Munis Dundar

Loss of Dermatan-4-Sulfotransferase 1 Function Results in Adducted Thumb-Clubfoot Syndrome

Adducted thumb-clubfoot syndrome is an autosomal-recessive disorder characterized by typical facial appearance, wasted build, thin and translucent skin, congenital contractures of thumbs and feet, joint instability, facial clefting, and coagulopathy, as well as heart, kidney, or intestinal defects. We elucidated the molecular basis of the disease by using a SNP array-based genome-wide linkage approach that identified distinct homozygous nonsense and missense mutations in CHST14 in each of four consanguineous families with this disease. The CHST14 gene encodes N-acetylgalactosamine 4-O-sulfotransferase 1 (D4ST1), which catalyzes 4-O sulfation of N-acetylgalactosamine in the repeating iduronic acid-alpha1,3-N-acetylgalactosamine disaccharide sequence to form dermatan sulfate. Mass spectrometry of glycosaminoglycans from a patients fibroblasts revealed absence of dermatan sulfate and excess of chondroitin sulfate, showing that 4-O sulfation by CHST14 is essential for dermatan sulfate formation in vivo. Our results indicate that adducted thumb-clubfoot syndrome is a disorder resulting from a defect specific to dermatan sulfate biosynthesis and emphasize roles for dermatan sulfate in human development and extracellular-matrix maintenance.

Genotype–phenotype correlation in children with familial Mediterranean fever in a Turkish population

Background: The aim of the present study was not only to review clinical and demographic features of child‐onset familial Mediterranean fever (FMF) patients but also to investigate whether there is a phenotype–genotype correlation in the same patient population.

Loss of dermatan sulfate epimerase (DSE) function results in musculocontractural Ehlers–Danlos syndrome

The sulfated polysaccharide dermatan sulfate (DS) forms proteoglycans with a number of distinct core proteins. Iduronic acid-containing domains in DS have a key role in mediating the functions of DS proteoglycans. Two tissue-specific DS epimerases, encoded by DSE and DSEL, and a GalNAc-4-O-sulfotransferase encoded by CHST14 are necessary for the formation of these domains. CHST14 mutations were previously identified for patients with the musculocontractural type of Ehlers-Danlos syndrome (MCEDS). We now identified a homozygous DSE missense mutation (c.803C>T, p.S268L) by the positional candidate approach in a male child with MCEDS, who was born to consanguineous parents. Heterologous expression of mutant full-length and soluble recombinant DSE proteins showed a loss of activity towards partially desulfated DS. Patient-derived fibroblasts also showed a significant reduction in epimerase activity. The amount of DS disaccharides was markedly decreased in the conditioned medium and the cell fraction from cultured fibroblasts of the patient when compared with a healthy control subject, whereas no apparent difference was observed in the chondroitin sulfate (CS) chains from the conditioned media. However, the total amount of CS disaccharides in the cell fraction from the patient was increased ∼1.5-fold, indicating an increased synthesis or a reduced conversion of CS chains in the cell fraction. Stable transfection of patient fibroblasts with a DSE expression vector increased the amount of secreted DS disaccharides. DSE deficiency represents a specific defect of DS biosynthesis. We demonstrate locus heterogeneity in MCEDS and provide evidence for the importance of DS in human development and extracellular matrix maintenance.

Common Familial Mediterranean Fever gene mutations in a Turkish cohort

Familial Mediterranean Fever (FMF) is an autosomal recessive autoinflammatory disorder with the responsible gene of MEFV which primarily affects Jewish, Armenian, Turkish and Arab populations. The FMF gene (MEFV) has recently been cloned to chromosome 16p, which encodes pyrin. In the present study, we enrolled 2,067 unrelated patients with the suspicion of FMF in Middle Anatolia between the years 2006–2009 and identified the 12 MEFV mutations. DNA was amplified by PCR and subjected to reverse hybridization for the detection of MEFV gene mutations. Among the 2,067 patients, 866 (41.9%) were males and 1,201 (58.1%) were females. The mutations were homozygous in 176 (16.85%) patients, compound heterozygous in 314 (30.1%) patients, heterozygous in 546 (52.25%) patients and the other forms of mutations were found in 8 patients (0.76%). No mutation was detected in 1,023 (49.5%) patients. The most frequent mutations were M694V, M680I (G/C), E148Q and V726A. We could not find any significant differences between the two common mutations according to the gender. The high incidence of MEFV gene mutations in the Turkish population indicated that newborn screening may be discussed in the future. Because of the ethnic origin of Anatolia, larger serial analyses are necessary to investigate the rate and coexistence of these mutations.

