Immunomodulatory Functions of Adipose Mesenchymal Stromal/Stem Cell Derived From Donors With Type 2 Diabetes and Obesity on CD4 T Cells.

For adipose stromal/stem cell (ASCs)-based immunomodulatory therapies, it is important to study how donor characteristics, such as obesity and type 2 diabetes (T2D), influence ASCs efficacy. Here, ASCs were obtained from 2 groups, donors with T2D and obesity (dASCs) or nondiabetic donors with normal-weight (ndASCs), and then cultured with anti-CD3/CD28-stimulated allogeneic CD4 T cells. ASCs were studied for the expression of the immunomodulators CD54, CD274, and indoleamine 2, 3 dioxygenase 1 (IDO) in inflammatory conditions. CD4 T cells cultured alone or in cocultures were assessed to evaluate proliferation, activation marker surface expression, apoptosis, the regulatory T cells (Tregs; CD4+ CD25high FOXP3+) frequency, and intracellular cytokine expression using flow cytometry. Modulation of T-cell subset cytokines was explored via ELISA. In inflammatory conditions, the expression of CD54, CD274, and IDO was significantly upregulated in ASCs, with no significant differences between ndASCs and dASCs. dASCs retained the potential to significantly suppress CD4 T-cell proliferation, with a slightly weaker inhibitory effect than ndASCs, which was associated with significantly reduced abilities to decrease IL-2 production and increase IL-8 levels in cocultures. Such attenuated potentials were significantly correlated with increasing body mass index. dASCs and ndASCs comparably reduced CD4 T-cell viability, HLA-DR expression, and interferon-gamma production and conversely increased CD69 expression, the Tregs percentage, and IL-17A production. Considerable amounts of the immunomodulators prostaglandin E2 (PGE2) and IL-6 were detected in the conditioned medium of cocultures. These findings suggest that ASCs obtained from donors with T2D and obesity are receptive to the inflammatory environment and able to modulate CD4 T cells accordingly.

Serum MicroRNA profiles in chronic hepatitis C Egyptian patients before and after combined sofosbuvir and daclatasvir treatment.

BACKGROUND: MicroRNAs (miR) are small sequence of nucleotides that can affect multiple genes involved in the hepatitis C virus (HCV) life cycle and disease development. The purpose of the present study was to investigate the clinical significance of serum microRNA profiles in a cohort of Egyptian patients with chronic HCV infection before and after combined sofosbuvir and daclatasvir treatment, as well as to gain a better understanding of the exact interaction mechanism in HCV transcriptional activity via differentially expressed miRNAs. For 12 weeks, 50 patients were eligible for and received sofosbuvir (400 mg daily) and daclatasvir (60 mg daily) treatment. Each patient's blood was obtained twice: once before therapy began and again three months afterwards. RESULTS: The current study found that serum levels of circulating miR-122, miR-221, miR-23a, miR-125, miR-217, miR-224, and miR-181a were high in HCV pre-treatment patients, but after 12 weeks of direct-acting antiviral (DAAs) treatment, there was a statistically significant reduction in expression levels of miR-122, miR-221, miR-23a, miR-125, miR-217, and miR-224 (p < 0.001). There is no statistical significance for miR-181a. CONCLUSION: The key differentially expressed microRNAs before and after the direct-acting antiviral (DAA) regimen were connected to the dynamics of chronic HCV infection, suggesting their potential as predictive biomarkers for HCV clearance after sofosbuvir and daclatasvir therapy.

Clinical and molecular characterization in a cohort of patients with progressive pseudorheumatoid dysplasia.

