Application of Clinical Genetics最新文献

Introduction: Inborn errors of immunity (IEI) are disorders that present a health issue, especially in developing countries where there is a high rate of consanguineous marriages and an increasing rate of diagnosis. One of these disorders is Bare Lymphocyte Syndrome II (BLS II) which is a rare and genetically complex disease that has high morbidity and mortality. The exact genotypic and phenotypic characteristics are still poorly characterized especially in developing countries.

Case presentation: Here, we report the first case of BLS II in a seven-month-old Sudanese female with recurrent chest infections, dermatitis, persistent diarrhea, and failure to thrive. The patient's all four sisters and three paternal uncles died in early infancy. Laboratory investigations revealed low CD3+, CD4+, and CD8+ lymphocytes, along with normal CD19+ and CD16+ lymphocytes, and low serum IgM and IgA levels. Genetic analysis revealed two CIITA variants; c.2296C >G p. (Pro766Ala) and c.439+1G >A.

Conclusion: Further bioinformatics, immunological and clinical workups supported a pathogenic effect of both mutations affecting the function of CIITA protein, and suggesting a compound heterozygote mutation. The patient was started on prophylactic antibiotics and regular intravenous immunoglobulin replacement therapy. The prognosis of this disease is poor in most of the cases, with only a few reported cases surviving until adulthood.

[This corrects the article DOI: 10.2147/TACG.S363685.].

Introduction: There are more than 6000 genetic syndromes, therefore the recognition of facial patterns may present a challenge for clinicians. The 22q11.2 deletion syndrome (22q11.2 DS) and Williams syndrome (WS) are two different genetic syndromes but share some common phenotypic traits and subtle facial dysmorphisms. Therefore, any tool that would help clinicians recognize genetic syndromes would likely result in a more accurate diagnosis.

Methods: The syndrome identification accuracy was compared between 2 different facial analysis algorithms (DeepGestalt and GestaltMatcher) of the Face2Gene (F2G) tool and a group of 9 clinicians with different levels of expertise before and after using F2G for a cohort of 64 Thai participants' frontal facial photos divided into 3 groups of 22q11.2 DS, WS and unaffected controls.

Results: The higher accuracy from the DeepGestalt algorithm than from clinicians was demonstrated, especially when comparing between the two syndromes. The accuracy was highest when clinicians use the tool combined with their own decision-making process. The tool's second algorithm, GestaltMatcher revealed clear separation among these three groups of photos.

Discussion: The result of F2G outperforming clinicians was not surprising. However, the highest increase in accuracy was with nondysmorphology clinicians using F2G.

Conclusion: Face2Gene would be a useful tool to help clinicians in facial recognition of genetic syndromes, before ordering specific tests to confirm the definite diagnosis.

Introduction: CYP2C19 plays a major role in the metabolism of various drugs. The most common genetic variants were the CYP2C19*2 and *3 alleles (rs4244285 and rs4986893, non-functional variants). In previous studies, we found that genetic polymorphisms in CYP2C19 variants influenced the active metabolites of clopidogrel and caused major adverse cardiovascular and cerebrovascular effects. However, the distribution of CYP2C19 varies among ethnic groups and according to adverse drug reactions. This study aimed to investigate the frequency of CYP2C19 genetic polymorphisms in the Thai population and analyze the differences in the frequency of CYP2C19 genetic polymorphisms between Thai and other populations.

Methods: This study enrolled 211 unrelated healthy Thai individuals in total. We performed a real-time polymerase chain reaction to genotype CYP2C19*2 (681G > A) and CYP2C19*3 (636G > A).

Results: In the Thai population, the CYP2C19*1 allele was the most prevalent at 70.14%, while the CYP2C19*2 and *3 alleles were found at frequencies of 25.36% and 4.50%, respectively. Conversely, the CYP2C19*3 allele was not detected in Caucasian, Hispanic, African, Italian, Macedonian, Tanzanian, or North Indian populations. The phenotypic profile of this gene revealed that the frequency of intermediate metabolizers (IMs) is nearly equal to that of extensive metabolizers (EMs), at 42.65% and 48.82% respectively, with genotypes *1/*2 (36.02%) and *1/*3 (6.63%). Likewise, poor metabolizers (PMs) with genotypes *2/*2 (6.16%), *2/*3 (2.37%), and *3/*3 (<1%) are more prevalent in our population as well.