Apolipoprotein E3/E3 genotype decreases the risk of pituitary dysfunction after traumatic brain injury due to various causes: preliminary data.

Traumatic brain injury (TBI) is a devastating public health problem which may result in hypopituitarism. However, the mechanisms and the risk factors responsible for hypothalamo-pituitary dysfunction due to TBI are still unclear. Although APO E is one of the most abundant protein in hypothalamo-pituitary region, there is no study investigating the relation between APO E polymorphism and TBI-induced hypopituitarism. This study was undertaken to determine whether APO E genotypes modulate the pituitary dysfunction risk after TBI due to various causes, including traffic accident, boxing, and kickboxing. Ninety-three patients with TBI (mean age, 30.61 +/- 1.25 years) and 27 healthy controls (mean age, 29.03 +/- 1.70 years) were included in the study. Pituitary functions were evaluated, and APO E genotypes (E2/E2; E3/E3; E4/E4; E2/E3; E2/E4; E3/E4) were screened. Twenty-four of 93 subjects (25.8%) had pituitary dysfunction after TBI. The ratio of pituitary dysfunction was significantly lower in subjects with APO E3/E3 (17.7%) than the subjects without APO E3/E3 genotype (41.9%; p = 0.01), and the corresponding odds ratio was 0.29 (95% confidence interval [CI], 0.11-0.78). In conclusion, this study provides strong evidence for the first time that APO E polymorphism is associated with the development of TBI-induced pituitary dysfunction. Present data demonstrated that APO E3/E3 genotype decreases the risk of hypopituitarism after TBI. The demonstration of the association between the APO E polymorphism and TBI may provide a new point of view in this field and promote further studies.

An autosomal recessive adducted thumb‐club foot syndrome observed in Turkish cousins

Male and female cousins, the offspring of consanguineous Turkish parents, have been affected by a hitherto unreported combination of problems comprising moderate to severe psychomotor developmental delay, ocular anterior chamber abnormality, facial dysmorphisms (broad, bossed forehead, late‐closing fontanelle, telecanthus, downslanting palpebral fissures, posteriorly rotated ears, downturned angles of mouth), arachnodactyly and distal arthrogryposis with severely adducted thumbs and club feet. This striking phenotype has some similarities with the multiple pterygium syndrome (Escobar syndrome), but it most likely represents a distinct condition caused by an autosomal recessive gene defect.

Circulating microRNAs in patients with non-alcoholic fatty liver disease

AIM To identify novel non-invasive biomarkers for non-alcoholic fatty liver disease (NAFLD). METHODS Twenty patients with histologically proven NAFLD and 20 controls were included. All NAFLD cases were scored using the NAFLD activity score. The relative expressions of miR-197, miR-146b, miR-10b, miR-181d, miR-34a, miR-122, miR-99a and miR-29a were analyzed using real-time polymerase chain reaction. RESULTS Serum levels of miR-181d, miR-99a, miR-197 and miR-146b were significantly lower in biopsy-proven NAFLD patients than in the healthy controls. Serum levels of miR-197 and miR-10b were inversely correlated with degree of inflammation and miR-181d and miR-99a were inversely correlated with serum gamma glutamyl transferase levels in non-alcoholic steatohepatitis patients. CONCLUSION NAFLD is associated with altered serum miRNA expression pattern. This study provides clues for defining the non-invasive diagnosis of NAFLD.

