A novel variant in the FLCN gene in a Chinese family with Birt-Hogg-Dubé syndrome.

BACKGROUND: This study aimed to identify disease-causing variants within a Chinese family affected by Birt-Hogg-Dubé syndrome (BHDS), which arises from an autosomal dominant inheritance pattern attributed to variants in the folliculin (FLCN) gene, recognized as a tumor suppressor gene. METHODS: A Chinese proband diagnosed with BHDS due to renal tumors underwent next-generation sequencing (NGS), revealing a novel variant in the FLCN gene. Sanger sequencing was subsequently performed on blood samples obtained from family members to confirm the presence of this variant. RESULTS: A novel germline frameshift variant (NM_144997.5:c.977dup) was identified in five individuals among the screened family members, marking the first report of this variant. Additionally, a somatic frameshift variant (NM_144997.5:c.1252del) was detected in the renal tumors of the proband. No variant was detected in unaffected family members. CONCLUSIONS: A novel heterozygous variant was identified in exon 9 of the FLCN gene, which broadens the spectrum of FLCN variants. We recommend that molecular analysis of the FLCN gene be performed in patients with suspected BHDS and their families.

MHC heterozygosity limits T cell receptor variability in CD4 T cells.

αß T cell receptor (TCR) V(D)J genes code for billions of TCR combinations. However, only some appear on peripheral T cells in any individual because, to mature, thymocytes must react with low affinity but not high affinity with thymus expressed major histocompatibility (MHC)/peptides. MHC proteins are very polymorphic. Different alleles bind different peptides. Therefore, any individual might express many different MHC alleles to ensure that some peptides from an invader are bound to MHC and activate T cells. However, most individuals express limited numbers of MHC alleles. To explore this, we compared the TCR repertoires of naïve CD4 T cells in mice expressing one or two MHC alleles. Unexpectedly, the TCRs in heterozygotes were less diverse that those in the sum of their MHC homozygous relatives. Our results suggest that thymus negative selection cancels out the advantages of increased thymic positive selection in the MHC heterozygotes.

Prenatal diagnosis of familial 3p26.3p25.3 deletion in a pregnancy associated with a favorable fetal outcome and asymptomatic carrier parent and family members in three generations.

OBJECTIVE: We present prenatal diagnosis of familial 3p26.3p25.3 deletion in a pregnancy associated with a favorable fetal outcome and asymptomatic carrier parent and family members in three generations. CASE REPORT: A 35-year-old, gravida 2, para 1, woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age and the carrier of distal 3p deletion. She was phenotypically normal, and there was no family history of congenital anomalies. Amniocentesis revealed a karyotype of 46,XY,del(3)(p26.1). Repeat amniocentesis at 21 weeks of gestation revealed a karyotype of 46,XY,del(3)(p25.3). Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes showed the result of arr 3p26.3p25.3 (117,735-8,709,972) × 1.0 [GRCh37 (hg19)] with an 8.59-Mb deletion of 3p26.3p25.3 encompassing 14 OMIM genes of CHL1, CNTN6, CNTN4, IL5RA, TRNT1, CRBN, SETMAR, SUMF1, ITPR1, BHLHE40, ARL8B, GRM7, LMCD1 and SSUH2. Cytogenetic analysis of parental bloods revealed a karyotype of 46,XX,del (3) (p25.3) in the mother and 46,XY in the father. The woman's 69-year-old mother and her 2-year-old elder son carried the same aberrant chromosome of 3p25.3→p26.3 deletion by conventional cytogenetic analysis but manifested no phenotypic abnormality. aCGH analysis of the peripheral bloods showed that the woman's mother and her elder son had the same 8.59-Mb deletion of 3p26.3p25.3. The woman was advised to continue the pregnancy. At 39 weeks of gestation, a 3040-g healthy male baby was delivered. When follow-up at age 2½ years, the neonate was normal in development and showed no apparent phenotypic abnormality. CONCLUSION: Distal 3p deletion of 3p26.3p25.3 involving the OMIM genes from CHL1 to SSUH2 can be associated with no apparent phenotypic abnormality.