Progressive pseudorheumatoid dysplasia (PPRD), a rare autosomal recessive syndrome, is a type of skeletal dysplasia associated with pain, stiffness, swelling of multiple joints, and the absence of destructive changes. PPRD occurs due to loss of function pathogenic variants in WISP3 (CCN6) gene, located on chromosome 6q22. In this study, 23 unrelated Egyptian PPRD patients were clinically diagnosed based on medical history, physical and radiological examinations, and laboratory investigations. Sequencing of the whole WISP3 (CCN6) exons and introns boundaries was carried out for all patients. A total of 11 different sequence variations were identified in the WISP3 (CCN6) gene, five of them were new pathogenic variants: the NM_003880.3: c.80T>A (p.L27*), c.161delG (p.C54fs*12), c.737T>C (p.Leu246Pro), c.347-1G>A (IVS3-1G>A), and c.376C>T (p.Q126*). The results of this study expand the spectrum of WISP3 (CCN6) pathogenic variants associated with PPRD. Clinical and genetic analysis is important for proper genetic counseling to curb this rare disorder in the families.

Study the association of microRNA polymorphisms (miR-146a, miR-4513) with the risk of coronary heart diseases in Egyptian population.

Coronary heart disease (CHD) is the most prevalent cause of cardiovascular mortality in the world. It is well established that microRNAs (miRNAs) and their variants have an essential role in regulating the development of cardiovascular physiology, thus impacting the pathophysiology of heart diseases. This study was designed to determine the possible association of miRNA polymorphisms (miRNA-146a rs2910164C/G and miR-4513 rs2168518G/A) with susceptibility to CHD in Egyptian patients and their correlation with different biochemical parameters. The study comprised 300 participants, including 200 unrelated patients with CHD and 100 healthy controls. Anthropometric and blood biochemical parameters were measured as well genetic analysis for rs2910164C/G and rs2168518G/A polymorphisms were performed for all subjects using TaqMan real-time PCR assay. Our results revealed that the biomedical parameters have a significant correlation between CHD patients and healthy controls with a p < 0.05. Analyses of genotype distribution for (rs2910164 and rs2168518) revealed a significant association with CHD [odd ratio = 4.54, confidence interval (CI 95%) = (2.41-8.53)] and [odd ratio = 0.88, (CI 95%) = (0.83-0.92)], respectively. Furthermore, a statistically significant difference was detected between lipid profile levels and both rs2910164 and rs2168518 polymorphisms. The present study's findings indicated that the selected polymorphisms, miR-146a rs2910164 and miR-4513 rs2168518 could represent a useful biomarker for susceptibility to CHD in the Egyptian population. These genetic characteristics and personal habits and environmental factors may contribute to the development of CHD.

A novel variant in GNPNAT1 gene causing a spondylo-epi-metaphyseal dysplasia resembling PGM3-Desbuquois like dysplasia.

Spondylo-epi-metaphyseal dysplasias (SEMDs) are a clinically and genetically heterogeneous group of skeletal dysplasias characterized by short stature and abnormal modeling of the spine and long bones. A novel form of rhizomelic skeletal dysplasia, Ain-Naz type, associated with a homozygous variant in GNPNAT1 was recently identified. Herein, we report an Egyptian patient, offspring of consanguineous parents, who presented with a severe form of unclassified SEMD. Whole exome sequencing identified a novel homozygous variant in exon 3, c.77T>G, (p.Phe26Cys) in GNPNAT1, that was confirmed by Sanger sequencing and both parents were found to be heterozygous for the identified variant. Main features included severe short stature, rhizomelic limb shortening, and wide flared metaphysis. Short broad long bones, brachydactyly, delayed epiphyseal ossification of long bones, advanced bone age, and immunodeficiency were additional findings expanding the clinical phenotype described in the previously reported family. We conclude that variants in the GNPNAT1 gene cause an autosomal recessive form of SEMD resembling Desbuquois like dysplasia caused by PGM3, which is involved in the same pathway as GNPNAT1.

Advances in genomic diagnosis of a large cohort of Egyptian patients with disorders of sex development.

