Clinical characteristics and identification of novel CNOT1 variants in three unrelated Chinese families with Vissers-Bodmer Syndrome.

Vissers-Bodmer Syndrome, an autosomal dominant disease, is a neurodevelopmental disorder characterized by global developmental delay, intellectual disability, hypotonia and autistic features with a highly variable phenotype. It is caused by variants in the CCR4-NOT transcription complex, subunit 1 gene (CNOT1). However, the pathophysiologic mechanism of the Vissers-Bodmer Syndrome remains unclear. Notably, this syndrome has not been previously reported in the Chinese. In this study, we utilized whole exome sequencing to identify three novel variants in the CNOT1 gene, encompassing one frameshift variant and two missense variants, in three Chinese patients mainly presenting with developmental delay, intellectual disability and/or autism. Interestingly, three patients exhibited novel manifestations including spina bifida occulta, horse-shoe kidney and café-au-lait spot. The frameshift variant, p.Gly172Alafs*5, occurring de novo, leading to a premature stop codon in the protein, was classified into pathogenic. Two missense variants c.3451A > G (p.Asn1151Asp) and c.557C > T (p.Ser186Phe) were predicted to be deleterious by multiple prediction algorithms with high conservation among a variety of species. Additionally, three-dimensional structure modeling and predicting indicated the substitution of the mutated amino acids would decrease the stability of CNOT1 protein. Given that CNOT1 is a relatively novel disease gene, we evaluated the gene-disease validity following ClinGen Standard Operating Procedure. The existing evidence substantiates a "Definitive" level of gene-disease relationship. The genetic findings provide a reliable basis for the genetic counseling of the family reproduction. Moreover, our results expand the genetic and phenotypic spectrum of CNOT1-related Vissers-Bodmer Syndrome.

Application of a Multiplex Ligation-Dependent Probe Amplification-Based Next-Generation Sequencing Approach for the Detection of Pathogenesis of Duchenne Muscular Dystrophy and Spinal Muscular Atrophy Caused by Copy Number Aberrations.

Both Duchenne muscular dystrophy (DMD; OMIM no. 310200) and spinal muscular atrophy (SMA; OMIM no. 253300/253550/253400/271150) are genetic disorders characterized by progressive muscle degeneration and weakness. Genetic copy number aberrations in the pathogenetic genes DMD and SMN1 lead to alterations in functional proteins, resulting in DMD and SMA, respectively. Multiplex ligation-dependent probe amplification (MLPA) has become a standard method for the detection of common copy number aberrations (CNAs), including DMD and SMN1 deletions, both of which are associated with poor clinical outcomes. However, traditional MLPA assays only accommodate a maximum of 60 MLPA probes per test. To increase the number of targeted sequences in one assay, an MLPA-based next-generation sequencing (NGS) assay has been developed that is based on the standard MLPA procedure, allows high-throughput screening for a large number of fragments and samples by integrating additional indices for detection, and can be analyzed on all Illumina NGS platforms.

Cytopenia: a report of haplo-cord transplantation in twin brothers caused by a novel germline GATA1 mutation and family survey.

Cytopenia due to the abnormal regulation of GATA1 could manifest as varying degrees of thrombocytopenia and/or anemia and more severely in male children than in female children. Here, we describe the case of pancytopenic and transfusion-dependent twin brothers at our center whose bone marrow puncture revealed low bone marrow hyperplasia. Whole-exome sequencing revealed that the twins had a new germline GATA1 mutation (nm_002049: exon 3:c.515 T >C:p.F172S), which confirmed the diagnosis of GATA1 mutation-related pancytopenia. The mutation was inherited from their mother, who was heterozygous for the mutation. Sanger sequencing verified the pathogenicity of the mutation. Further family morbidity survey confirmed that GATA1 mutation-related pancytopenia is an X-linked recessive genetic disorder. We developed haploid hematopoietic stem cell transplantation programs for twins, with the father as the only donor, and finally, the hematopoietic reconstruction was successful. Although they experienced acute graft-versus-host disease, hemorrhagic cystitis, and a viral infection in the early stage, no abnormal manifestations or transplant-related complications were observed 3 months after transplantation. Through hematopoietic stem cell transplantation technology for one donor and two receptors, we eventually cured the twins. The p.F172S variant in the new germline GATA1 mutation may play an essential role in the pathogenesis of GATA1 mutation-related cytopenia.