Case report: An adolescent female with anosmic hypogonadotropic hypogonadism, intellectual disability, and papillary thyroid carcinoma: heterozygous deletion of TCF12.

Background: Isolated hypogonadotropic hypogonadism is a heterogeneous clinical entity. There is a growing list of molecular defects that are associated with hypogonadotropic hypogonadism (HH). TCF12, a recently identified molecular defect, causes craniosynostosis and is suggested to be used as a biomarker for prognosis in various cancer types. Recently, TCF12 variants were shown in a cohort with HH. Case presentation: A 15.3 years old female patient was referred to the endocrinology clinic for obesity. She had been gaining weight from mid-childhood. She had her first epileptic seizure at the age of 15.1 years and mildly elevated thyroid autoantibodies were detected during evaluation for etiology of seizures. She had not experienced menarche yet. She was operated for left strabismus at the age of 7 years. School performance was poor and she was receiving special education. Tanner stage of breast was 1 and pubic hair was 3. The endocrine workup revealed hypogonadotropic hypogonadism. Also, the Sniffin' Sticks test detected anosmia. Thyroid ultrasonography was performed due to the mildly elevated thyroid autoantibodies, and thyroid nodules with punctate calcifications were detected. Total thyroidectomy and central lymph node dissection were performed regarding the cytological findings of the nodules and multicentric papillary thyroid carcinoma with no lymph node metastasis was detected on pathology specimens. Regarding the phenotypic features of the patients, whole exome sequencing was performed and heterozygous deletion of exon 1 and exon 6-8 in TCF12 was detected. Conclusion: Haploinsufficiency of TCF12 causes anosmic HH. Probably due to the incomplete penetrance and variable expressivity of the disease, patients could display variable phenotypic features such as intellectual disability, developmental delay, and craniosynostosis. Further description of new cases with TCF12 variations could enhance our understanding of craniosynostosis and its potential link to Kallmann syndrome associated with this gene.

[Carrier screening for 223 monogenic diseases in Chinese population: a multi-center study in 33 104 individuals].

OBJECTIVE: To investigate the epidemiological characteristics and mutation spectrum of monogenic diseases in Chinese population through a large-scale, multicenter carrier screening. METHODS: This study was conducted among a total of 33 104 participants (16 610 females) from 12 clinical centers across China.Carrier status for 223 genes was analyzed using high-throughput sequencing and different PCR methods. RESULTS: The overall combined carrier frequency was 55.58% for 197 autosomal genes and 1.84% for 26 X-linked genes in these participants.Among the 16 669 families, 874 at-risk couples (5.24%) were identified.Specifically, 584 couples (3.50%) were at risk for autosomal genes, 306(1.84%) for X-linked genes, and 16 for both autosomal and X-linked genes.The most frequently detected autosomal at-risk genes included GJB2(autosomal recessive deafness type 1A, 393 couples), HBA1/HBA2(α-thalassemia, 36 couples), PAH (phenylketonuria, 14 couples), and SMN1(spinal muscular atrophy, 14 couples).The most frequently detected X-linked at-risk genes were G6PD (G6PD deficiency, 236 couples), DMD (Duchenne muscular dystrophy, 23 couples), and FMR1(fragile X syndrome, 17 couples).After excluding GJB2 c.109G>A, the detection rate of at-risk couples was 3.91%(651/16 669), which was lowered to 1.72%(287/16 669) after further excluding G6PD.The theoretical incidence rate of severe monogenic birth defects was approximately 4.35‰(72.5/16 669).Screening for a battery of the top 22 most frequent genes in the at-risk couples could detect over 95% of at-risk couples, while screening for the top 54 genes further increased the detection rate to over 99%. CONCLUSION: This study reveals the carrier frequencies of 223 monogenic genetic disorders in the Chinese population and provides evidence for carrier screening strategy development and panel design tailored to the Chinese population.In carrier testing, genetic counseling for specific genes or gene variants can be challenging, and the couples need to be informed of these difficulties before testing and provided with options for not screening these genes or gene variants.