Disorders/differences of sex development (DSD) comprise a group of congenital disorders that affect the genitourinary tract and usually involve the endocrine and reproductive system. The aim of this work was to identify genetic variants responsible for disorders of human urogenital development in a cohort of Egyptian patients. This three-year study included 225 patients with various DSD forms, referred to the genetic DSD and endocrinology clinic, National Research Centre, Egypt. The patients underwent thorough clinical examination, hormonal and imaging studies, detailed cytogenetic and fluorescence in situ hybridization analysis, and molecular sequencing of genes known to commonly cause DSD including AR, SRD5A2, 17BHSD3, NR5A1, SRY, and WT1. Whole exome sequencing (WES) was carried out for 18 selected patients. The study revealed a high rate of sex chromosomal DSD (33%) with a wide array of cytogenetic abnormalities. Sanger sequencing identified pathogenic variants in 33.7% of 46,XY patients, while the detection rate of WES reached 66.7%. Our patients showed a different mutational profile compared with that reported in other populations with a predominance of heritable DSD causes. WES identified rare and novel pathogenic variants in NR5A1, WT1, HHAT, CYP19A1, AMH, AMHR2, and FANCA and in the X-linked genes ARX and KDM6A. In addition, digenic inheritance was observed in two of our patients and was suggested to be a cause of the phenotypic variability observed in DSD.

Study of DYRK1B gene expression and its association with metabolic syndrome in a small cohort of Egyptians.

BACKGROUND: A cluster of many risk factors for type 2 diabetes and cardiovascular disease is used to describe the metabolic syndrome (MetS). Moreover, genetic differences associated with metabolic syndrome play a key role in its prevalence and side effects. This study aims to investigate the expression of DYRK1B and its association with metabolic syndrome in a small cohort of Egyptian. MATERIALS AND METHODS: A total of 100 adult Egyptians (50 with MetS and 50 healthy control subjects) were included to this study. Clinical, biochemical and anthropometric analysis were assessed. Relative gene expressions of DYRK1B were compared between two groups of subjects using real time PCR. RESULTS: We observed marked overexpression in DYRK1B (p < 0.05) in MetS subjects when compared with the healthy control subjects. CONCLUSION: This is the first study to provide evidence that DYRK1B is highly expressed among the MetS subjects.

Early-infantile onset epilepsy and developmental delay caused by bi-allelic GAD1 variants.

Gamma-aminobutyric acid (GABA) and glutamate are the most abundant amino acid neurotransmitters in the brain. GABA, an inhibitory neurotransmitter, is synthesized by glutamic acid decarboxylase (GAD). Its predominant isoform GAD67, contributes up to ∼90% of base-level GABA in the CNS, and is encoded by the GAD1 gene. Disruption of GAD1 results in an imbalance of inhibitory and excitatory neurotransmitters, and as Gad1-/- mice die neonatally of severe cleft palate, it has not been possible to determine any potential neurological dysfunction. Furthermore, little is known about the consequence of GAD1 disruption in humans. Here we present six affected individuals from six unrelated families, carrying bi-allelic GAD1 variants, presenting with developmental and epileptic encephalopathy, characterized by early-infantile onset epilepsy and hypotonia with additional variable non-CNS manifestations such as skeletal abnormalities, dysmorphic features and cleft palate. Our findings highlight an important role for GAD1 in seizure induction, neuronal and extraneuronal development, and introduce GAD1 as a new gene associated with developmental and epileptic encephalopathy.

Cyclooxygenase-2 Gene Polymorphisms -765G>C and -1195A>G and Mycosis Fungoides Risk.

BACKGROUND: Cyclooxygenase-2 (COX-2) is an inducible modulator of inflammation that acts through increasing prostaglandin levels and has been described as a major mediator linking inflammation to cancer. Previous studies supported that COX-2-765G>C and -1195A>G polymorphisms were associated with increased risk of several solid tissue cancers as well as some hematological malignancies. OBJECTIVE: The aim of the study was to elucidate the association between functional COX-2 genotypes (-765G>C and -1195A>G) polymorphisms and the risk of developing mycosis fungoides (MF). METHODS: This was a hospital-based, case-control study of 70 MF patients and 100 MF-free controls. We genotyped COX-2 -1195A>G, -765G>C, and -8473T>C polymorphisms by using the PCR-restriction fragment length polymorphism method. RESULTS: The AA genotype in the COX-2 -1195A>G gene polymorphism and the GC genotype in the COX-2 -765G>C gene were significantly more frequent among MF patients compared to controls (p< 0.001 and p = 0.002, respectively). CONCLUSION: The -results indicate a possible role of COX-2 genes in the pathogenesis of MF. These novel findings may allow for notable future advances, as it will enable the identification of the -individuals most susceptible to MF.