Case Report: Eosinophilic gastritis with pyloric stenosis in immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome.

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare X-linked recessive immunodeficiency caused by mutations in the forkhead box protein 3 (FOXP3) gene. IPEX is characterized by the onset of intractable diarrhea, type 1 diabetes mellitus (T1DM), and eczema in the early stages of life. The typical clinic triad for IPEX is not always seen. Here, we report a 15-year-old male patient with atypical IPEX syndrome complicated with severe eosinophilic gastritis (EG) and pyloric stenosis. The patient had noticeable eczema during the first year of life and had a history of food allergies. At the age of 3 years, the patient was diagnosed with EG, Helicobacter pylori (HP) infection, pyloric stenosis with recurrent vomiting, and failure to thrive. The patient did not respond to long-term symptomatic treatments in the following years, including methylprednisolone, proton pump inhibitors (PPI), L-glutamine and sodium gualenate granules, anti-HP therapy, and balloon dilation. At the age of 12 years, the patient received surgical interventions, including a laparoscopic jejunostomy feeding tube placement, gastrojejunal anastomosis bypass, and jejunal-jejunal end-to-side anastomosis. Intractable diarrhea and T1DM were not present in the patient. At the age of 14 years, the patient was diagnosed with IPEX syndrome due to a c.748-750del (p.Lys250del) mutation in the leucine zipper domain of the FOXP3 protein. The patient underwent matched sibling peripheral blood hematopoietic stem cell transplantation (HSCT) and showed good evolution after 3 months of HSCT. In summary, this case report provides information of unusual gastrointestinal findings in IPEX syndrome and highlights the need for increased awareness and early diagnosis of IPEX syndrome, which is vital for improving the patient's outcome.

Clinical characteristics and genetics of ten Chinese children with PRRT2-associated neurological diseases.

Background: Proline-rich transmembrane protein 2 (PRRT2) plays an important role in the central nervous system and mutations in the gene are implicated in a variety of neurological disorders. This study aimed to summarize the clinical characteristics and gene expression analysis of neurological diseases related to the PRRT2 gene and explore the clinical characteristics, therapeutic effects, and possible pathogenic mechanisms of related diseases. Methods: We enrolled 10 children with PRRT2 mutation-related neurological diseases who visited the Children's Hospital affiliated with the Shanghai Jiaotong University School of Medicine/Shanghai Children's Hospital between May 2017 and February 2022. Video electroencephalography (VEEG), cranial imaging, treatment regimens, gene results, and gene expression were analyzed. Genetic testing involved targeted sequencing or whole-exome genome sequencing (WES). We further analyzed the expression and mutation conservation of PRRT2 and synaptosome-associated protein 25 (SNAP25) in blood samples using quantitative polymerase chain reaction (qPCR) and predicted the protein structure. Summary analysis of the reported gene maps and domains was also performed. Results: Ten children with PRRT2 gene mutations were analyzed, and 4 mutations were identified, consisting of 2 new (c.518A > C, p.Glu173 Ala; c.879 + 112G > A, p.?) and two known (c. 649 dup, p. Arg217Profs * 8; c. 649 del, p. Arg217Glufs * 12) mutations. Among these mutations, one was de novo(P6), and three could not be determined because one parent refused genetic testing. The clinical phenotypes were paroxysmal kinesigenic dyskinesia (PKD), benign familial infantile epilepsy (BFIE), epilepsy, infantile spasms, and intellectual disability. The qPCR results showed that PRRT2 gene expression levels were significantly lower in children and parent carriers than the control group. The SNAP25 gene expression level of affected children was significantly lower (P ≤ 0.001) than that of the control group. The mutation sites reported in this study are highly conserved in different species. Among the various drugs used, oxcarbazepine and sodium valproate were the most effective. All 10 children had a good disease prognosis, and 8 were completely controlled with no recurrence, whereas 2 had less severe and fewer seizures. Conclusion: Mutation of PRRT2 led to a significant decrease in its protein expression level and that of SNAP25, suggesting that the mutant protein may lead to the loss of its function and that of related proteins. This mutation site is highly conserved in most species, and there was no significant correlation between specific PRRT2 genotypes and clinical phenotypes. Asymptomatic carriers also have decreased gene expression levels, suggesting that more factors are involved.