[Pedigree Analysis and Molecular Mechanism Study of Hereditary Glanzmann Thrombasthenia Caused by Compound Heterozygous Mutation of the ITGA2B Gene].

Objective: The phenotype and genotype of a pedigree with Glanzmann thrombasthenia caused by compound heterozygous mutation in the ITGA2B gene and its molecular pathogenesis were explored. Methods: The platelet aggregation rate of the proband and his family was detected by using a platelet aggregation test with adenosine diphosphate, collagen, epinephrine, arachidonic acid, and ristocetin. The expression levels of CD41 (αⅡb), CD61 (ß3), and CD42b (GPⅠb) on the platelet surface was detected by flow cytometry. Gene sequencing technology was used for the genetic identification of the family. RT-PCR was used in the detection of mRNA splicing, and qRT-PCR was used in detecting the relative mRNA level of the ITGA2B gene. Bioinformatics analysis was used to evaluate the pathogenicity of mutation sites and their effects on protein structure and function. The expressions of total αⅡb and ß3 in platelets were analyzed by Western blot. Results: Except ristocetin, the other four inducers could not induce platelet aggregation in the proband. Flow cytometry showed that the expression levels of αⅡb and ß3 were only 0.25% and 9.76%, respectively, on the platelet surface of the proband, whereas GPⅠb expression was relatively normal. The expression levels of glycoproteins in the other family members were almost normal. c.480C>G and c.2929C>T mutations were detected in the proband through gene sequencing. The c.480C>G mutation was inherited from his mother, and the c.2929C>T mutation was inherited from his father. The RT-PCR and sequencing results showed that the c.480C>G mutation caused mRNA splicing in the proband and his mother, resulting in the deletion of 99 bases in c.476G-574A (p.S160-S192). qRT-PCR showed that the c.2929C>T variant reduced the mRNA level of the ITGA2B gene in the proband and his father. Bioinformatics analysis suggested that the c.480C>G mutation might form a binding sequence with hnRNP A1 protein and generate the 5'SS splice site. The three-dimensional structural model of the αⅡb subunit showed that the ß-propeller domain of the p.S160-S192 deletion lost two ß-strands and one α-helix in blade 2. The c.2929C>T nonsense mutation caused premature translation termination and produced a truncated protein with the deletion of p.R977-E1039, including the cytoplasmic domain, transmembrane domain, and a ß chain of the extracellular Calf-2 domain. The total αⅡb expression of the proband was absent, and the relative expression of ß3 was 11.36% of the normal level. Conclusion: The compound heterozygous mutation c.480C>G in exon 4 and c.2929C>T in exon 28 of the ITGA2B gene probably underlies Glanzmann thrombasthenia in this pedigree.

Concurrent of compound heterozygous variant of a novel in-frame deletion and the common hypomorphic haplotype in TBX6 and inherited 17q12 microdeletion in a fetus.

BACKGROUND: TBX6, a member of the T-box gene family, encodes the transcription factor box 6 that is critical for somite segmentation in vertebrates. It is known that the compound heterozygosity of disruptive variants in trans with a common hypomorphic risk haplotype (T-C-A) in the TBX6 gene contribute to 10% of congenital scoliosis (CS) cases. The deletion of chromosome 17q12 is a rare cytogenetic abnormality, which often leads to renal cysts and diabetes mellitus. However, the affected individuals often exhibit clinical heterogeneity and incomplete penetrance. METHODS: We here present a Chinese fetus who was shown to have CS by ultrasound examination at 17 weeks of gestation. Trio whole-exome sequencing (WES) was performed to investigate the underlying genetic defects of the fetus. In vitro functional experiments, including western-blotting and luciferase transactivation assay, were performed to determine the pathogenicity of the novel variant of TBX6. RESULTS: WES revealed the fetus harbored a compound heterozygous variant of c.338_340del (p.Ile113del) and the common hypomorphic risk haplotype of the TBX6 gene. In vitro functional study showed the p.Ile113del variant had no impact on TBX6 expression, but almost led to complete loss of its transcriptional activity. In addition, we identified a 1.85 Mb deletion on 17q12 region in the fetus and the mother. Though there is currently no clinical phenotype associated with this copy number variation in the fetus, it can explain multiple renal cysts in the pregnant woman. CONCLUSIONS: This study is the first to report a Chinese fetus with a single amino acid deletion variant and a T-C-A haplotype of TBX6. The clinical heterogeneity of 17q12 microdeletion poses significant challenges for prenatal genetic counseling. Our results once again suggest the complexity of prenatal genetic diagnosis.