JAK1 rs310241 and JAK3 rs3008 Genotypes May Increase Susceptibility to Psoriasis: A Case Control Study.

BACKGROUND: Janus kinases (JAKs) are a family of non-receptor protein tyrosine kinases that are expressed in a variety of tissues. Several JAK-controlled cytokine receptor pathways are incriminated in the initiation and progression of psoriasis. Genetic polymorphisms influencing JAK expression would be anticipated to have a great impact on disease activity. OBJECTIVE: The aim of the study was to evaluate the association between JAK1 rs310241 and JAK3 rs3008 polymorphisms and the risk of developing psoriasis. METHODS: Blood samples of 150 patients and 120 controls were screened for nucleotide polymorphisms in JAK1 rs310241 and JAK3 rs3008 genes by using polymerase chain reaction (PCR)-restriction fragment length polymorphism technique. RESULTS: The GG genotype of the JAK1 rs310241 and JAK3 rs3008 genes was significantly associated with an increase in psoriasis risk (p = 0.000, OR = 7.7, 95% CI = 2.8-21.5; p = 0.003, OR = 3.3, 95% CI = 1.5-6.9, respectively). The G allele of both genes was also associated with psoriasis susceptibility (p = 0.000, OR = 2.0, 95% CI = 1.4-2.8; p = 0.002, OR = 1.7, 95% CI = 1.2-2.4, respectively). CONCLUSION: The results indicate a possible association between JAK1 rs310241 and JAK3 rs3008 gene polymorphisms and susceptibility to psoriasis. These findings validate the importance of these molecules in psoriasis and may enable the identification of the individuals most susceptible to the disease.

Expression of B and T lymphocyte attenuator, retinoid-related orphan receptor gamma-isoform-t and interleukin 7 in psoriasis vulgaris.

BACKGROUND/OBJECTIVES: Psoriasis is one of the immune-mediated inflammatory diseases where CD4+ T lymphocytes, mainly Th1 cells, and B lymphocytes contribute in their pathogenesis through a pro-inflammatory effect, production of antibodies, activation of T cells and cytokine synthesis. B and T lymphocyte attenuator (BTLA) is a co-inhibitory molecule expressed on T and B lymphocytes as well as other immune cells, and it is necessary to inhibit homoeostatic expansion and activation of lymph node and skin-resident γδ T cells. BTLA expression is regulated by RORγt and IL-7. The study aimed at adding more insight on the role played by co-inhibitory molecule BTLA in psoriasis vulgaris and its inter-relation with RORγt and IL-7 to establish a basis for novel treatment strategies. METHODS: This case-control study included 25 patients and 25 controls examined for gene expression of BTLA, RORγt and IL-7. RESULTS: B and T lymphocyte attenuator was significantly lower in psoriasis patients, whereas both RORγt and IL-7 were higher in comparison with controls. A significant positive correlation between disease severity (PASI) and both RORγt and IL-7 as well as between RORγt and IL-7 was found. A significant negative correlation between BTLA and both RORγt and IL-7 was found. Neither the age nor the duration of disease had any correlation with BTLA, RORγt or IL-7. BTLA had no correlation with PASI. Regarding the control group, a significant negative correlation between RORγt and IL-7 was found. CONCLUSION: B and T lymphocyte attenuator, RORγt and IL-7 play an important role in psoriasis.

Expanding the phenome and variome of skeletal dysplasia.

