Human mutation
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Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder caused by cilia and sperm dysmotility. About 12% of cases show perturbed 9+2 microtubule cilia structure and inner dynein arm (IDA) loss, historically termed "radial spoke defect." We sequenced CCDC39 and CCDC40 in 54 "radial spoke defect" families, as these are the two genes identified so far to cause this defect. We discovered biallelic mutations in a remarkable 69% (37/54) of families, including identification of 25 (19 novel) mutant alleles (12 in CCDC39 and 13 in CCDC40). ⋯ A major putative hotspot mutation was identified, CCDC40 c.248delC, as well as several other possible hotspot mutations. Together, these findings highlight the key role of CCDC39 and CCDC40 in PCD with axonemal disorganization and IDA loss, and these genes represent major candidates for genetic testing in families affected by this ciliary phenotype. We show that radial spoke structures are largely intact in these patients and propose this ciliary ultrastructural abnormality be referred to as "IDA and microtubular disorganisation defect," rather than "radial spoke defect."
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Generalized pustular psoriasis (GPP) is a rare, potentially life threatening, and aggressive form of psoriasis, which is characterized by sudden onset with repeated episodic skin inflammation leading to pustule formation. Familial GPP is known to be caused by recessively inherited mutations in the IL36RN gene, which encodes interleukin 36 receptor antagonist (IL-36Ra). In this article, we performed mutation analysis of the IL36RN gene in 14 Japanese patients with GPP, and identified mutations in two of these patients analyzed. ⋯ In vitro studies in cultured cells showed impaired expression of the p. Thr123Arg mutant IL-36Ra protein, which failed to antagonize the IL-36 signaling pathway. Our data further underscore the critical role of IL36RN in pathogenesis of GPP.
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Cerebral palsy (CP) is a permanent disorder, affecting 2-3 per 1,000 live born children, disturbing movement and posture. Spastic limbs affects about 70-80% of the CP children, and this group is the target of our study. CP is considered a multifactorial condition believed to be provoked by, for example, preterm birth, infection during pregnancy, neural disorders, and genetics, to mention some. ⋯ In addition, fitting a Tobit regression model for each protein and each SNP in the respective gene loci, we estimated three regression coefficients corresponding three different effects of the genetic variation on the protein level. Intriguingly, two IL18 loci SNPs (rs549908:A>C and rs1290349:C>A) showed a protective effect against spastic CP, and interestingly both were associated to a decreased epidemiological expression of IL-18 protein. By joining protein data to genetic information, we have provided new data suggesting IL18's involvement in the pathogenesis of spastic CP.
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Aicardi-Goutières syndrome (AGS) is a rare inherited autoimmune disease caused by mutations in genes encoding the RNase H2 subunits A, B, and C; the DNase three prime repair exonuclease 1 (TREX1); and sterile alpha motif (SAM) domain and HD domain-containing protein 1 (SAMHD1). Using unbiased affinity purification coupled to protein mass spectrometry, we identify SAMHD1 as a nucleic-acid-binding protein displaying a preference for RNA over DNA. ⋯ Furthermore, we show that although wild-type SAMHD1 displays almost exclusive nuclear localization, 11 of 12 SAMHD1 mutants show at least partial mislocalization to the cytosol. Overall, these data suggest that SAMHD1 has a role in the nucleus that, if disrupted by mutation, leads to cytosolic accumulation of SAMHD1 and autoimmune disease.