Segawa syndrome caused by TH gene mutation and its mechanism.

Dopa-responsive dystonia (DRD), also known as Segawa syndrome, is a rare neurotransmitter disease. The decrease in dopamine caused by tyrosine hydroxylase (TH) gene mutation may lead to dystonia, tremor and severe encephalopathy in children. Although the disease caused by recessive genetic mutation of the tyrosine hydroxylase (TH) gene is rare, we found that the clinical manifestations of seven children with tyrosine hydroxylase gene mutations are similar to dopa-responsive dystonia. To explore the clinical manifestations and possible pathogenesis of the disease, we analyzed the clinical data of seven patients. Next-generation sequencing showed that the TH gene mutation in three children was a reported homozygous mutation (c.698G>A). At the same time, two new mutations of the TH gene were found in other children: c.316_317insCGT, and c.832G>A (p.Ala278Thr). We collected venous blood from four patients with Segawa syndrome and their parents for real-time quantitative polymerase chain reaction analysis of TH gene expression. We predicted the structure and function of proteins on the missense mutation iterative thread assembly refinement (I-TASSER) server and studied the conservation of protein mutation sites. Combined with molecular biology experiments and related literature analysis, the qPCR results of two patients showed that the expression of the TH gene was lower than that in 10 normal controls, and the expression of the TH gene of one mother was lower than the average expression level. We speculated that mutation in the TH gene may clinically manifest by affecting the production of dopamine and catecholamine downstream, which enriches the gene pool of Segawa syndrome. At the same time, the application of levodopa is helpful to the study, diagnosis and treatment of Segawa syndrome.

Two novel heterozygous truncating variants in NR4A2 identified in patients with neurodevelopmental disorder and brief literature review.

Pathogenic variants in the nuclear receptor superfamily 4 group A member 2 (NR4A2) cause an autosomal dominant neurodevelopmental disorder with or without seizures. Here, we described two patients presenting with developmental delay, language impairment, and attention-deficit hyperactivity disorder. Trio-based whole exome sequencing revealed two novel heterozygous variants, c.1541-2A > C and c.915C > A, in NR4A2. Both variants were identified as de novo and confirmed by Sanger sequencing. In vitro functional analyses were performed to assess their effects on expression of mRNA or protein. The canonical splicing variant c.1541-2A > C caused aberrant splicing, leading to the retention of intron 7 and a truncated protein due to an early termination codon within intron 7 with decreased protein expression, while the variant c.915C > A was shown to result in a shorter protein with increased expression level unexpectedly. The clinical and genetic characteristics of the previously published patients were briefly reviewed for highlighting the potential link between mutations and phenotypes. Our research further confirms that NR4A2 is a disease-causing gene of neurodevelopmental disorders and suggests alterations in different domains of NR4A2 cause various severity of symptoms.

Induced pluripotent stem cells (SHCDNi006-A cells) isolated from the peripheral blood mononuclear cells of a five-month-old Chinese girl with the heterozygous missense mutation (c.2800 G>A) in the KCNT1 gene.

Epilepsy of infancy with migrating focal seizures (EIMFS) is a kind of epileptic encephalopathy with high genetic heterogeneity. The most common pathogenic gene for EIMFS is potassium sodium-activated channel subfamily T member 1 (KCNT1). Using Sendai virus-mediated reprogramming, we established an induced pluripotent stem cell (iPSC) line from the peripheral blood mononuclear cells (PBMCs) of a five-month-old Chinese girl with heterozygous missense mutation (c.2800 G>A) in the KCNT1 gene. The iPSCs were stable during amplification, expressed pluripotent genes, maintained a normal karyotype, and showed characteristics of the three germs layers in an in vitro differentiation assay.

Compound heterozygous mutations of NDUFV1 identified in a child with mitochondrial complex I deficiency.