PURPOSE: To describe our experience with a large cohort (411 patients from 288 families) of various forms of skeletal dysplasia who were molecularly characterized. METHODS: Detailed phenotyping and next-generation sequencing (panel and exome). RESULTS: Our analysis revealed 224 pathogenic/likely pathogenic variants (54 (24%) of which are novel) in 123 genes with established or tentative links to skeletal dysplasia. In addition, we propose 5 genes as candidate disease genes with suggestive biological links (WNT3A, SUCO, RIN1, DIP2C, and PAN2). Phenotypically, we note that our cohort spans 36 established phenotypic categories by the International Skeletal Dysplasia Nosology, as well as 18 novel skeletal dysplasia phenotypes that could not be classified under these categories, e.g., the novel C3orf17-related skeletal dysplasia. We also describe novel phenotypic aspects of well-known disease genes, e.g., PGAP3-related Toriello-Carey syndrome-like phenotype. We note a strong founder effect for many genes in our cohort, which allowed us to calculate a minimum disease burden for the autosomal recessive forms of skeletal dysplasia in our population (7.16E-04), which is much higher than the global average. CONCLUSION: By expanding the phenotypic, allelic, and locus heterogeneity of skeletal dysplasia in humans, we hope our study will improve the diagnostic rate of patients with these conditions.

Polymorphisms at IL28B gene as predictors of viral relapse in genotype 4 Egyptian hepatitis C patients.

Chronic HCV is one of the commonest causes of chronic liver disease worldwide with about 15% of population infected in Egypt. Certain single nucleotide polymorphisms (SNPs) lying near the IL28B gene were found to affect the spontaneous clearance as well as treatment outcome of HCV. To examine the association between different IL28B variants and the relapse of HCV infection after combined therapy with ribavirin and pegylated interferon (pegIFN). Hundered HCV genotype four patients received 1.5 mg/kg/week peginterferon alfa-2b plus 800-1400 mg/d ribavirin (weight-adjusted) for 48 weeks. IL28B polymorphisms (rs12980275, rs12979860, and 1 rs8099917) were studied in responders and relapsers at week 72. Out of 69 patients receiving treatment, 13 (18.8%) were relapsers. By stratifying patients on the basis of the IL-28/60 genotype (CC vs. CT/TT), CC patients showed lower relapse rates (2.3%) compared with CT/TT patients (46.2%) (P < 0.001). On the basis of the IL-28/75 genotype (GG vs. GA/AA), the GG patients achieved higher relapse rates (62.5%) compared with GA/AA patients (13.1%) (P = 0.004). Moreover, no statistical significant difference was observed between the TT patients compared with GG/GT patients on the basis of the IL-28/17 genotype. SNPs at IL-28/60 and IL-28/75 are possible predictors of relapse in patients receiving dual treatment.

The role of microRNA-31 and microRNA-21 as regulatory biomarkers in the activation of T lymphocytes of Egyptian lupus patients.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by familial aggregation and genetic predisposition. MicroRNAs (MiRNAs) serve as critical biomarkers in lupus patients because of their aberrant expression in different SLE stages. The study aimed to investigate the correlation of miR-31 and miR-21 with IL-2 in SLE patients as regulatory biomarkers in the activation of T lymphocytes of Egyptian lupus patients. Quantitative RT-PCR is carried out to estimate the expressions of miR-31 and miR-21, and IL-2 levels were determined using ELISA in plasma of 40 patients with SLE, 20 of their first-degree relatives and 20 healthy controls. The study also determined the systemic lupus erythematosus disease activity index (SLEDAI) score and proteinuria in SLE patients. The results revealed that miR-31 was lower expressed, while miR-21 was high expressed in SLE patients compared to their first-degree relatives and controls. MiR-31 was negatively correlated with SLEDAI and proteinuria in lupus patients, while miR-21 showed positive correlation with them. Also we found that there is a significant positive correlation between miR-31 and IL-2 in SLE patients, while miR-21 was negatively correlated with IL-2 level in patients. In conclusion, the study disclosed a significant association between miR-31 and miR-21 expression with IL-2 level in SLE patients. The regulatory biomarkers of miR-31 and miR-21 might have an impact on regulating IL-2 pathway expression and in turn on the activation of T lymphocytes in SLE.