[Clinical phenotype and genotype analysis of progressive familial intrahepatic cholestasis type 3 caused by novel ABCB4 gene mutation].

Objective: To investigate the pathogenic mechanism and clinical characteristics of the novel splicing variant of ATP-binding cassette subfamily B member 4 (ABCB4) and provide a basis for subsequent genetic diagnosis. Methods: The clinical data of a 5-year-old child with cholestatic liver disease admitted to the Beijing Children's Hospital of Capital Medical University was retrospectively analyzed. The pathogenic variations were detected by whole exome sequencing and verified by Sanger sequencing, and bioinformatics was used to predict the pathogenicity of the mutation sites. Possible pathogenic variations were verified in vitro by Minigene assay. The clinical outcome was followed after discharge from hospital. Results: The 5-year-old boy had developed cholestasis at the age of 11 months. His physical examination showed obvious enlargement of the liver and spleen. Cholestatic cirrhosis was diagnosed by liver function tests, abdominal ultrasonography, liver biopsy and pathology. The results of genetic analysis showed that the patient was a complex heterozygote of the ABCB4 gene, with a pathogenic mutation c.2860G>A and a novel mutation c.2065-8T>G, derived from the mother and father respectively. The conservative prediction of the c.2065-8T>G site showed that this region was highly conserved and may affect splicing. Minigene assay results confirmed that the c.2065-8T>G mutation resulted in a 7 bp retention of intron 16 in the mature mRNA. In the absence of nonsense-mediated mRNA decay, the amino acid frameshift forms a truncated protein, which is represented by p.Glu689ValfsTer19. The patient was diagnosed as progressive familial intrahepatic cholestasis type 3 (PFIC3) and treated with ursodeoxycholic acid (UDCA). His clinical symptoms improved during 18 months of follow-up. Conclusions: The c.2065-8T>G variant is confirmed to affect the splicing process and exhibits complex heterozygosity with c.2860G>A, which is identified as the cause of the disease. PFIC3 children with this variant showed cholestatic liver disease as the main manifestation with a slow progression and was sensitive to treatment with UDCA.

Clinical and genetic analysis of a case of O'Donnell-Luria-Rodan syndrome manifesting as growth retardation. / 以生长发育迟缓为表现的1例O'Donnell-Luria-Rodanç»¼åˆå¾ä¸´åºŠä¸Žé—ä¼ å­¦ç‰¹å¾åˆ†æž.

O'Donnell-Luria-Rodan (ODLURO) syndrome is an autosomal dominant genetic disorder caused by mutations in the KMT2E (lysine methyltransferase 2E) gene. The Third Xiangya Hospital of Central South University admitted a 12-year and 9-month-old male patient who presented with growth retardation, intellectual disability, and distinctive facial features. Peripheral blood was collected from the patient, and DNA was extracted for genetic testing. Chromosome karyotyping showed 46XY. Whole-exome sequencing and low-coverage massively parallel copy number variation sequencing (CNV-seq) revealed a 506 kb heterozygous deletion in the 7q22.3 region, which includes 6 genes, including KMT2E. The patient was diagnosed with ODLURO syndrome. Both the patient's parents and younger brother had normal clinical phenotypes and genetic test results, indicating that this deletion was a de novo mutation. The clinical and genetic characteristics of this case can help increase clinicians' awareness of ODLURO syndrome.

Peripheral T Cell Development and Immunophenotyping of Twins with Heterozygous FOXN1 Mutations.