BACKGROUND: Mitochondrial complex I deficiency (MCID) is the most common biochemical defect identified in childhood with mitochondrial diseases, mainly including Leigh syndrome, encephalopathy, macrocephaly with progressive leukodystrophy, hypertrophic cardiomyopathy and myopathy. OBJECTIVE: To identify genetic cause in a patient with early onset autosomal recessive MCID. METHODS: Trio whole-exome sequencing was performed and phenotype-related data analyses were conducted. All candidate mutations were confirmed by Sanger sequencing. RESULTS: Here we report a child of Leigh syndrome presented with global developmental delay, progressive muscular hypotonia and myocardial damage. A missense mutation c.118C > T (p.Arg40Trp) and a previously reported mutation c.1157G > A (p.Arg386His) in NDUFV1 have been identified as compound heterozygous in the patient. The mutation p.Arg386His is closely associated with the impairment of 4Fe-4S domain and this mutation has been reported pathogenic. The c.118C > T mutation has not been reported in ClinVar and HGMD database. In silico protein analyses showed that p.Arg40 is highly conserved in a wide range of species, and the amino acid substitution p.Trp40 largely decreases the stability of NDUFV1. In addition, the mutation has not been detected in the Asian populations and it was predicted to be deleterious by numerous prediction tools. CONCLUSION: This research expands the mutation spectrum of NDUFV1 and substantially provides an early and accurate diagnosis basis of MCID, which would benefit subsequently effective genetic counseling and prenatal diagnosis for future reproduction of the family.

Generation of an induced pluripotent stem cell line from an Ohtahara syndrome patient with the hemizygous mutation p.Q503Afs*28 (c.1507_1508del) in the ARX gene.

Aristaless-related homeobox (ARX)-related disorders are recessive X-linked intellectual disability disorders. We encountered a patient with a hemizygous mutation (c.1507_1508del) showing intellectual disability, early-onset epileptic encephalopathy and Ohtahara syndrome. The patient had female genitals, but an XY karyotype. We established an induced pluripotent stem cell (iPSC) line from the peripheral blood mononuclear cells (PBMCs) of a six-month Chinese child with a hemizygous mutation (c.1507_1508del) in ARX. The PBMCs were reprogrammed with Sendai viral vectors. The iPSCs showed stable amplification, pluripotency-related gene expression, and trilineage differentiation potential. Karyotype analysis of the iPSCs showed 23 pairs of chromosomes with normal structure and sex chromosome is XY.

Case report: Osteo-oto-hepato-enteric syndrome caused by UNC45A deficiency.

Background: Recently, UNC45 myosin chaperone A (UNC45A) deficiency was identified as a cause of osteo-oto-hepato-enteric syndrome (O2HE) characterized by congenital diarrhea, neonatal cholestasis, deafness, and bone fragility. To date, only a few O2HE cases have been reported in the literature. Case presentation: Here, we present a child from China diagnosed with O2HE with novel compound heterozygous variants in UNC45A. The patient suffered with neonatal jaundice, cholestasis, and intractable diarrhea after birth. Laboratory tests revealed highly elevated levels of total serum bilirubin (TB), direct bilirubin (DB), and total bile acid (TBA). The patient was managed with ursodeoxycholic acid (UDCA)-based treatments, and the clinical symptoms and abnormal liver functions were significantly relieved. The patient's hearing was normal, and no sign of bone fragility was observed. Exome sequencing (ES) identified novel compound heterozygote variants c.292C>T (p.Arg98Trp)/c.2534-2545del (p.Leu845-Met848del) in UNC45A, which were inherited from her mother and father, respectively. Both variants are predicted to be deleterious by in silico predictors. Conclusion: We present an O2HE child from China with novel compound heterozygous variants in UNC45A. Our patient's clinical manifestations were less severe than those of the previous reported cases, which expands the clinical spectrum of O2HE.

Allogeneic Hematopoietic Stem Cell Transplantation for PEX1-Related Zellweger Spectrum Disorder: A Case Report and Literature Review.