Association of PTPN22 1858C→T polymorphism, HLA-DRB1 shared epitope and autoantibodies with rheumatoid arthritis.

To assess impact of PTPN22 1858C→T polymorphism, HLA shared epitope and autoantibodies on susceptibility and severity of rheumatoid arthritis (RA). A total of 150 RA patients and 150 controls were included in the study. Anti-cyclic citrullinated peptide (anti-CCP) and rheumatoid factor isotypes (IgG, IgM and IgA) were assayed by ELISA. PTPN22 1858C→T polymorphism was performed by RFLP analysis and HLA-DRB1 genotyping by PCR-SSP analysis. Single-view, anteroposterior radiographs of the hands and feet were obtained on all RA patients. The results showed association of PTPN22 1858 T allele with RA (OR = 2.3, 95 % CI 1.5-3.5) and bone erosion (OR = 2.9, 95 % CI 1.1-7.6). The associations increased with the combination of positive autoantibodies, HLA-DRB1 SE with PTPN22 1858 T allele carriage. The highest association was with the combination with anti-CCP antibodies (OR = 47.3, 95 % CI 10.9-204.4 for RA and OR = 69.4, 95 % CI 15.8-305.5 for erosion p < 0.001). Combination of PTPN22 1858 T allele carriage with negative RF isotypes or with absence HLA-DRB1 SE showed no significant association with RA. The presence of PTPN22 1858C→T polymorphism with HLA SE and autoantibodies increases risk of RA development and erosive disease.

Clinical and molecular characterization of seven Egyptian families with autosomal recessive robinow syndrome: Identification of four novel ROR2 gene mutations.

Robinow syndrome (RS) is a rare genetic disorder characterized by limb shortening, genital hypoplasia, and craniofacial/orodental abnormalities. The syndrome follows both autosomal dominant and recessive patterns of inheritance with similar phenotypic presentation and overlapping features. Autosomal recessive Robinow syndrome (ARRS) is caused by mutations in the ROR2 gene. Here, we present the clinical, radiological and molecular findings of 11 Egyptian patients from 7 unrelated consanguineous families with clinical features of ARRS. Mutation analyses of ROR2 gene identified five pathogenic mutations distributed all over the gene. The identified mutations included four novel (G326A, D166H, S677F, and R528Q) and one previously reported (Y192D). Our results extend the number of ROR2 mutations identified so far, suggest a founder effect in the Egyptian population, and emphasize the important role of genetic testing in proper counseling and patients' management.

C242T polymorphism of NADPH oxidase p22phox gene reduces the risk of coronary artery disease in a random sample of Egyptian population.

The p22phox protein subunit is essential for NADPH oxidase activity. The prevalence of C242T variants of p22phox gene was studied in 101 healthy Egyptian controls and 104 acute myocardial infarction (AMI) Egyptian patients. Contribution of oxidative stress, represented by serum oxidized-LDL (ox-LDL), in development of AMI was also examined and correlated with C242T gene variants. Genotyping and ox-LDL were assessed by PCR-RFLP and ELISA. Results showed that wild type CC genotype is prevalent in 27 % of controls; CT and TT are in 72 and 1 %. In patients, the distribution was 40.2, 59.8 and 0 % for CC, CT and TT; respectively, showing a significant difference (p = 0.0259). Serum ox-LDL levels were higher in patients than controls (p ≤ 0.0001). Subjects having CT genotype had lower levels of ox-LDL than CC genotype (p ≤ 0.005). C242T polymorphism of p22phox gene of NADPH oxidase is a novel genetic marker associated with reduced susceptibility to AMI.

