Examining resting state functional connectivity and frequency power analysis in adults who stutter compared to adults who do not stutter.

Introduction: Stuttering is a speech disorder characterized by impaired connections between brain regions involved in speech production. This study aimed to investigate functional connectivity and frequency power during rest in adults who stutter (AWS) compared to fluent adults (AWNS) in the dorsolateral prefrontal cortex (DLPFC), dorsolateral frontal cortex (DLFC), supplementary motor area (SMA), motor speech, angular gyrus (AG), and inferior temporal gyrus (ITG). Materials and methods: Fifteen AWS (3 females, 12 males) and fifteen age- and sex-matched AWNS (3 females, 12 males) participated in this study. All participants were native Persian speakers. Stuttering severity in the AWS group was assessed using the Persian version of the Stuttering Severity Instrument Fourth Edition (SSI-4). Resting-state electroencephalography (EEG) was recorded for 5 min while participants sat comfortably with their eyes open. We analyzed frequency band power across various frequency bands and investigated functional connectivity within the specified speech region. Results: Significant between-group differences were found in band powers including alpha, beta, delta, theta, and gamma, specifically in the premotor, SMA, motor speech, and frontal regions. AWS also showed increased coherence between the right motor speech region compared to controls. We demonstrate that the proposed hierarchical false discovery rate (FDR) method is the most effective for both simulations and experimental data. In the expected regions, this method revealed significant synchrony effects at an acceptable error rate of 5%. Conclusion: The results highlight disrupted functional connectivity in AWS at resting state, particularly in speech-related and associated areas. Given the complex neurological basis of developmental stuttering, robust neural markers are closely linked to this phenomenon. These markers include imbalanced activity within brain regions associated with speech and motor functions, coupled with impaired functional connectivity between these regions. The cortico-basal ganglia-thalamo-cortical system governs the dynamic interplay between cortical regions, with SMA as a key cortical site. It is hypothesized that the aberrant resting state functional connectivity will impact the language planning and motor execution necessary for fluent speech. Examining resting-state metrics as biomarkers could further elucidate the neural underpinnings of stuttering and guide intervention.

Molecular Basis of α-Thalassemia in Iran

Alpha-thalassemia (α-thal) is probably the most prevalent monogenic condition in the world. Deletions are the most common types of mutations in α-thal, followed by point mutations and small insertion/deletion. In the context of national screening program for prevention of thalassemia and hemoglobinopathies in Iran, α-thal carriers have come to more attention. Therefore, the frequency and distribution of α-globin mutations in various regions of the country have been studied in recent years. A comprehensive search was performed in PubMed, Scopus, and national databases for finding reports on mutation detection in α-thal carriers and HbH disease with Iranian origin. The mutation data of 10849 α-thal carriers showed that -α3.7 and α-5NT were the most common deletional and nondeletional mutations, respectively. In HbH disease cases, the -α3.7/--MED was the most prevalent genotype. Overall, 42 different mutations have been identified in α-globin cluster reflecting the high heterogeneity of the mutations in Iranian populations.

Molecular Characterization of δ-Thalassemia in Iran.

δ-Thalassemia (δ-thal) (OMIM #142000) resulting from mutations on the HBD gene usually has no clinical consequences. However, it may cause the misdiagnosis of ß-thalassemia (ß-thal) carriers by lowering the Hb A2 level to the normal range. Therefore, a study for δ-thal should be considered as a step in the detection of at-risk couple in our region. The aim of the present study was to characterize the mutations of the HBD gene in ß-thal carriers with normal Hb A2 levels, and also in normal individuals with Hb A2 of less than 2.0%. Four ß-thal carriers with normal Hb A2 and 39 individuals with Hb A2 of less than 2.0% were enrolled. Genomic DNA was extracted by the salting out method and the HBD gene was investigated by polymerase chain reaction (PCR) and direct DNA sequencing. Hb A2-Yialousa (HBD: c.82 G > T) was the most common variant found in the HBD gene, but the following mutations were also found: Hb A2-NYU (HBD: c.39 T > A), Hb A2-Coburg (HBD: c.350 G > A), Hb A2-Etolia (HBD: c.257 T > C), Hb A2-Fitzroy (HBD: c.428 C > A) and the δ-IVS-I-5 (G > T) (HBD: c.92 + 5 G > T). One case was a compound heterozygote for δ-IVS-I-5/Hb A2-Fitzroy. The results of this single center study suggest that the mutations in the HBD gene in the Iranian population are heterogeneous and should be considered in genetic counseling of families.

Prenatal diagnosis of ß-thalassemia in twin pregnancies in Iran.

OBJECTIVE: Prenatal diagnosis of ß-thalassemia carrier couples has helped to prevent bearing affected children. Among 177 couples referred to our laboratory for prenatal diagnosis, 14 mothers had twin pregnancies.  METHODS: By using direct and indirect methods, we determined their mutations and linkage analysis using polymorphic markers (restriction fragment length polymorphism [RFLP]).  RESULTS:  It was shown that in five families both fetuses were heterozygote carriers. In another five families, one fetus was normal and the other one was carrier. In two families, one fetus was affected and the other one was heterozygous carrier; in one case one fetus was affected and the other one was homozygote normal. In the last family both fetuses were homozygote normal. If all fetuses were fraternal then one would expect to see seven homozygote normal and the same number affected, and 14 carriers. CONCLUSION: Our results indicated that at least in cases where both fetuses had identical genotypes, then they may be identical twins. Molecular testing indeed showed that in three cases the twins were identical. Another point is that in three cases, one of the twin fetuses was affected and the other one was either normal or heterozygote in which only the affected fetuses were aborted by the specialist.

Co-inheritance of hemoglobin D and ß-thalassemia traits in three Iranian families: clinical relevance.

Here we report the result of three cases referred to our lab that had a combination of ß-thalassemia and hemoglobin D (Hb D) traits. These individuals had no symptoms of profound anemia and hematological indices were similar to that of a ß-thalassemia heterozygote. In all three cases, the Hb D level was elevated and no HbA was detected electrophoretically. The electrophoresis pattern suggested that all cases were homozygotes for Hb D. PCR followed by digestion with EcoRI and sequencing of the ß-globin gene confirmed the presence of Cd 121 GAA>CAA in the heterozygous form with another ß-globin mutation. In all cases, the mutations in the ß-globin gene were detected by ARMS PCR technique and they were either IVSII-I or IVSI-5. Hematological studies of the family members showed that thalassemia which caused the mutations and Hb D were in the trans position.

A novel polymorphism causes a different restriction pattern by RsaI in the beta-globin gene cluster: application in prenatal diagnosis.

beta-Thalassemia (beta-thal) is a major health problem in Iran and the incidence of carriers is around 3-4%. The disease is caused by heterogeneous mutations in the beta-globin gene and is characterized by hypochromic microcytic anemia. The human beta-globin complex spans a region of 70 kb and contains over 20 restriction fragment length polymorphisms (RFLPs). At least nine RFLP markers including RsaI/beta in the beta-globin gene cluster have been routinely exploited for prenatal diagnosis. Here, we report a novel polymorphism upstream of the beta-globin gene characterized by RsaI digestion. Sequencing of a fragment containing this area showed a nucleotide change (T>C) at position -223 upstream of the beta-globin gene. This change could interfere with precise interpretation of the RsaI digestion pattern in linkage analysis and prenatal diagnosis of beta-thal.