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Bone formation is controlled by histone modifying enzymes that regulate post-translational modifications on nucleosomal histone proteins and control accessibility of transcription factors to gene promoters required for osteogenesis. Enhancer of Zeste homolog 2 (EZH2/Ezh2), a histone H3 lysine 27 (H3K27) methyl transferase, is a suppressor of osteoblast differentiation. Ezh2 is regulated by SET and MYND domain-containing protein 2 (SMYD2/Smyd2), a lysine methyltransferase that modifies both histone and non-histone proteins. Here, we examined whether Smyd2 modulates Ezh2 suppression of osteoblast differentiation. Musculoskeletal RNA-seq data show that SMYD2/Smyd2 is the most highly expressed SMYD/Smyd member in human bone tissues and mouse osteoblasts. Smyd2 loss of function analysis in mouse MC3T3 osteoblasts using siRNA depletion enhances proliferation and calcium deposition. Loss of Smyd2 protein does not affect alkaline phosphatase activity nor does it result in a unified expression response for standard osteoblast-related mRNA markers (e.g., Bglap, Ibsp, Spp1, Sp7), indicating that Smyd2 does not directly control osteoblast differentiation. Smyd2 protein depletion enhances levels of the osteo-suppressive Ezh2 protein and H3K27 trimethylation (H3K27me3), as expected from increased cell proliferation, while elevating the osteo-inductive Runx2 protein. Combined siRNA depletion of both Smyd2 and Ezh2 protein is more effective in promoting calcium deposition when compared to loss of either protein. Collectively, our results indicate that Smyd2 inhibits proliferation and indirectly the subsequent mineral deposition by osteoblasts. Mechanistically, Smyd2 represents a functional epigenetic regulator that operates in parallel to the suppressive effects of Ezh2 and H3K27 trimethylation on osteoblast differentiation.

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency caused by genetic defects in the Bruton tyrosine kinase (Btk) gene. XLA is characterized as an antibody deficiency by recurrent bacterial infections, the absence of peripheral B cells, and profound reductions in all immunoglobulin isotypes. This study aims to report the clinical and genetic features of five Iranian patients with XLA. Five male cases with recurrent bacterial infection entered this study based on clinical evaluation and Immunological screening tests. The levels of T-cell receptor excision circle (TREC) and kappa-deleting recombination excision circle (KREC) were also measured in dried blood spot (DBS) samples. Sanger sequencing was applied to PCR products of DNA samples of the patients for genetic studies. All patients were from unrelated families with a mean age of 6.7 years (2.5-11) at the time of diagnosis with 4.8 mean years of delay in diagnosis. The most frequent clinical manifestations were recurrent respiratory infections and arthritis. In these patients, five previously reported mutations were found including four mutations (p.Q496X, p.Q497X, p.R520X, and p.R641H) in the Kinase domain besides one mutation (p.L37P) in the pleckstrin homology (PH) domain. Evaluations of KREC and TREC level in patients’ DBS showed low-to-undetectable copies of KREC (0-2 copies/3.2mm DBS) with normal copies of TREC. As patients with XLA have complete immunoglobulin defects and develop severe and recurrent infections, early diagnosis would be beneficial for the improvement of their quality of life. The study results may provide valuable information for the diagnosis, genetic counseling and prenatal diagnosis for the patients and their family members and emphasize performing KREC as an early diagnostic test in patients with XLA.

Background Merosin-deficient congenital muscular dystrophy (MDC1A) is a rare autosomal recessive genetic disease occurred due to mutations in the LAMA2 gene. This study investigated the molecular genetics of three Iranian MDC1A patients who manifested hypotonia, muscle weakness at birth, elevated levels of creatine kinase, and normal magnetic resonance imaging before the age of six months Methods Peripheral blood samples were collected from three unrelated patients and their families after obtaining informed written consents. Genomic DNA was extracted and sequenced using next-generation sequencing, followed by Sanger confirmation. Results Sequencing results revealed a known missense mutation, c.8665G>A, and two novel heterozygous sequencing variants affecting splicing, c.397-4_c.478del and c.7452-1G>A, in the LAMA2 gene. Reverse transcriptase-PCR analysis showed that a new intronic variant, c.7452-1G>A, produced aberrant splicing pattern in the patient. Conclusion This study expands the mutation spectrum of LAMA2 and assists in the diagnosis, genetic counseling, and prenatal diagnosis of the affected families.

Results Eighty six patients with CMA (3month to 18 yrs) were entered this study Fifty three patients were males (61.1%). Median of age was 2.5 yrs (Mean=3.98) and most of CMA patients was under 2 yrs (45.1 %). Mean of total IgE was 343.39±93.63 (SE)(0.2-5000IU/ml). The symptoms of patients was as following: (respiratory symptoms: 62.8%, Skin symptoms: 56.4%, gastrointestinal symptoms: 19.2% & Anaphylaxis: 13.6%). Totally, positive Specific IgE to cow’s milk protein, a-lactalbumin, casein, b-lactoglobulin and bovin serum albumin were 89.2%, 78.3%, 75%, 63.4%, & 45.5%, respectively. Although a-lactalbumin & casein were the most allergenic protein, mean of specific IgE concentration to blactoglobulin was highest in patients with CMA. There was a significant correlation between positive specific IgE to b-lactalbumin & anaphylaxis (P=0.05) and also between respiratory symptoms and positive specific IgE to casein (P=0.01). There was significant difference between mean of specific IgE to casein between males and females (P=0.001) that was the more frequent in males.