Conclusion: The distribution of CYP2C19 genotype and phenotype influenced by non-functional alleles has potential as a pharmacogenomics biomarker for precision medicine and is dependent on an ethnic-specific genetic variation database.

Background: Charcot-Marie-Tooth disease (CMT) is a heterogeneous group of disorders involving peripheral nervous system. Charcot-Marie-Tooth disease 4B1 (CMT4B1) is a rare subtype of CMT. CMT4B1 is an axonal demyelinating polyneuropathy with an autosomal recessive mode of inheritance. Patients with CMT4B1 usually manifested with dysfunction of the motor and sensory systems which leads to gradual and progressive muscular weakness and atrophy, starting from the peroneal muscles and finally affecting the distal muscles. Germline mutations in MTMR2 gene causes CMT4B1.

Material and methods: In this study, we investigated a 4-year-old Chinese boy with gradual and progressive weakness and atrophy of both proximal and distal muscles. The proband's parents did not show any abnormalities. Whole-exome sequencing and Sanger sequencing were performed.

Results: Whole-exome sequencing identified a novel homozygous nonsense mutation (c.118A>T; p.Lys40*) in exon 2 of MTMR2 gene in the proband. This novel mutation leads to the formation of a truncated MTMR2 protein of 39 amino acids instead of the wild- type MTMR2 protein of 643 amino acids. This mutation is predicted to cause the complete loss of the PH-GRAM domain, phosphatase domain, coiled-coil domain, and PDZ-binding motif of the MTMR2 protein. Sanger sequencing revealed that the proband's parents carried the mutation in a heterozygous state. This mutation was absent in 100 healthy control individuals.

Conclusion: This study reports the first mutation in MTMR2 associated with CMT4B1 in a Chinese population. Our study also showed the importance of whole-exome sequencing in identifying candidate genes and disease-causing variants in patients with CMT4B1.

Background: The potential causes of miscarriage are very complex, including genetic, immune, infectious, and endocrine factors. 50%-60% of miscarriages are caused by chromosomal abnormalities. Chromosomal microarray analysis (CMA) is a key tool in this context, capable of detecting not only copy number variations (CNV) but also loss of heterozygosity (LOH). CMA has been used as a tool to investigate the genetic reasons for miscarriage.

Methods: In our study, chromosomal microarray analysis (CMA) conducted 1220 miscarriage villous tissues. The results from this technology were used to identify the genetic reasons for miscarriage and evaluated strategies for subsequent pre-pregnancy planning.

Results: Here, the abnormality rate of miscarriage was 56.07%(684/1220). The aneuploidy rate accounted for 81.14%(555/684), and was significantly higher in group >35-year-old age. The second most common genetic reason for miscarriage was polyploidy, accounting for 10.09%(69/684). Additionally, we discovered loss of heterozygosity (LOH) in a small percentage of cases, accounting for 2.20%(15/684) reason for miscarriage genetic reasons, due to the advantage of CMA can detect isodisomy (a kind of uniparental disomy). 45 cases (6.58%) with copy number variants, which due to the CMA can detect copy number variations.

Conclusion: Our study indicated that miscarriage villous tissues should be performed genetic analysis, seek help from professional genetic counseling.

Optical Genome Mapping (OGM) technology has garnered growing interest for the identification of chromosomal structural variations (SVs), particularly complex ones that are implicated in genetic diseases in humans. In this study, we performed genetic diagnostics on a neonatal patient who presented with feeding difficulties, hypotonia, and an atrial septal defect. We utilized a combination of trio-whole exome sequencing and OGM for our analysis. The results revealed an unbalanced translocation between maternal chromosomes 4 and 6 in the proband, ogm[GRch38]t(4:6)(q35.2;q25.3), resulting in a 2.8 Mb deletion at the 4q35 terminal and a 10.2 Mb duplication at the 6q25 terminal. In summary, this study highlights how OGM, in conjunction with other genetic approaches, can unveil the genetic etiology of complex clinical syndromes. Neonatal patients often exhibit low specific phenotypes, underlining the significance of SV detection.