Inherited diseases and syndromes leading to aortic aneurysms and dissections

Genes affect virtually all human characteristics and diseases. These influences can be ascertained in individual patients through a review of the family history, physical examination and the use of medical diagnostics. Aneurysms and dissections are a leading cause of morbidity and mortality, in addition to medical expense, and, on the whole, their specific molecular mechanisms are beginning to be identified. Over the past decade, genetic tests have become available for numerous heritable disorders especially inherited with mendelian models. An important fact is that the results of genetic tests may also be useful beyond the individual affected by the genetic disorder. Depending upon the disorder, knowledge of carrier status may be important. Because of these facts, some essential information regarding basic genetics of aneurysm and dissection has been presented in this study.

Loss of dermatan-4-sulfotransferase 1 (D4ST1/CHST14) function represents the first dermatan sulfate biosynthesis defect, "dermatan sulfate-deficient adducted thumb-clubfoot syndrome".

A recent article in Human Mutation [Miyake et al., 2010] citing loss-of-function mutations in CHST14 (MIM] 608429) as a ‘‘new’’ disease entity in the Ehlers-Danlos syndrome (EDS) category will potentially lead to confusion on the part of both clinicians and researchers. Malfait et al. [2010] have noted in a current Human Mutation article that a set of patients categorized as EDS have the same defect as those we described as having ‘‘Adducted thumb–clubfoot syndrome’’ (ATCS). In a series of three articles, we delineated the phenotypic spectrum of a generalized connective tissue disorder we termed ATCS and established OMIM entry ]601776 in 1997 [Dundar et al., 1997, 2001, 2009; Janecke et al., 2001]. In 2009, we identified the molecular basis for ATCS as a consequence of CHST14 loss-offunction mutations and described the resulting biochemical abnormalities [Dundar et al., 2009]. In our opinion, the six and three patients described in the two studies published in Human Mutation [Malfait et al., 2010; Miyake et al., 2010] represent further instances of ATCS. In their Human Mutation article, Miyake et al. [2010] indicate ‘‘they analyzed six Japanese patients clinically diagnosed as showing a specific type of EDS resembling the kyphoscoliosis type EDS’’ (MIM] 225400). More detailed phenotypic data is available in an accompanying article published in the American Journal of Medical Genetics [Kosho et al., 2010]. The clinical descriptions and the photographs of their patients collectively describe features that are characteristic for ATCS; namely, characteristic facial appearance with broad and flat forehead, hypertelorism, downward slanting palpebral fissures, malar flatness, retrognathia, brachycephaly, and prominent ears; the anterior fontanel is large at birth and closure is delayed. There are congenital contractures of the thumbs or other digits. The patients present with a typical, severely wasted build, also referred to as ‘‘Marfanoid habitus,’’ and marked arachnodactyly and tapering of the fingers, fine palmar creases, as well as hypermobility of the small joints of the hands and shoulders are noted. The prominent feature of congenital foot malformations is present in all the patients they describe, delineated as clubfeet in ATCS and in its milder form as talipes equinovares. Furthermore, at least one of the symptoms of disturbed blood coagulation, delayed wound healing, ecchymoses, and hematoma formation that we described in ATCS was present in each of their patients [Dundar et al., 1997, 2001, 2009; Janecke et al., 2001; Kosho et al., 2010]. Although there are minor differences in the clinical findings reported in each article dealing with CHST14 mutations, all are well within the range of expected clinical variability. We previously noted that ATCS represents a recognizable, generalized connective tissue disorder with normal cognitive development, keeping in mind that congenital foot malformations sometimes cause motor delay [Dundar et al., 2009]. ATCS resembles, but is distinct from other entities with a known molecular basis; that is, both the progeroid and vascular types of Ehlers-Danlos syndrome (EDS; MIM]s 130070, 130050), the Loeys-Dietz syndrome (LDS; MIM] 609192), collagen VI-related muscle disorders (Bethlem myopathy; MIM] 158810), and autosomal recessive cutis laxa type II, a type II N-glycosylation defect (ARCL2; MIM] 219200). We found that a wide spectrum of congenital malformations occur variably in ATCS. We have shown that the patients we clinically delineated as ATCS, from four families of Austrian, Turkish, and Japanese origin, all harbored CHST14 loss-of-function mutations on both alleles [Dundar et al., 2009]. CHST14 encodes dermatan-4-Osulfotransferase-1 (D4ST1), a sulfotransferase that we determined catalyzes 4-O sulfation of N-acetylgalactosamine in the repeating iduronic acid-alpha1,3-N-acetylgalactosamine disaccharide sequence to form dermatan sulfate [Evers et al., 2001]. Fibroblasts from one of our patients did not synthesize dermatan sulfate but instead produced an excess of chondroitin sulfate [Dundar et al., 2009]. Based on the description of 9 additional patients that have the same features as the 11 patients we originally described as having ATCS we believe the data presented in both new Human Mutation papers [Malfait et al., 2010; Miyake et al., 2010] supports our report [Dundar et al., 2009] that CHST14 loss-of-function mutations cause ATCS. Further support for our conclusion that this is a single disease entity, ATCS, comes from the fact that we described the CHST14 mutation p.Y293C in two Japanese patients and this mutation is present in two of the six patients reported by Miyake et al. [2010]. The use of different designations [Miyake et al., 2010] for the identical clinical and molecular entity will lead to confusion, especially for those who are not working in the field of connective tissue disorders. We are therefore left with the challenge of determining what name would be most appropriate. Features such as joint laxity, skin hyperextensibility/fragility, and bleeding diathesis, which are described in these patients, are also typical of EDS. In contrast, the presence of multiple congenital malformations such as facial dysmorphism, cleft lip/palate, intestinal abnormalities, renal abnormalities, and features such as nephrolithiasis and muscle hypotonia in these patients are not typical in EDS. Only a small subset of patients with clinical syndromes that include joint laxity with or without skin manifestations are considered a form of EDS. The molecular basis for the features seen in the patients described in the cited reports [Dundar et al., 1997, 2001, 2009; Janecke et al., 2001; Kosho et al., 2010; Malfait et al., 2010] and EDS differs substantially. Furthermore, the clinical spectrum of CHST14 mutations extends well beyond the features of most types of EDS, so that including ‘‘EDS’’ in the name for this syndrome generates confusion in the area of connective tissue disorders both for clinicians and their patients. We therefore propose the term ‘‘Dermatan sulfate-deficient adducted thumb– clubfoot syndrome,’’ representing another congenital disorder of glycosylation [Zhang et al., 2010]. We feel this designation is particularly appropriate because it provides both an indication of the molecular basis for the phenotype and the clinical manifestations. OFFICIAL JOURNAL