The transcription factor FOXN1 plays an established role in thymic epithelial development to mediate selection of maturing thymocytes. Patients with heterozygous loss-of-function FOXN1 variants are associated with T cell lymphopenia at birth and low TCR excision circles that can ultimately recover. Although CD4+ T cell reconstitution in these patients is not completely understood, a lower proportion of naive T cells in adults has suggested a role for homeostatic proliferation. In this study, we present an immunophenotyping study of fraternal twins with low TCR excision circles at birth. Targeted primary immunodeficiency testing revealed a heterozygous variant of uncertain significance in FOXN1 (c.1205del, p.Pro402Leufs*148). We present the immune phenotypes of these two patients, as well as their father who carries the same FOXN1 variant, to demonstrate an evolving immune environment over time. While FOXN1 haploinsufficiency may contribute to thymic defects and T cell lymphopenia, we characterized the transcriptional activity and DNA binding of the heterozygous FOXN1 variant in 293T cells and found the FOXN1 variant to have different effects across several target genes. These data suggest multiple mechanisms for similar FOXN1 variants pathogenicity that may be mutation specific. Increased understanding of how these variants drive transcriptional regulation to impact immune cell populations will guide the potential need for therapeutics, risk for infection or autoimmunity over time, and help inform clinical decisions for other variants that might arise.

[Genetic analysis of a fetus with Rhizomelic skeletal dysplasia].

OBJECTIVE: To explore the clinical features and genetic basis for a fetus featuring Rhizomelic skeletal dysplasia. METHODS: A fetus diagnosed at the Reproductive and Genetic Center of Suzhou Municipal Hospital in November 2020 was selected as the study subject. Whole exome sequencing (WES) was carried out for the fetus and its parents. Candidate variants were verified by Sanger sequencing. Peripheral blood smears of both parents were also examined. RESULTS: The fetus was found to have a small chest and short limbs, which had suggested skeletal dysplasia. Genetic testing revealed that the fetus has harbored compound heterozygous variants of the LBR gene, including a paternally derived c.1687+1G>A and a maternally derived c.1757G>A (p.Arg586His). The blood smear of the father showed Pelger-Huet anomaly with hyposegmentation of neutrophil nuclei, while the neutrophils of the mother appeared to be normal. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP), the c.1757G>A (p.Arg586His) variant was classified as likely pathogenic (PM3_Strong+PM2_Supporting+PP3), and so was the c.1687+1G>A variant (PVS1-Moderate+PM3+PM2-Supporting+PP4). CONCLUSION: The compound heterozygous variants of the LBR gene probably underlay the pathogenesis of skeletal dysplasia in this fetus.

A compound heterozygote case of glutaric aciduria type II in a patient carrying a novel candidate variant in ETFDH gene: A case report and literature review on compound heterozygote cases.

BACKGROUND: Glutaric aciduria type II (GA2) is a rare genetic disorder inherited in an autosomal recessive manner. Double dosage mutations in GA2 corresponding genes, ETFDH, ETFA, and ETFB, lead to defects in the catabolism of fatty acids, and amino acids lead to broad-spectrum phenotypes, including muscle weakness, developmental delay, and seizures. product of these three genes have crucial role in transferring electrons to the electron transport chain (ETC), but are not directly involve in ETC complexes. METHODS: Here, by using exome sequencing, the cause of periodic cryptic gastrointestinal complications in a 19-year-old girl was resolved after years of diagnostic odyssey. Protein modeling for the novel variant served as another line of validation for it. RESULTS: Exome Sequencing (ES) identified two variants in ETFDH: ETFDH:c.926T>G and ETFDH:c.1141G>C. These variants are likely contributing to the crisis in this case. To the best of our knowledge at the time of writing this manuscript, variant ETFDH:c.926T>G is reported here for the first time. Clinical manifestations of the case and pathological analysis are in consistent with molecular findings. Protein modeling provided another line of evidence proving the pathogenicity of the novel variant. ETFDH:c.926T>G is reported here for the first time in relation to the causation GA2. CONCLUSION: Given the milder symptoms in this case, a review of GA2 cases caused by compound heterozygous mutations was conducted, highlighting the range of symptoms observed in these patients, from mild fatigue to more severe outcomes. The results underscore the importance of comprehensive genetic analysis in elucidating the spectrum of clinical presentations in GA2 and guiding personalized treatment strategies.

