Screening and genotyping of thalassemia in Ningbo / 中华地方病学杂志

Objective:To study the genotyping of thalassemia in Ningbo population and provide a reference basis for future prevention and control of thalassemia in Ningbo.Methods:Patients with suspected thalassemia attending Ningbo Women and Children's Hospital from January 2019 to March 2022 were selected for the study, and DNA was extracted from dried blood spot specimens by collecting peripheral blood, and detection of thalassemia hotspot variants was performed by fluorescence PCR melting curve analysis combined with Sanger sequencing or multiplex ligation-dependent probe amplification (MLPA).Results:A total of 2 680 cases were included in the patients with suspected thalassemia, and 1 426 cases of thalassemia gene carriers were detected, with an overall detection rate of 53.2%. Among them, 595 cases (41.7%) were α-thalassemia, with -- SEA/αα, αα/-α 3.7 and -- SEA/-α 3.7 being more common; 807 cases (56.6%) were β-thalassemia, with β IVS-Ⅱ-654/β N, β CD41-42/β N and β CD17/β N being more common; 24 cases (1.7%) were αβ-combined thalassemia. Among them, six rare variant types were included, including fusion gene (Fusion), -- FIL, HBA2:c.376C>T, CD8/9(+G), IVS-Ⅰ-2(T>C) and IVS-Ⅱ-1(G>A), all of which were reported for the first time in Ningbo. Conclusion:Among suspected thalassemia patients in Ningbo, the detection rate of thalassemia is high, and the types of gene variants are complex, so the awareness of thalassemia gene testing for anemic patients should be raised.

Genetic variation of thalassemia in children in Ningbo City and its correlation with erythrocyte parameters / 中华地方病学杂志

Objective:To explore the type and composition of thalassemia gene variation in children in Ningbo City, and to analyze its correlation with erythrocyte parameters.Methods:From January 2019 to December 2020, 785 children who underwent thalassemia gene testing in Ningbo Women and Children's Hospital were selected as the retrospective research subjects to analyze the type and composition of thalassemia gene variation in local children. A total of 238 thalassemia gene mutation carriers and 100 healthy children (control group) who underwent physical examination during the same period were selected for routine blood test to analyze the correlation between thalassemia gene mutation types and serological indexes.Results:Among the 785 children who underwent thalassemia gene testing, 571 were confirmed as carriers of thalassemia gene mutation, with a detection rate of 72.7%, including 228 cases of α-thalassemia, 337 cases of β-thalassemia, and 6 cases of αβ-complex type thalassemia. It covered 17 variant types and 25 gene combinations. There were significant differences in red blood cell count (RBC), hematokrit (HCT), hemoglobin concentration (Hb), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV) and red blood cell distribution width (RDW) between the control, α-thalassemia and β-thalassemia groups ( H/ F = 125.03, 86.24, 141.06, 192.99, 121.46, 198.63, 178.06, P < 0.001). And there were statistically significant differences in HCT, Hb, MCH, MCV and RDW among the four common genotypes (-- SEA/αα, β IVS-Ⅱ-654/β N, β CD41-42/β N and β CD17/β N) in this test ( F = 5.03, 3.34, 6.24, 10.33, 6.83, P < 0.05). Conclusion:The genotypes of children with thalassemia in Ningbo City are diverse, and the erythrocyte parameters are different among different genotypes.

Enlarged multicystic dysplastic kidneys with oligohydramnios during infancy caused by NPHP3 gene mutation / 中华医学遗传学杂志

OBJECTIVE@#To explore the clinical features and genomic abnorm ality of a fetus enlarged multicystic dysplastic kidneys with oligohydramnios caused by NPHP3 gene mutation.@*METHODS@#The fetuse was found to have multicystic dysplastic kidneys with oligohydramnios upon ultrasonography during the second trimester. Following induced abortion, fetal tissue was collected for the extraction of DNA, chromosomal microarray analysis (CMA) and whole exome sequencing (WES). Sanger sequencing was used to verify the suspected variants in the family.@*RESULTS@#Antenatal ultrasound examination at 19 weeks showed "polycystic" kidneys with Oligohydramnios. Delivery was by induced labour because of the critically low amniotic fluid volume. Testing of CMA was normal. WES showed a compound heterozygous mutation of c.1817G>A, p.W606X; c.432dupA, p.E145Rfs*18 mutations are novel mutations in this study.@*CONCLUSION@#The research may further expand the NPHP3 gene mutation spectrum. Enlarged multicystic dysplastic kidneys with oligohydramnios caused by NPHP3 gene mutation at least include one or two splice site mutation, frameshift mutation or nonsense mutation foetal poor prognosis.

Analysis of TUBB2B gene variant in a fetus with complex cortical dysplasia with other brain malformations-7 / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a fetus with dysgenesis of corpus callosum and other brain malformations.@*METHODS@#Whole exome sequencing was carried out for the fetus and its parents. Suspected pathogenic variants were verified by Sanger sequencing.@*RESULTS@#A novel de novo missense variant c.758T>A (p.L253Q) of the TUBB2B gene was identified, which was unreported previously. Based on the guidelines from the American College of Medical Genetics, the c.758T>A variant was predicted to be likely pathogenic. Bioinformatics analysis predicted that the leucine at position 253 was highly conserved among various species, and the c.758T>A variant may impact the formation of hydrogen bonds between Leu253 and Asp249 and Met257 residues, which in turn may affect the combination of GTP/GDP and function of the TUBB2B protein.@*CONCLUSION@#The c.758T>A variant of the TUBB2B gene probably underlay the fetal malformations in this Chinese family. Above discovery has enriched the spectrum of TUBB2B gene variants and provided a basis for genetic counseling and prenatal diagnosis.

Study on newborn screening for Duchenne muscular dystrophy and diagnostic strategy / 中华医学遗传学杂志

OBJECTIVE@#To establish a newborn screening system for Duchenne muscular dystrophy (DMD) through assessment of MM isoenzyme of creatine kinase (CK-MM) activity.@*METHODS@#The CK-MM level was detected using dry blood spot filter paper from 10 252 male newborns. The results were grouped based on their gestational age, sampling time and intervals between the experiments. The threshold value for CK-MM necessitating genetic testing was determined. Next-generation sequencing (NGS) was carried out for those with a CK-MM value over the threshold, and the result was verified by multiplex ligation-dependent probe amplification (MLPA).@*RESULTS@#Based on the result of non-parametric rank sum test, the median CK-MM concentration has increased with the gestational age, and was inversely correlated with the age of the newborns among unaffected specimens. CK-MM on dry blood spot filter paper can be stable for 14 days at 2-8℃. Statistical analysis of CK-MM value of the 10 252 neonates suggested that the threshold may be set as 700 ng/mL. Exonic deletions were found in 2 confirmed cases, whose CK-MM level was greater than 2000 ng/mL.@*CONCLUSION@#Detection of CK-MM in dry blood spot filter paper has provided an effective method for newborn screening of DMD. This simple and inexpensive method can be used for large-scale screening, which is of great value to the early intervention and treatment of the disease.