A novel acropectoral syndrome maps to chromosome 7q36

F syndrome (acropectorovertebral syndrome) is a dominantly inherited skeletal dysplasia affecting the hands, feet, sternum, and lumbosacral spine, which has previously been described in only two families. Here we report a six generation Turkish family with a related but distinct dominantly inherited acropectoral syndrome. All 22 affected subjects have soft tissue syndactyly of all fingers and all toes and 14 also have preaxial polydactyly of the hands and/or feet. In addition, 14 have a prominent upper sternum and/or a blind ending, inverted U shaped sinus in the anterior chest wall. Linkage studies and haplotype analysis carried out in 16 affected and nine unaffected members of this family showed that the underlying locus maps to a 6.4 cM interval on chromosome 7q36, between EN2and D7S2423, a region to which a locus for preaxial polydactyly and triphalangeal thumb-polysyndactyly has previously been mapped. Our findings expand the range of phenotypes associated with this locus to include total soft tissue syndactyly and sternal deformity, and suggest that F syndrome may be another manifestation of the same genetic entity. In mice, ectopic expression of the geneSonic hedgehog(Shh) in limb buds and lateral plate mesoderm during development causes preaxial polydactyly and sternal defects respectively, suggesting that misregulation ofSHH may underlie the unusual combination of abnormalities in this family. A recently proposed candidate gene for 7q36 linked preaxial polydactyly is LMBR1, encoding a novel transmembrane receptor which may be an upstream regulator of SHH.