After an initial Hermansky-Pudlak syndrome clinical diagnosis, molecular testing reveals variants for oculocutaneous albinism type 1B: A case report.

BACKGROUND: Albinism is a heterogeneous condition in which patients present complete absence, reduction, or normal pigmentation in skin, hair and eyes in addition to ocular defects. One of the heterogeneous forms of albinism is observed in Hermansky-Pudlak syndrome (HPS) patients. HPS is characterized by albinism and hemorrhagic diathesis due to the absence of dense bodies in platelets. METHODS: In this report, we describe a case of a pair of Puerto Rican siblings with albinism that were clinically diagnosed with HPS during childhood. Since they did not harbor the founder changes in the HPS1 and HPS3 genes common in Puerto Ricans, as adults they wanted to know the type of albinism they had. We performed exome sequencing, validation by PCR, and cloning of PCR products followed by Sanger sequencing in the family members. RESULTS: We discovered no mutations that could explain an HPS diagnosis. Instead, we found the siblings were compound heterozygotes for 4 variants in the Tyrosinase gene: c.-301C>T, c.140G>A (rs61753180; p.G47D), c.575C>A (rs1042602; p.S192Y), and c.1205G>A (rs1126809; p.R402Q). Our results show that the correct diagnosis for the siblings is OCA1B. CONCLUSION: Our study shows the importance of molecular testing when diagnosing a rare genetic disorder, especially in populations were the disease prevalence is higher.

Exome Sequencing Identifies Carriers of the Autosomal Dominant Cancer Predisposition Disorders Beyond Current Practice Guideline Recommendations.

PURPOSE: The autosomal dominant cancer predisposition disorders hereditary breast and ovarian cancer (HBOC) and Lynch syndrome (LS) are genetic conditions for which early identification and intervention have a positive effect on the individual and public health. The goals of this study were to determine whether germline genetic screening using exome sequencing could be used to efficiently identify carriers of HBOC and LS. METHODS: Participants were recruited from three geographically and racially diverse sites in the United States (Rochester, MN; Phoenix, AZ; Jacksonville, FL). Participants underwent Exome+ sequencing (Helix Inc, San Mateo, CA) and return of results for specific genetic findings: HBOC (BRCA1 and BRCA1) and LS (MLH1, MSH2, MSH6, PMS2, and EPCAM). Chart review was performed to collect demographics and personal and family cancer history. RESULTS: To date, 44,306 participants have enrolled in Tapestry. Annotation and interpretation of all variants in genes for HBOC and LS resulted in the identification of 550 carriers (prevalence, 1.24%), which included 387 with HBOC (27.2% BRCA1, 42.8% BRCA2) and 163 with LS (12.3% MSH6, 8.8% PMS2, 4.5% MLH1, 3.8% MSH2, and 0.2% EPCAM). More than half of these participants (52.1%) were newly diagnosed carriers with HBOC and LS. In all, 39.2% of HBOC/LS carriers did not satisfy National Comprehensive Cancer Network (NCCN) criteria for genetic evaluation. NCCN criteria were less commonly met in underrepresented minority populations versus self-reported White race (51.5% v 37.5%, P = .028). CONCLUSION: Our results emphasize the need for wider utilization of germline genetic sequencing for enhanced screening and detection of individuals who have LS and HBOC cancer predisposition syndromes.

[Analysis of a family with 11ß-hydroxylase deficiency due to a mutation in the CYP11B1 gene].

