Application of next generation sequencing in the screening of monogenic diseases in China,2021:a consensus among Chinese newborn screening experts

Newborn screening(NBS)refers to a maternal and newborn healthcare technology,in which special examinations of congenital and genetic diseases that could seriously impact the health of newborns,are implemented during the neonatal period to provide early diagnosis and treatment[1].With a history of more than 60 years,NBS has advanced greatly due to technological progress resulting in significant improvement in the number of diseases covered by NBS and in screening efficiency[2-7].

A multicenter prospective study of next-generation sequencing-based newborn screening for monogenic genetic diseases in China

Background Newborn screening(NBS)is an important and successful public health program that helps improve the long-term clinical outcomes of newborns by providing early diagnosis and treatment of certain inborn diseases.The develop-ment of next-generation sequencing(NGS)technology provides new opportunities to expand current newborn screening methodologies.Methods We designed a a newborn genetic screening(NBGS)panel targeting 135 genes associated with 75 inborn disorders by multiplex PCR combined with NGS.With this panel,a large-scale,multicenter,prospective multidisease analysis was conducted on dried blood spot(DBS)profiles from 21,442 neonates nationwide.Results We presented the positive detection rate and carrier frequency of diseases and related variants in different regions;and 168(0.78%)positive cases were detected.Glucose-6-Phosphate Dehydrogenase deficiency(G6PDD)and phenylketonuria(PKU)had higher prevalence rates,which were significantly different in different regions.The positive detection of G6PD variants was quite common in south China,whereas PAH variants were most commonly identified in north China.In addi-tion,NBGS identified 3 cases with DUOX2 variants and one with SLC25A13 variants,which were normal in conventional NBS,but were confirmed later as abnormal in repeated biochemical testing after recall.Eighty percent of high-frequency gene carriers and 60%of high-frequency variant carriers had obvious regional differences.On the premise that there was no significant difference in birth weight and gestational age,the biochemical indicators of SLC22A5 c.1400C>G and ACADSB c.1165A>G carriers were significantly different from those of non-carriers.Conclusions We demonstrated that NBGS is an effective strategy to identify neonates affected with treatable diseases as a supplement to current NBS methods.Our data also showed that the prevalence of diseases has significant regional charac-teristics,which provides a theoretical basis for screening diseases in different regions.

Surgical management and molecular diagnosis of persistent Müllerian duct syndrome in Chinese patients

Persistent Müllerian duct syndrome(PMDS)is a rare clinically and genetically overlapping disorder caused by mutations in the anti-Müllerian hormone(AMH)gene or the anti-Müllerian hormone receptor type 2(AMHR2)gene.Affected individuals present uterus and tubes in normally virilized males and are discovered unexpectedly during other surgeries.Since it is rare and complex,a definitive clinical diagnosis can be missed,and there are no guidelines regarding how to deal with the uterus.In the present study,exome sequencing and Sanger verification were performed for causal variants in 12 PMDS patients.Preoperative diagnoses were made by positive exome sequencing in 8 patients.Of them,7 patients evoked on the basis of ultrasound indicating bilateral testes on the same side of the body.Twelve different AMH variants(2 frameshift/nonsense,1 deletion,8 missense,and 1 in-frame)in 9 patients and 6 different AMHR2 variants(5 missense and 1 splicing)in 3 patients were identified.Seven variants were classified as“pathogenic”or“likely pathogenic”,and 4 of them were novel.All but two patients with AMH defects showed low serum AMH concentrations,but all patients with AMHR2 defects showed elevated AMH levels.During surgery,an abnormal vas deferens was observed in half of the patients.Eight patients underwent orchidopexy with uterine preservation.Of them,2 patients presented complications including irreducible cryptorchidism,and 3 patients developed Müllerian remnant cysts.Three patients underwent subtotal hysterectomy.Of them,one patient had complication of injury to the vas deferens,and one had hemorrhage after operation.This is the first report of PMDS involving a large Chinese population.The present study not only expands the variation spectrum but also provides clinical experience about the management of the uterus.

FMR1 allele frequencies in 51,000 newborns:a large-scale population study in China

Background Fragile X syndrome(FXS).caused by CGG-repeat expansion in FMR1 promoter,is one of the most common causes of mental retardation.Individuals with full mutation and premutation alleles have a high risk of psychophysiological disorder and of having affected offspring.Frequencies of FMR1 alleles in general newborns have been reported in Caucasians but have not been investigated in the large-scale population in the mainland of China.Methods The sizes of FMRI CGG-repeats were analyzed in 51,661 newborns(28,114 males and 23,547 females)and also in a cohort of 33 children diagnosed with developmental delay using GC-rich polymerase chain reaction(PCR)and triple repeat primed PCR.Results The frequency of CGG repeats>100 was 1/9371 in males and 1/5887 in females,and the frequency of CGG repeats>54 was 1/1561 in males and 1/1624 in females.FMRJ full mutation and premutation were identified in 27.27%of children who had Ages and Stages Questionnaire scores less than two standard deviations from the cutoff value.Conclusions Our study revealed the prevalence of FXS in China and improved the sample databases of FXS,suggesting that the prevalence of FXS in Chinese is higher than estimated previously and that FXS screening can be advised to high-risk families.