heterogeneous and complex, endocrine disorders in women of reproductive age. Although the aetiology of PCOS remains uncertain, emerging evidence has indicated that exposure of the female fetus to the hyperandrogenism milieu in utero may result in PCOS phenotype after birth. Such a phenomenon has been formulated as the fetal origin of PCOS, which intends to give a possible explanation for PCOS aetiology. Given that the epigenetic modifications are usually involved in the development and inheritance of many adult diseases with fetal origin, we propose a hypothesis here referred to as "epigenetic abnormality underlying the fetal origin of PCOS". It states that in utero hyperandrogenism exposure may disturb the epigenetic reprogramming in fetal reproductive tissue, thereby resulting in postnatal POCS phenotype in women of reproductive age. Meanwhile, the incomplete erasure of such epigenetic abnormality in germ cells after fertilization may promote the transgenerational inherence of POCS. Thus, this epigenetic abnormality hypothesis has established a novel mechanism for PCOS development and inheritance. If verified, our hypothesis would open new avenues for the possible intervention at the critical period of prenatal life to prevent PCOS development and inheritance in adult women. Moreover, analysis of the epigenetic phenotypes and identification of specific epigenetic changes may help develop new tools for monitoring fetal development under an in utero hyperandrogenism environment.