This study reports a family of patients with 11ß-hydroxylase deficiency (11ß-OHD) caused by a novel mutation in the CYP11B1 gene, and analyzes its clinical and genetic characteristics. The clinical data of a patient with intractable hypertension at Air Force Medical Center on May 16, 2014 were retrospectively analyzed. The patient was clinically diagnosed with congenital adrenal cortical hyperplasia. The clinical data of the patient were further collected and the peripheral blood samples of the patient, his parents and his sister were collected for CYP11B1(NM_000497) gene sequencing, suggesting that the patient had compound heterozygous mutations in exon 1:c.199delG, p.Glu67Lysfs*9 and exon 5:c.905_907 delATGinsTT, p.Asp302Valfs*23, both of which were pathogenic variants. The patient's father and sister carried heterozygous mutations in exon 1:c.199delG, p.Glu67Lysfs*9, and the mother carried heterozygous mutations in exon 5:c.905_907delATGinsTT, p.Asp302Valfs*23. This study is the first to report a new compound heterozygous mutation in exon 1:c.199delG and exon 5 c.905_907 delATGinsTT of CYP11B1 gene, enriching the database of 11ß-OHD mutations and providing information to further understand the genetic mechanism of the disease.

Compound Heterozygous Mutations of SACS in a Korean Cohort Study of Charcot-Marie-Tooth Disease Concurrent Cerebellar Ataxia and Spasticity.

Mutations in the SACS gene are associated with autosomal recessive spastic ataxia of Charlevoix-Saguenay disease (ARSACS) or complex clinical phenotypes of Charcot-Marie-Tooth disease (CMT). This study aimed to identify SACS mutations in a Korean CMT cohort with cerebellar ataxia and spasticity by whole exome sequencing (WES). As a result, eight pathogenic SACS mutations in four families were identified as the underlying causes of these complex phenotypes. The prevalence of CMT families with SACS mutations was determined to be 0.3%. All the patients showed sensory, motor, and gait disturbances with increased deep tendon reflexes. Lower limb magnetic resonance imaging (MRI) was performed in four patients and all had fatty replacements. Of note, they all had similar fatty infiltrations between the proximal and distal lower limb muscles, different from the neuromuscular imaging feature in most CMT patients without SACS mutations who had distal dominant fatty involvement. Therefore, these findings were considered a characteristic feature in CMT patients with SACS mutations. Although further studies with more cases are needed, our results highlight lower extremity MRI findings in CMT patients with SACS mutations and broaden the clinical spectrum. We suggest screening for SACS in recessive CMT patients with complex phenotypes of ataxia and spasticity.

Generation of iPSC line NCHi015-A from a patient with truncus arteriosus carrying heterozygous variants in KMT2D and NOTCH1.

Truncus arteriosus (TA) is a congenital heart defect where one main blood vessel emerges from the heart, instead of individual aorta and pulmonary artreries. Peripheral mononuclear cells (PBMCs) of a male infant with TA were reporogrammed using Sendai virus. The resultant iPSC line (NCHi015-A) displayed normal colony formation, expressed pluripotency markers, and differentiated into cells from three germ layers. NCHi015-A was matched to the patient's genetic profile, had normal karyotype, retained genetic variants in KMT2D and NOTCH1, and tested negative for reprogramming transgene. This iPSC line can be used for studying congenital heart defects associated with genetic variants in KMT2D and NOTCH1.

Fluid Biomarkers in Individuals at Risk for Genetic Prion Disease up to Disease Conversion.

