Digenic Inheritance and Gene-Environment Interaction in a Patient With Hypertriglyceridemia and Acute Pancreatitis.
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ABSTRACT:
SUBMITTER: Yang Q
PROVIDER: S-EPMC8143378 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BACKGROUND:ENAM mutations cause autosomal dominant or recessive amelogenesis imperfecta (AI) and show a dose effect: enamel malformations are more severe or only penetrant when both ENAM alleles are defective. METHODS:Whole exome sequences of recruited AI probands were initially screened for mutations in known AI candidate genes. Sanger sequencing was used to confirm sequence variations and their segregation with the disease phenotype. The co-occurrence of ENAM and LAMA3 mutations in one family raised the possibility of digenic inheritance. Enamel formed in Enam+/+ Ambn+/+ , Enam+/- , Ambn+/- , and Enam+/- Ambn+/- mice was characterized by dissection and backscattered scanning electron microscopy (bSEM). RESULTS:ENAM mutations segregating with AI in five families were identified. Two novel ENAM frameshift mutations were identified. A single-nucleotide duplication (c.395dupA/p.Pro133Alafs*13) replaced amino acids 133-1142 with a 12 amino acid (ATTKAAFEAAIT*) sequence, and a single-nucleotide deletion (c.2763delT/p.Asp921Glufs*32) replaced amino acids 921-1142 with 31 amino acids (ESSPQQASYQAKETAQRRGKAKTLLEMMCPR*). Three families were heterozygous for a previously reported single-nucleotide ENAM deletion (c.588+1delG/p.Asn197Ilefs*81). One of these families also harbored a heterozygous LAMA3 mutation (c.1559G>A/p.Cys520Tyr) that cosegregated with both the AI phenotype and the ENAM mutation. In mice, Ambn+/- maxillary incisors were normal. Ambn+/- molars were also normal, except for minor surface roughness. Ambn+/- mandibular incisors were sometimes chalky and showed minor chipping. Enam+/- incisor enamel was thinner than normal with ectopic mineral deposited laterally. Enam+/- molars were sometimes chalky and rough surfaced. Enam+/- Ambn+/- enamel was thin and rough, in part due to ectopic mineralization, but also underwent accelerated attrition. CONCLUSION:Novel ENAM mutations causing AI were identified, raising to 22 the number of ENAM variations known to cause AI. The severity of the enamel phenotype in Enam+/- Ambn+/- double heterozygous mice is caused by composite digenic effects. Digenic inheritance should be explored as a cause of AI in humans.
| S-EPMC6785452 | biostudies-literature
Project description:Digenic inheritance (DI) is the simplest form of inheritance for genetically complex diseases. By contrast with the thousands of reports that mutations in single genes cause human diseases, there are only dozens of human disease phenotypes with evidence for DI in some pedigrees. The advent of high-throughput sequencing (HTS) has made it simpler to identify monogenic disease causes and could similarly simplify proving DI because one can simultaneously find mutations in two genes in the same sample. However, through 2012, I could find only one example of human DI in which HTS was used; in that example, HTS found only the second of the two genes. To explore the gap between expectation and reality, I tried to collect all examples of human DI with a narrow definition and characterise them according to the types of evidence collected, and whether there has been replication. Two strong trends are that knowledge of candidate genes and knowledge of protein-protein interactions (PPIs) have been helpful in most published examples of human DI. By contrast, the positional method of genetic linkage analysis, has been mostly unsuccessful in identifying genes underlying human DI. Based on the empirical data, I suggest that combining HTS with growing networks of established PPIs may expedite future discoveries of human DI and strengthen the evidence for them.
