[Application of flat-sided culture tubes during prenatal diagnosis].

OBJECTIVE: To assess the value of using flat-sided culture tubes for preparing chromosomes through chorionic villi (CV) and amniotic fluid (AF) cell cultures during prenatal diagnosis. METHODS: From February to March 2020, 157 CV samples and 147 AF samples subjected to prenatal diagnosis at the Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region were selected as the study subjects. For each sample, one flat-sided tube and one flask culture were set up by following the standard protocols. The methods were evaluated by comparing the cell growth, experimental process, quality of chromosome preparation and costs. RESULTS: The success rates for the culturing of CV and AF samples by the flat-sided culture tube method were 97.45% (153/157) and 97.96% (144/147), respectively. By contrast, the success rates for the conventional flask method were 98.72% (155/157) for CV and 98.64% (145/147) for AF samples. No significant difference was found between the two methods (P > 0.05). The average harvest time required by the flat-sided culture tube method was 8.45 days for CV and 9.43 days for AF cultures, whilst the average harvest time for conventional flask method was 9.05 days and 9.54 days, respectively. The flat-sided culture tube method for CV had required significantly shorter average harvest time than the conventional method (P < 0.001). No statistical significant difference was found in the average harvest time for AF by the two methods (P > 0.05). The conventional culturing method had required three containers with two sample transfers. By contrast, the flat-sided culture tube method was carried out in one tube without any sample transfer. The average total amount of medium used was 3.91 mL for each flat-sided culture tube and 6.26 mL for each conventional flask. CONCLUSION: The flat-sided culture tube method can provide a simple, cost-effective and error-reducing procedure for the CV and AF samples culture during prenatal diagnosis.

Cobalt-Catalyzed Remote Hydroboration of Alkenyl Amines.

We here present a generally applicable cobalt-catalyzed remote hydroboration of alkenyl amines, providing a practical strategy for the preparation of borylamines and aminoalcohols. This method shows broad substrate scope and good functional group tolerance, tolerating a series of alkenyl amines, including alkyl-alkyl amines, alkyl-aryl amines, aryl-aryl amines, and amides. Of note, this protocol is also compatible with a variety of natural products and drug derivatives. Preliminary mechanistic studies suggest that this transformation involves an iterative chain walking and hydroboration sequence.

Enantioselective Rh-Catalyzed Hydroboration of Silyl Enol Ethers.

The asymmetric hydroboration of alkenes has proven to be among the most powerful methods for the synthesis of chiral boron compounds. This protocol is well suitable for activated alkenes such as vinylarenes and alkenes bearing directing groups. However, the catalytic enantioselective hydroboration of O-substituted alkenes has remained unprecedented. Here we report a Rh-catalyzed enantioselective hydroboration of silyl enol ethers (SEEs) that utilizes two new chiral phosphine ligands we developed. This approach features mild reaction conditions and a broad substrate scope as well as excellent functional group tolerance, and enables highly efficient preparation of synthetically valuable chiral borylethers.

Novel compound heterozygous variant of BSCL2 identified by whole exome sequencing and multiplex ligation­dependent probe amplification in an infant with congenital generalized lipodystrophy.

Congenital generalized lipodystrophy (CGL) is a clinically and genetically heterogeneous condition with autosomal recessive inheritance. CGL is classified into four subtypes on the basis of causative genes. This study reported on a 2­month­old male infant diagnosed with CGL with generalized lipoatrophy and skin hyperpigmentation. Whole exome sequencing (WES) identified a heterozygous small insertion (c.545_546insCCG) in Berardinelli­Seip congenital lipodystrophy 2 (BSCL2) that was inherited from the infant's mother. Copy number variation analysis using exome data suggested a heterozygous deletion involving exon 3 that was inherited from the infant's father. This finding was confirmed by multiplex ligation­dependent probe amplification test. Gap­PCR revealed breakpoints and confirmed a 1274 bp heterozygous deletion encompassing exon 3 of BSCL2 (c.213­1081_c.294+111). This deletion is different from the founder 3.3 kb deletion involving exon 3 of BSCL2 in the Peruvian population. An 11­bp microhomology at the breakpoints may mediate the deletion, and its presence indicates the independent origins of the exon 3 deletion between Chinese and Peruvian populations. The present results expanded the mutational spectrum of the BSCL2 gene in the Chinese population and suggested that introns 2 and 3 of BSCL2 are prone to recombination. Thus, exon 3 deletion should be considered for patients with CGL2 when only one BSCL2 variant is detected through WES.