OBJECTIVES: To longitudinally characterize disease-relevant CSF and plasma biomarkers in individuals at risk for genetic prion disease up to disease conversion. METHODS: This single-center longitudinal cohort study has followed known carriers of PRNP pathogenic variants at risk for prion disease, individuals with a close relative who died of genetic prion disease but who have not undergone predictive genetic testing, and controls. All participants were asymptomatic at first visit and returned roughly annually. We determined PRNP genotypes, measured NfL and GFAP in plasma, and RT-QuIC, total PrP, NfL, T-tau, and beta-synuclein in CSF. RESULTS: Among 41 carriers and 21 controls enrolled, 28 (68%) and 15 (71%) were female, and mean ages were 47.5 and 46.1. At baseline, all individuals were asymptomatic. We observed RT-QuIC seeding activity in the CSF of 3 asymptomatic E200K carriers who subsequently converted to symptomatic and died of prion disease. 1 P102L carrier remained RT-QuIC negative through symptom conversion. No other individuals developed symptoms. The prodromal window from detection of RT-QuIC positivity to disease onset was 1 year long in an E200K individual homozygous (V/V) at PRNP codon 129 and 2.5 and 3.1 years in 2 codon 129 heterozygotes (M/V). Changes in neurodegenerative and neuroinflammatory markers were variably observed prior to onset, with increases observed for plasma NfL in 4/4 converters, and plasma GFAP, CSF NfL, CSF T-tau, and CSF beta-synuclein each in 2/4 converters, although values relative to age and fold changes relative to individual baseline were not remarkable for any of these markers. CSF PrP was longitudinally stable with mean coefficient of variation 9.0% across all individuals over up to 6 years, including data from converting individuals at RT-QuIC-positive timepoints. DISCUSSION: CSF prion seeding activity may represent the earliest detectable prodromal sign in E200K carriers. Neuronal damage and neuroinflammation markers show limited sensitivity in the prodromal phase. CSF PrP levels remain stable even in the presence of RT-QuIC seeding activity. CLINICAL TRIALS REGISTRATION: ClinicalTrials.gov NCT05124392 posted 2017-12-01, updated 2023-01-27.

A Molecular Characterization of the Allelic Expression of the BRCA1 Founder Δ9-12 Pathogenic Variant and Its Potential Clinical Relevance in Hereditary Cancer.

Hereditary breast and ovarian cancer (HBOC) syndrome is a genetic condition that increases the risk of breast cancer by 80% and that of ovarian cancer by 40%. The most common pathogenic variants (PVs) causing HBOC occur in the BRCA1 gene, with more than 3850 reported mutations in the gene sequence. The prevalence of specific PVs in BRCA1 has increased across populations due to the effect of founder mutations. Therefore, when a founder mutation is identified, it becomes key to improving cancer risk characterization and effective screening protocols. The only founder mutation described in the Mexican population is the deletion of exons 9 to 12 of BRCA1 (BRCA1Δ9-12), and its description focuses on the gene sequence, but no transcription profiles have been generated for individuals who carry this gene. In this study, we describe the transcription profiles of cancer patients and healthy individuals who were heterozygous for PV BRCA1Δ9-12 by analyzing the differential expression of both alleles compared with the homozygous BRCA1 control group using RT-qPCR, and we describe the isoforms produced by the BRCA1 wild-type and BRCA1Δ9-12 alleles using nanopore long-sequencing. Using the Kruskal-Wallis test, our results showed a similar transcript expression of the wild-type allele between the healthy heterozygous group and the homozygous BRCA1 control group. An association between the recurrence and increased expression of both alleles in HBOC patients was also observed. An analysis of the sequences indicated four wild-type isoforms with diagnostic potential for discerning individuals who carry the PV BRCA1Δ9-12 and identifying which of them has developed cancer.

[Molecular Diagnosis and Pedigree Analysis of Rare Mutations in Non-coding Region of HBA2 Gene].

OBJECTIVE: To perform molecular diagnosis and pedigree analysis for one case with α-thalassemia who does not conform to the genetic laws, and explore the effects of a newly discovered rare mutation (HBA2:c.*12G>A) on clinical phenotypes. METHODS: Blood samples of the proband and her family members were collected for blood routine analysis, and the hemoglobin components were analyzed by capillary electrophoresis. The common α- and ß-globin gene loci in Chinese population were detected by conventional techniques (Gap-PCR, RDB-PCR). The α-globin gene sequences (HBA1, HBA2) were analyzed by Sanger sequencing. RESULTS: By analyzing the test results of proband and her family members, the genotype of the proband was -α3.7/HBA2:c.*12G>A, her father was HBA2:c.*12G>A heterozygous mutation carrier. CONCLUSION: This study identifies a rare α-globin gene mutation (HBA2:c.*12G>A) that has not been reported before. It is found that heterozygous mutation carriers present with static α-thalassemia.