Zellweger spectrum disorder (ZSD) is a heterogeneous group of autosomal recessive disorders characterized by a defect in peroxisome formation and attributable to mutations in the PEX gene family. Patients with ZSD have profound neurologic impairments, including seizures, severe retardation, and dysmorphic features, and poor prognosis. Currently, there is no specific, effective treatment. Here, we investigated the effects of allogeneic hematopoietic stem cell transplantation (allo-HSCT) on PEX1-related ZSD. The suspected clinical proband was first diagnosed at the Department of Neurology of our hospital. The proband died soon after diagnosis, and his family was studied. We found that a brother had the same genetic alterations, and he was diagnosed with Infantile Refsum disease (IRD) as the mildest form of ZSD. We implemented treatment with allo-HSCT, at the request of the child's parents. After transplantation, we observed significant improvements in the clinical manifestations, very-long-chain fatty acids, and brain MRI. The patient has recovered well and not showed any abnormal clinical manifestations after 2 years of follow-up. We have achieved satisfactory short-term results in the treatment of ZSD-IRD with allo-HSCT. Long-term follow-up and observation will be performed to determine the long-term prognosis.

Generation and characterization of an iPSC line (SHCMDLi001-A) from a 12-year-old Chinese Han patient with TRAF7 syndrome and of an iPSC line (SHCMDLi002-A) from a control individual.

Mutations in TRAF7 cause developmental delay and cardiac, facial, digital anomalies. c.1964G > A variant was most recurrent, suggesting its essentiality of pathogenicity. Further studies to determine the underlying mechanism of c.1964G > A variant are warranted. But no patient-specific cellular models have been generated. Here, we generated an iPSC line with c.1964G > A variant (SHCMDLi001-A) and a line from healthy individual (SHCMDLi002-A). Characterization of SHCMDLi001-A and SHCMDLi002-A demonstrated these iPSCs are free of exogenous reprogramming genes, expressed pluripotency markers, exhibited a normal karyotype and were potential of three germ layer differentiation. These lines provide a valuable resource for studying disease-causing mechanism of TRAF7 variant.

Novel Mutations of the ALMS1 Gene in Patients with Alström Syndrome.

Objective Alström syndrome is an autosomal recessive genetic disease caused by a mutation in the ALMS1 gene. Alström syndrome is clinically characterized by multisystem involvement, including sensorineural deafness, cone-rod dystrophy, nystagmus, obesity, insulin resistance, type 2 diabetes and hypogonadism. The diagnosis is thus challenging for patients without this characteristic set of clinical symptoms. We explored the effectiveness of whole-exome sequencing in the diagnosis of Alström syndrome. Methods A girl with symptoms of Alström syndrome was tested and diagnosed with the disease by whole-exome sequencing. Results Whole-exome sequencing revealed two novel variants, c.6160_6161insAT: p.Lys2054Asnfs*21 (exon 8) and c.10823_10824 delAG:p.Glu 3608Alafs*9 (exon16) in the ALMS1 gene, leading to premature termination codons and the domain of ALMS1 protein. Blood sample testing of her asymptomatic parents revealed them to be heterozygous carriers of the same mutations. Assembly showed that the mutations on both alleles were located in conserved sequences. A review of the ALMS1 gene nonsense mutation status was performed. Conclusion We herein report two novel variants of the ALMS1 gene discovered in a Chinese Alström syndrome patient that expand the mutational spectrum of ALMS1 and provided new insight into the molecular mechanism underlying Alström syndrome. Our findings add to the current knowledge concerning the diagnosis and treatment of Alström syndrome.

Case Report: A Novel Compound Heterozygous Mutation in IL-10RA in a Chinese Child With Very Early-Onset Inflammatory Bowel Disease.