Two novel pathogenic variants of L1CAM gene in two fetuses with isolated X­linked hydrocephaly: A case report.

Hydrocephalus due to aqueductal stenosis (HSAS; Online Mendelian Inheritance in Man #307000) is a rare X­linked, recessively­inherited disease characterized by severe hydrocephaly and occasionally adducted thumbs, in addition to intellectual disability and spasticity in surviving individuals. The present study described two fetuses with severely enlarged ventricles of the brain. The clinical diagnosis of HSAS was made on the basis of family history and sonographic findings. Molecular testing of the L1 cell adhesion molecule (L1CAM) gene revealed two novel hemizygous L1CAM variants, c.998C>T(p.Pro333Leu) and c.2362G>T(p.Val788Phe). The variants affect the highly conserved amino acids which are located in the key domains of the protein (the fourth Ig domain and second FnIII domain, respectively). The two variants were predicted to be 'disease causing' by a number of prediction tools, and have been classified as likely pathogenic following the American College of Medical Genetics and Genomics/Association for Molecular Pathology guidelines. The present study highlights the importance of combining family history, prenatal ultrasonography and molecular testing in the diagnosis of HSAS. The novel variants expand the mutational spectrum of L1CAM gene in the Chinese population, and could be used in genetic counseling, carrier testing of female relatives, and prenatal, as well as preimplantation genetic diagnosis.

[A novel compound heterozygous mutation causing 3-methylcrotonyl-CoA carboxylase deficiency].

OBJECTIVE: To explore the molecular mechanism for a boy suspected with 3-methylcrotonyl-CoA carboxylase deficiency by neonatal screening. METHODS: PCR and Sanger sequencing were used to identify potential mutations of MCCC1 and MCCC2 genes. SIFT and Polyphen-2 software was used to predict the effect of variant on the protein function and conservation of the variant across various species. Human Splicing Finder and Swiss-PdbViewer4.1.0 were applied to analyze the possible mechanism of the variant. RESULTS: For the proband, a compound heterozygous mutation was discovered in the MCCC1 gene, namely c.539G>T (p.G180V) and c.704_711del (p.A235Vfs*4), which were inherited from his father and mother, respectively. The two mutations have disrupted the protein conformation, which in turn may impact the function of MCC protein. CONCLUSION: The compound heterozygous mutations of the MCCC1 gene may contribute to the 3-methylcrotonyl-CoA carboxylase deficiency manifested by the patient.

A novel de novo microdeletion at 17q11.2 adjacent to NF1 gene associated with developmental delay, short stature, microcephaly and dysmorphic features.

BACKGROUND: Microdeletions at 17q11.2 often encompass NF1 gene, is the cause for NF1 microdeletion syndrome. Microdeletion at 17q11.2 without the involvement of NF1 gene is rarely reported. CASE PRESENTATION: Here we reported a patient carrying a novel de novo deletion at 17q11.2 adjacent to NF1 gene, who presented with developmental delay, short stature, postnatal microcephaly, underweight and dysmorphic features including flat facial profile, dolicocephaly, hypertelorism, short philtrum, flat nasal bridge and posteriorly rotated and low set ears. Chromosomal microarray analysis revealed a 1.69 Mb de novo deletion at 17q11.2 adjacent to NF1 gene, which involves 43 RefSeq genes. We compared this with four overlapping deletions at this interval. CONCLUSIONS: A rare de novo microdeletion at 17q11.2 not involving NF1 gene is associated with developmental delay and dysmorphic features. Seven genes, TAOK1, PHF12, NUFIP2, SLC26A4, SEZ6, GIT1 and TRAF4 are possible candidates for the clinical features of our patient. The delineation of this rare deletion and description of associated clinical phenotypes will help to understand the genotype-phenotype correlation of genomic imbalances at this locus.