The Frequency of Common Deafness-Associated Variants Among 3,555,336 Newborns in China and 141,456 Individuals Across Seven Populations Worldwide.

OBJECTIVES: Genetic screening can benefit early detection and intervention for hearing loss. The frequency of common deafness-associated variants in general populations is highly important for genetic screening and genetic counseling tailored to different ethnic backgrounds. We aimed to analyze the frequency of common deafness-associated variants in a large population-based Chinese newborn cohort and to explore the population-specific features in diverse populations worldwide. DESIGN: This population-based cohort study analyzed the frequency of common deafness-associated variants in 3,555,336 newborns in the Chinese Newborn Concurrent Hearing and Genetic Screening cohort. Participants were newborn infants born between January 2007 and September 2020. Limited genetic screening for 20 variants in 4 common deafness-associated genes and newborn hearing screening were offered concurrently to all newborns in the Chinese Newborn Concurrent Hearing and Genetic Screening cohort. Sequence information of 141,456 individuals was also analyzed from seven ethnic populations from the Genome Aggregation Database for 20 common deafness-related variants. Statistical analysis was performed using R. RESULTS: A total of 3,555,326 Chinese neonates completed the Newborn Concurrent Hearing and Genetic Screening were included for analysis. We reported the distinct landscape of common deafness-associated variants in this large population-based cohort. We found that the carrier frequencies of GJB2 , SLC26A4 , GJB3 , and MT-RNR were 2.53%, 2.05%, 0.37%, and 0.25%, respectively. Furthermore, GJB2 c.235delC was the most common variant with an allele frequency of 0.99% in the Chinese newborn population. We also demonstrated nine East-Asia-enriched variants, one Ashkenazi Jewish-enriched variant, and one European/American-enriched variant for hearing loss. CONCLUSIONS: We showed the distinct landscape of common deafness-associated variants in the Chinese newborn population and provided insights into population-specific features in diverse populations. These data can serve as a powerful resource for otolaryngologists and clinical geneticists to inform population-adjusted genetic screening programs for hearing loss.

A novel delins (c.773_819+47delinsAA) mutation of the PCCA gene associated with neonatal-onset propionic acidemia: a case report.

BACKGROUND: Propionic acidemia (PA)(OMIM#606054) is an inborn error of branched-chain amino acid metabolism, caused by defects in the propionyl-CoA carboxylase (PCC) enzyme which encoded by the PCCA and PCCB genes. CASE PRESENTATION: Here we report a Chinese neonate diagnosed with suspected PA based on the clinical symptoms, gas chromatography-mass spectrometry (GC/MS), and brain imaging tests. Targeted next-generation sequencing (NGS) was performed on the proband. We detected only one heterozygous recurrent nonsense variant (c.937C > T, p.Arg313Ter) in the PCCA gene. When we manually checked the binary alignment map (BAM) diagram of PCCA gene, we found a heterozygous deletion chr13:100915039-100915132delinsAA (c.773_819 + 47delinsAA) (GRCh37.p13) inside the exon 10 in the PCCA gene. The results were validated by Sanger sequencing and qPCR method in the family: the variant (c.937C > T, p.Arg313Ter) was in the maternal allele, and the delins was in the paternal allele. When the mother was pregnant again, prenatal diagnosis was carried out through amniocentesis at 18 weeks gestation, the fetus carried neither of the two mutations. After birth, newborn screening was undertaken, the result was negative. CONCLUSIONS: We identified a recurrent c.937C > T and a novel c.773_819 + 47delinsAA mutations in the PCCA gene, which may be the genetic cause of the phenotype of this patient. Our findings expanded the spectrum of causative genotype-phenotype of the PCCA gene. For the cases, the NGS results revealed only a heterozygous mutation in autosomal recessive disease when the gene is associated with phenotypes, it is necessary to manually check the BAM diagram to improve the detection rate. Targeted NGS is an effective technique to detect the various genetic lesions responsible for the PA in one step. Genetic testing is essential for genetic counselling and prenatal diagnosis in the family to avoid birth defects.

Nationwide population genetic screening improves outcomes of newborn screening for hearing loss in China.

