Novel biallelic variants affecting the OTU domain of the gene OTUD6B associate with severe intellectual disability syndrome and molecular dynamics simulations.

Intellectual developmental disorder with dysmorphic facies, seizures, and distal limb anomalies (IDDFSDA) is an autosomal recessive multisystem disorder caused by compound heterozygous or homozygous variants in the gene OTUD6B. Herein, we describe novel pathogenic compound heterozygous variants in OTUD6B identified via whole-exome sequencing in an index case exhibited the severe IDDFSDA phenotype. The potential pathogenicity of the novel frameshift and missense variants in the index case was investigated using in silico tools. The truncating frameshift variant in one allele was predicted to undergo degradation via nonsense-mediated decay of the mRNA molecule. To predict the severity of the damage to the protein caused by the missense variant in the other allele and its effects on phenotypic severity was further investigated together with a previously reported first homozygous missense variant in the same domain in another patient with a less severe IDDFSDA phenotype using structural modeling and molecular dynamics (MD) simulations for the first time. Based on these analyzes, it is anticipated that Tyr216Cys in the earlier reported case with less severe IDDFSDA will lead to localized destabilization, whereas Ile274Arg in the presented index case with the severe IDDFSDA phenotype will lead to significant distortion in the overall fold of OTUD6B. Our findings suggest that compound LOF and ultrarare missense variants may be contribute to the underlying variability expressivity associated with this disorder. In conclusion, our findings support that the clinical severity could be related with the predicted functional severity of the variations in OTUD6B. However, additional functional studies are required.

OCLN gene variants identified in three patients with severe neurodevelopmental disorder associated with epilepsy, intellectual disability and malformation of cortical development.

Homozygous OCLN variants have been reported in patients with band-like calcification with simplified gyration and polymicrogyria (BLC-PMG) which is characterized by microcephaly, intracranial calcification and severe developmental delay. The OCLN gene encodes the integral membrane protein, occludin. Herein, we report three additional cases with homozygous OCLN variants that were identified via Trio-WES in two consanguineous unrelated families. We detected a previously reported frameshift variant in two cases in Family 1 and a novel missense variant in a case in Family 2. The potential pathogenicity of both variants in the index cases was investigated using in silico tools, and both variants were determined to be rare and predicted to be pathogenic. All of the presented cases exhibited clinical features in common with earlier reported patients, such as severe intellectual disability, microcephaly, polymicrogyria, epilepsy, hypotonia and severe developmental delay. On the other hand, in addition to the common phenotypic features, our two cases in Family 1 showed features similar to those previously reported in cases from two Turkish families carrying the same frameshift variant, such as renal failure. We herein expand the spectrum of OCLN gene variants with a description of an additional novel homozygous missense variant. The frameshift variant in Turkish cases may thus be a phenotype associated with renal failure in addition to the core phenotype associated with other OCLN gene variants, and such variants could be important for rapid molecular diagnosis and treatment. The frameshift variant in Turkish cases might also be investigated for both a potential founder effect and mutational hot spot.

Cryptosporidium spp. during chemotherapy: a cross-sectional study of 94 patients with malignant solid tumor.

BACKGROUND: Cryptosporidium spp. is a protozoan parasite that infects many vertebrate animals, including humans. Since Cryptosporidium spp. can cause chronic life-threatening diarrhea and severe malabsorption in immunocompromised patients, we investigated the prevalence of this parasite among patients undergoing chemotherapy for malignant solid tumors. OBJECTIVE: Investigate the prevalence of Cryptosporidium spp. in stool samples. DESIGN: Cross-sectional. SETTING: Tertiary care. PATIENTS AND METHODS: Stool samples were collected from adult patients with malignant solid tumors receiving chemotherapy and diarrhea. Cryptosporidium spp. prevalence was determined using Ziehl-Neelsen staining, ELISA, and real-time PCR targeting of the COWP gene. MAIN OUTCOME MEASURE: The prevalence of Cryptosporidium spp. in patients undergoing chemotherapy for malignant solid tumors. SAMPLE SIZE: 94 RESULTS: The prevalence was 2.1% (2/94), 5.3% (5/94), and 5.3% (5/94) as detected by Ziehl-Neelsen staining, real-time PCR and ELISA, respectively. The prevalence reached 8.5% (8/94) using all results obtained from the three methods. Among eight positive stool samples, four were positive by at least two different methods (Ziehl-Neelsen staining-ELISA or ELISA-real-time PCR) whereas the remaining four were positive by either ELISA or real-time PCR. CONCLUSION: These findings show the risk of cryptosporidiosis in cancer patients and the necessity to use at least two diagnostic methods during the diagnosis of cryptosporidiosis to reach more accurate and trustworthy results. LIMITATIONS: Further studies with a larger sample size are recommended. CONFLICT OF INTEREST: None.