Background: Androgen resistance syndrome or androgen insensitivity syndrome (AIS - Androgen Insensitivity Syndrome, OMIM 300068) is an X-linked recessive genetic syndrome causing disorders of sexual development in males. This disease is caused by mutations in the AR gene located on the X chromosome, which encodes the protein that structures the androgen receptor, with the role of receiving androgens. Mutation of the AR gene causes complete or partial loss of androgen receptor function, thereby androgen not being obtained and exerting its effect on target organs, resulting in abnormalities of the male reproductive system due to this organ system, differentiating towards feminization under the influence of estrogen. Disease prevention can be achieved by using pre-implantation genetic diagnosis, which enables couples carrying the mutation to have healthy offspring.

Aim: To carry out preimplantation genetic diagnosis of androgen resistance syndrome.

Methods: Sanger sequencing was used to detect the mutation in the blood samples of the couple, their son, and 01 embryo that were biopsied on the fifth day based on the findings of next-generation sequencing (NGS) of the affected son. We combined Sanger sequencing and linkage analysis using short tandem repeats (STR) to provide diagnostic results.

Results: We performed preimplantation genetic diagnosis for AIS on an embryo from a couple who had previously had an affected son. Consequently, one healthy embryo was diagnosed without the variant NM_000044: c.796del (p.Asp266IlefsTer30).

Conclusion: We report on a novel variant (NM_000044: c.796del (p.Asp266IlefsTer30)) in the AR gene discovered in Vietnam. The developed protocol was helpful for the preimplantation genetic diagnosis process to help families with the monogenic disease of AIS but wish to have healthy children.

Mutations in the lecithin-cholesterol acyltransferase (LCAT) gene, which catalyzes the esterification of cholesterol, result in two types of autosomal recessive disorders: Familial LCAT deficiency (FLD) and Fish Eye Disease (FED). While both phenotypes are characterized by corneal opacities and different forms of dyslipidemia, such as low levels of high-density lipoprotein-cholesterol (HDL-C), FLD exhibits more severe clinical manifestations like splenomegaly, anemia, and renal failure. We describe the first clinically and genetically confirmed case of FLD in Colombia which corresponds to a 46-year-old woman with corneal opacity, hypothyroidism, and dyslipidemia, who does not have any manifestations of renal failure, with two pathogenic heterozygous missense variants in the LCAT gene: LCAT (NM_000229.2):c.803G>A (p.Arg268His) and LCAT (NM_000229.2):c.368G>C (p.Arg123Pro). In silico analysis of the mutations predicted the physicochemical properties of the mutated protein, causing instability and potentially decreased LCAT function. These compound mutations highlight the clinical heterogeneity of the phenotypes associated with LCAT gene mutations.

Background: Congenital sucrase isomaltase deficiency (CSID) is in general a very rare disease. However, 2-3% of the Greenlandic population are homozygous (HO) carriers of an Arctic-specific loss-of-function (LoF) variant in the sucrase-isomaltase (SI) encoding gene, causing CSID. The condition is characterized by gastrointestinal symptoms such as stomachache, diarrhea, and weight loss when consuming sucrose, the most common dietary sugar. However, the awareness of the condition in the population and the healthcare system seems to be limited, potentially leading to a higher healthcare burden. Hence, we aimed to investigate whether HO-carriers visit the healthcare system more with gastrointestinal symptoms compared to the control groups by using registry data.

Methods: We performed a case-control study identifying cases and controls using genotype information from the 1999-2001 and 2005-2010 Greenlandic health population cohorts. The cases were defined as HO LoF SI-carriers and controls were defined as non-carriers and were matched (1:1) on sex, age, place of residence, and European genetic admixture. We used electronic medical records to assess the number of electronic medical record contacts (EMRc) related to gastrointestinal symptoms and the number of gastrointestinal-related diagnostic procedures.

Results: A total of 80 HO-carriers and 80 non-carriers were included. The HO-carriers had 19% more EMRc related to gastrointestinal symptoms (IRR, 1.19, 95% CI [1.02;1.40], p=0.02) and had a 41% higher incidence of gastrointestinal related diagnostic procedures compared to controls (IRR, 1.41, 95% CI [1.05-1.92], p=0.02). Only one HO-carrier was aware of the condition according to the electronic medical records.

Conclusion: HO-carriers of the LoF SI-variant had both significantly more gastrointestinal-related EMRc and significantly more diagnostic procedures conducted due to gastrointestinal symptoms. Only one HO-carrier was aware of the condition. Given the high prevalence of HO-carriers in the Greenlandic population, we anticipate that diagnosing more patients with CSID and providing dietary advice could potentially reduce symptom burden and healthcare visits among HO-carriers.