Very early-onset inflammatory bowel disease (VEO-IBD) is defined as IBD diagnosed in children younger than 6 years of age. VEO-IBD is often associated with a monogenic etiology or primary immune deficiency. Here, we report the case of a 7-month-old Chinese girl diagnosed with VEO-IBD who had a variant in the interleukin-10 receptor A (IL-10-RA) gene. The patient presented with recurrent fevers, abdominal pain, diarrhea, perianal abscesses, and oral ulcers. Whole-exome sequencing (WES) identified a novel compound heterozygote mutation, c.395T>G (p.Leu132Arg)/ex.1del (p.?), in the IL-10RA gene of the patient. The missense mutation c.395T>G (p.Leu132Arg) was inherited from her mother, and ex.1del (p.?) was inherited from her father. Neither mutation has been reported previously. The IL-10RA function of the patient was defective, as demonstrated by a failure of signal transducer and activator of transcription 3 (STAT3) activation in peripheral blood mononuclear cells (PBMCs) stimulated with recombinant IL-10. The patient underwent matched unrelated peripheral blood hematopoietic stem cell transplantation (HSCT), and the clinical manifestations were dramatically improved. In summary, we identified a novel compound heterozygote mutation, c.395T>G (p.Leu132Arg)/ex.1del (p.?), in IL-10RA that caused VEO-IBD in a Chinese child, which further expands the mutational spectrum of IL-10RA.

De novo variants in WDR45 underlie beta-propeller protein-associated neurodegeneration in five independent families.

BACKGROUND: Beta-propeller protein-associated neurodegeneration (BPAN) is a rare, X-linked dominant neurodegenerative disease mainly characterized by developmental delay, intellectual disability, epilepsy in childhood and dystonia, parkinsonism, dementia in adulthood. BPAN is caused by variants in WD repeat domain 45(WDR45), which is characterized by iron accumulation in the basal ganglia, however, it may be atypical in early brain MRI. METHODS: Whole exome sequencing was performed for five parents-offspring trios and phenotype-driven data analyses were conducted. All candidate variants were confirmed by Sanger sequencing. RESULTS: Here, we report five independent children presented variable degree of developmental delay, intellectual disability, and/or epilepsy. Five de novo variants of WDR45 including four novel truncating variants (one splicing variant, two nonsense variants, and one frameshift variant) were identified. Although their early brain MRI showed no obvious iron accumulation, multifocal spikes, or polyspikes in electroencephalograms (EEG) were observed in four patients. CONCLUSION: Our study reports four patients with new variants in WDR45, which expands the mutation spectrum of WDR45. In addition, our findings provide an early and precise diagnosis basis of BPAN, which is helpful for accurate genetic counseling and prenatal diagnosis.

Spectrum of RB1 Germline Mutations and Clinical Features in Unrelated Chinese Patients With Retinoblastoma.

Retinoblastoma (Rb) is a primary intraocular malignant tumor that occurs primarily in children, and results from loss-of-function mutations in the RB transcriptional corepressor 1 (RB1) gene. Genetic testing forms the basis of genetic counseling for affected families, as well as for clinical management of this disease. The aim of this study was to identify germline RB1 mutations and correlate the identified mutations with the clinical features of Rb patients. Genomic DNA was isolated from peripheral blood of 180 unrelated Rb patients and their parents (118 unilaterally and 62 bilaterally affected probands). Mutations in the RB1 gene, including the promoter region and exons 1-27 with flanking intronic sequences, were identified by Sanger sequencing. The samples with negative sequencing results were further subjected to methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) to detect gross deletions or duplications. Sixty-three distinct mutations were identified in 75 of the 180 (41.7%) probands. Of the 75 patients carrying RB1 mutations, 56 developed bilateral Rb, while 19 developed unilateral Rb. The total detection rates for bilateral and unilateral Rb were 90.3% (56/62) and 16.1% (19/118), respectively. Among the 75 patients, the spectrum of mutation types comprised 29.3% (22/75) nonsense mutations, 22.7% (17/75) splicing mutations, 17.3% (13/75) small insertions/deletions, 16.0% (12/75) large deletions/duplications, and 13.3% (10/75) missense mutations, while only 1% (1/75) of the mutations were in the promoter region of the RB1 gene. Age at diagnosis was significantly different (p < 0.01) between patients with positive and negative test results for germline RB1 mutations. A c.2359C > T mutation (p.R787X) was identified in identical twins, but one child was affected bilaterally and the other unilaterally. Of the five patients with deletion of the entire RB1 gene, the deletion of two patients was inherited from unaffected parents. In conclusion, in this study, we provide a comprehensive spectrum of RB1 germline mutations in Chinese Rb patients, and describe the correlations among RB1 mutations, age at diagnosis, and laterality; moreover, we report that the clinical features of individuals carrying an identical mutation in the RB1 gene were highly variable, indicating that the pathogenesis of Rb is more complicated than currently believed.