Aggrecan-related bone disorders; a novel heterozygous ACAN variant associated with spondyloepimetaphyseal dysplasia expanding the phenotypic spectrum and review of literature.

BACKGROUND: Spondyloepimetaphyseal dysplasias (SEMD) are a large group of skeletal disorders represented by abnormalities of vertebrae in addition to epiphyseal and metaphyseal areas of bones. Several genes have been identified underlying different forms. ACAN gene mutations were found to cause Aggrecan-related bone disorders (spondyloepimetaphyseal dysplasias,spondyloepiphyseal dysplasias, familial osteochondritis dissecans and short stature syndromes). This study aims to find the disease causing variant in Egyptian patient with SEMD using whole exome sequencing. METHODS: Whole-exome sequencing was performed for an Egyptian male patient who presented with short stature, clinical and radiological features suggestive of unclassified SEMD. RESULTS: The study identified a novel de novo heterozygous ACAN gene variant (c.7378G>A; p.Gly2460Arg) in G3 domain. Mutations in ACAN gene have been more commonly associated with short stature than SEMD. The phenotype of our patient was intermediate in severity between spondyloepiphyseal dysplasia presentation; Kimberley type(SEDK) and Spondyloepimetaphyseal dysplasias Aggrecan (SEMDAG) CONCLUSIONS: Whole exome sequencing revealed a novel de novo ACAN gene variant in patient with SEDK. The clinical and skeletal phenotype of our patient was much severe than those reported originally and showed more metaphyseal involvement. To the best of our knowledge, two previous studies reported a heterozygous variant in ACAN with spondyloepiphyseal dysplasia presentation; Kimberley type.

Identification of a frameshift mutation in Osterix in a patient with recessive osteogenesis imperfecta.

Osteogenesis imperfecta, or "brittle bone disease," is a type I collagen-related condition associated with osteoporosis and increased risk of bone fractures. Using a combination of homozygosity mapping and candidate gene approach, we have identified a homozygous single base pair deletion (c.1052delA) in SP7/Osterix (OSX) in an Egyptian child with recessive osteogenesis imperfecta. The clinical findings from this patient include recurrent fractures, mild bone deformities, delayed tooth eruption, normal hearing, and white sclera. OSX encodes a transcription factor containing three Cys2-His2 zinc-finger DNA-binding domains at its C terminus, which, in mice, has been shown to be essential for bone formation. The frameshift caused by the c.1052delA deletion removes the last 81 amino acids of the protein, including the third zinc-finger motif. This finding adds another locus to the spectrum of genes associated with osteogenesis imperfecta and reveals that SP7/OSX also plays a key role in human bone development.

Temtamy preaxial brachydactyly syndrome is caused by loss-of-function mutations in chondroitin synthase 1, a potential target of BMP signaling.

Altered Bone Morphogenetic Protein (BMP) signaling leads to multiple developmental defects, including brachydactyly and deafness. Here we identify chondroitin synthase 1 (CHSY1) as a potential mediator of BMP effects. We show that loss of human CHSY1 function causes autosomal-recessive Temtamy preaxial brachydactyly syndrome (TPBS), mainly characterized by limb malformations, short stature, and hearing loss. After mapping the TPBS locus to chromosome 15q26-qterm, we identified causative mutations in five consanguineous TPBS families. In zebrafish, antisense-mediated chsy1 knockdown causes defects in multiple developmental processes, some of which are likely to also be causative in the etiology of TPBS. In the inner ears of zebrafish larvae, chsy1 is expressed similarly to the BMP inhibitor dan and in a complementary fashion to bmp2b. Furthermore, unrestricted Bmp2b signaling or loss of Dan activity leads to reduced chsy1 expression and, during epithelial morphogenesis, defects similar to those that occur upon Chsy1 inactivation, indicating that Bmp signaling affects inner-ear development by repressing chsy1. In addition, we obtained strikingly similar zebrafish phenotypes after chsy1 overexpression, which might explain why, in humans, brachydactyly can be caused by mutations leading either to loss or to gain of BMP signaling.