PURPOSE: The benefits of concurrent newborn hearing and genetic screening have not been statistically proven due to limited sample sizes and outcome data. To fill this gap, we analyzed outcomes of newborns with genetic screening results. METHODS: Newborns in China were screened for 20 hearing-loss-related genetic variants from 2012 to 2017. Genetic results were categorized as positive, at-risk, inconclusive, or negative. Hearing screening results, risk factors, and up-to-date hearing status were followed up via phone interviews. RESULTS: Following up 12,778 of 1.2 million genetically screened newborns revealed a higher rate of hearing loss by three months of age among referrals from the initial hearing screening (60% vs. 5.0%, P < 0.001) and a lower rate of lost-to-follow-up/documentation (5% vs. 22%, P < 0.001) in the positive group than in the inconclusive group. Importantly, genetic screening detected 13% more hearing-impaired infants than hearing screening alone and identified 2,638 (0.23% of total) newborns predisposed to preventable ototoxicity undetectable by hearing screening. CONCLUSION: Incorporating genetic screening improves the effectiveness of newborn hearing screening programs by elucidating etiologies, discerning high-risk subgroups for vigilant management, identifying additional children who may benefit from early intervention, and informing at-risk newborns and their maternal relatives of increased susceptibility to ototoxicity.

Panel-based NGS reveals disease-causing mutations in hearing loss patients using BGISEQ-500 platform.

Hearing loss is a highly heterogeneous disease presented with various phenotypes. Genetic testing of disease-causing mutations plays an important role in precise diagnosis and fertility guidance of heredity hearing loss. Here we reported an effective method employing target enrichment and BGISEQ-500 platform to detect clinically relevant alterations for heredity hearing patients in a single assay.In this study, we designed an array based chip, containing 127 genes related to hearing loss. Then we conducted targeted next-generation sequencing toward 58 patients to make a precise diagnosis using BGISEQ-500 platform.We successfully detected disease-causing mutations in 77.59% (45/58) of the patients with hearing loss. Finally, a total of 62 disease-causing mutations were identified, including 31 missense, 17 Indel, 11 splicing, 2 synonymous, and 1 copy number variant. 58.06% (36/62) of which has never been reported before.To our knowledge, this is the first report using BGISEQ-500 platform to investigate both syndromic and nonsyndromic hearing loss in the Chinese population. The results showed that this method can greatly assist and enhance hearing loss diagnosis and improve molecular diagnostics outcome.

Study of the effects of polymerized porcine hemoglobin (pPolyHb) in an acute anemia rat model.

The objective of this study was to investigate the recovery ability of polymerized porcine hemoglobin (pPolyHb) in a rat model of acute anemia caused by normovolemic hemodilution (ANH). After the ANH procedure, rats were infused with either pPolyHb or red blood cells. The results showed pPolyHb could carry a sufficient amount of oxygen to the tissues to maintain normal aerobic metabolism and hemodynamic stability, without any significant toxic effects on renal and liver function according to pathological, and biochemical analysis. The data suggest pPolyHb may be a good candidate for the treatment of acute anemia in future clinical trials.

Effects of resuscitation with polymerized porcine hemoglobin (pPolyHb) on hemodynamic stability and oxygen delivery in a rat model of hemorrhagic shock.

The objective of this study was to evaluate the effects of polymerized porcine hemoglobin (pPolyHb) on hemodynamic stability and oxygen delivery in a rat model of hemorrhagic shock. Rats underwent controlled hemorrhage, resulting in the loss of 65% of their blood volume in 90 minutes. The results showed that pPolyHb was superior to hetastarch and saline, and similar to whole blood, in restoring hemodynamic stability and reversing anaerobic metabolism caused by hemorrhage. Furthermore, pPolyHb improved oxygen supply and increased blood oxygen content. These data suggest that pPolyHb can be effective in improving tissue perfusion under conditions of severe hemorrhagic shock.

The effect of pPolyHb on hemodynamic stability and mesenteric microcirculation in a rat model of hemorrhagic shock.

The effects of polymerized porcine hemoglobin (pPolyHb) on hemodynamic stability and maintenance of mesenteric microvascular function were explored in a rat model of hemorrhagic shock (HS). Following controlled hemorrhage, rats were infused with equal volumes of either pPolyHb, hetastarch (HES), or red blood cell (RBC). The results showed that pPolyHb was superior to HES and RBC in restoring hemodynamic stability and reversing anaerobic metabolism. We observed a reduction in the diameter of mesenteric microvasculature after HS. Resuscitation with pPolyHb and RBC was able to restore the diameters of the venules and arterioles, whereas HES failed to restore the diameters during the observation period.

Study of the inflammatory response of immunocytes to polymerized porcine hemoglobin (pPolyHb).

Polymerized porcine hemoglobin (pPolyHb), which was synthesized from chemically modified porcine hemoglobin, can carry and deliver oxygen to tissues in addition to restoring intravascular volume. Assessment of the inflammatory response generated in the host is a part of the overall safety evaluation of pPolyHb. In this study, we measured the levels of IL-1ß, IL-10, and CD11b/CD18 in response to pPolyHb stimulation, both in vivo (in rats) and in vitro. Our results suggest that the levels of these indicators are not statistically changed by pPolyHb, indicating that pPolyHb is not immunotoxic to cells and animals in this respect.