A de novo MAPRE2 variant in a patient with congenital symmetric circumferential skin creases type 2.

BACKGROUND: Congenital symmetric circumferential skin creases (CSCSC) was initially described five decades ago. Exome sequencing has recently revealed the genetic etiology of CSCSC. Pathogenic variants in TUBB (OMIM# 191130) and MAPRE2 (OMIM# 605789) have been linked to CSCSC1 (OMIM# 156610) and CSCSC2 (OMIM# 616734), respectively, in an autosomal dominant manner. Four pathogenic variants in MAPRE2 have been previously reported to be associated with CSCSC2. METHODS: Whole-exome sequencing (WES) has been performed and an in-house pipeline was used to conduct a phenotype-driven data analysis. All candidate variants were confirmed by Sanger sequencing. RESULTS: Here we report a 2-year-old boy characterized by absent expressive speech, normal to mild over growth, facial dysmorphic features, remarkable circumferential skin creases on both forearms and ankles. WES disclosed a de novo missense MAPRE2 variant, c.518G>A (p.Arg173Gln), as the molecular cause of this complex phenotype. We described detailed clinical characterization of this patient and compared the available clinical data of individuals with MAPRE2 variants to demonstrate the phenotypic spectrum. CONCLUSION: Our study reports the first patient of Asian origin with CSCSC2 due to a pathogenic mutation of MAPRE2 and expands the clinical and genetic spectrum of CSCSC2.

[Mutation analysis of two pedigrees with suspected oculocutaneous albinism].

OBJECTIVE: To analyze the clinical presentation and gene of 2 pedigrees with suspected oculocutaneous albinism(OCA), and provide basis for clinical classification, genetic counseling and prenatal diagnosis. METHODS: Variants were identified using next-generation sequencing(NGS) and confirmed by Sanger sequencing in 2 pedigrees with suspected OCA. The pathogenicity of the variants was analyzed according to the American College of Medical Genetics and Genomics (ACMG) standard. RESULTS: Two compound heterozygous mutations of TYR and OCA2 genes were identified respectively in 2 pedigrees with suspected OCA. The mutation of c.819+3insATATGCC in TYR and the mutation of c.1870G>C in OCA2 are first reported in this study. The pathogenicity analysis shows that two novel mutations are likely pathogenic by combination of prediction of SIFT, Polyphen-2 and Human Splicing Finder. CONCLUSION: The findings of this study expand the mutational spectrum of OCA. Compound heterozygous mutations in the TYR and OCA2 gene may be responsible for clinical manifestations of 2 pedigrees with suspected OCA.

A multiplex ligation­dependent probe amplification­based next­generation sequencing approach for the detection of copy number variations in the human genome.

The aim of the present study was to describe a multiplex ligation­dependent probe amplification (MLPA)­based next­generation sequencing (NGS) assay that exhibited a significantly higher efficiency in detecting copy number variations (CNVs) and known single­nucleotide variants, compared with traditional MLPA. MLPA polymerase chain reaction products were used to construct a library with indexed adapters, which was subsequently tested on an NGS platform, and the resulting data were analyzed by a series of analytical software. The reads from each probe reflected genetic variations in the target regions, and fragment differentiation was based on the specific base composition of the sequences, rather than fragment length, which was determined by capillary electrophoresis. The results of this approach were not only consistent with the MLPA results following capillary electrophoresis, but also coincided with the CNV results from the single­nucleotide polymorphism array chip. This method allowed high­throughput screening for the number of fragments and samples by integrating additional indices for detection. Furthermore, this technology precisely and accurately performed large­scale detection and quantification of DNA variations, thereby serving as an effective and sensitive method for diagnosing genetic disorders caused by CNVs and known single­nucleotide variations. Notably, MLPA­NGS circumvents the problems associated with the inaccuracies of NGS in CNV detection due to the use of target sequence capture.