| S-EPMC3778050 | biostudies-literature
Project description:ObjectiveTo assess the response of serum triglycerides (TG) to continuous insulin infusion (CII) in adults with hypertriglyceridemia-associated acute pancreatitis (HTGP).MethodsRetrospective analysis of TG response to standardized CII therapy in 77 adults admitted to intensive care with TG >1000 mg/dL and HTGP.ResultsParticipants had initial TG 3869.0 [2713.5, 5443.5] mg/dL and were 39.3 ± 9.7 years old, 66.2% males, 58.4% Hispanic, BMI 30.2 [27.0, 34.8] kg/m2, 74.0% with diabetes mellitus (DM) and 50.6% with excess alcohol use. TG-goal, defined as ≤1,000 ± 100 mg/dL, was achieved in 95%. Among the 73 TG-goal achievers (responders), 53.4% reached TG-goal in <36 hours after CII initiation (rapid responders). When compared to slow responders taking≥36 hours, rapid responders had lower initial TG (2862.0 [1965.0, 4519.0] vs 4814.5 [3368.8, 6900.0] mg/dL), BMI (29.4 [25.9, 32.8] vs 31.9 [28.2, 38.3] kg/m2), DM prevalence (56.4 vs 94.1%), and reached TG-50% (half of respective initial TG) faster (12.0 [6.0, 17.0] vs 18.5 [13.0, 32.8] hours). Those with DM (n = 57) vs non-DM (n = 20) were obese (31.4 [28.0, 35.6] vs 27.8 [23.6, 30.3] kg/m2), took longer to reach TG-final (41.0 [25.0, 60.5] vs 14.5 [12.5, 25.5] hours) and used more daily insulin (1.7 [1.3, 2.1] vs 1.1 [0.5, 1.9] U/kg/day). Among those with DM, the rapid responders had higher daily use of insulin vs slow responders 1.9 [1.4, 2.3] vs 1.6 [1.1, 1.8] U/kg/day. All results significant. In multivariable analysis, predictors of faster TG response were absence of DM, lower BMI and initial TG.ConclusionCII was effective in reaching TG-goal in 95% of patients with HTGP. Half achieved TG-goal within 36 hours. Presence of DM, higher BMI and initial TG slowed the time to reach TG-goal. These baseline parameters and rate of decline to TG-50% may be real-time indicators to initiate and adjust the CII for quicker response.
| S-EPMC8631651 | biostudies-literature
Project description:Background and objectives: Dilated cardiomyopathy (DCM) is a rare cardiac disease characterised by left ventricular enlargement, reduced left ventricular contractility, and impaired systolic function. Childhood DCM is clinically and genetically heterogenous and associated with mutations in over 100 genes. The aim of this study was to identify novel variations associated with infantile DCM. Materials and Methods: Targeted next generation sequencing (NGS) of 181 cardiomyopathy-related genes was performed in three unrelated consanguineous families from Saudi Arabia. Variants were confirmed and their frequency established in 50 known DCM cases and 80 clinically annotated healthy controls. Results: The three index cases presented between 7 and 10 months of age with severe DCM. In Family A, there was digenic inheritance of two heterozygous variants: a novel variant in LAMA4 (c.3925G > A, p.Asp1309Asn) and a known DCM mutation in MYH7 (c.2770G > A; p.Glu924Lys). The LAMA4 p.Asp1309Asn variant was predicted to be likely pathogenic according to international guidelines. The other two families had no identifiable potentially deleterious variants. Conclusions: Inheritance of two genetic variants may have a synergistic or dose effect to cause severe DCM. We report of a novel p.Asp1309Asn variation associated with DCM. Targeted NGS is useful in the molecular diagnosis of DCM and to guide whole-family management and counselling.
| S-EPMC6359299 | biostudies-literature
Project description:"Early-onset glaucoma" refers to genetically heterogeneous conditions for which glaucoma manifests at age 5-40 years and for which only a small subset is molecularly characterized. We studied the role of MYOC, CYP1B1, and PITX2 in a population (n=60) affected with juvenile or early-onset glaucoma from the greater Toronto area. By a combination of single-strand conformation polymorphism and direct cycle sequencing, MYOC mutations were detected in 8 (13.3%) of the 60 individuals, CYP1B1 mutations were detected in 3 (5%) of the 60 individuals, and no PITX2 mutations were detected. The range of phenotypic expression associated with MYOC and CYP1B1 mutations was greater than expected. MYOC mutations included cases of juvenile glaucoma with or without pigmentary glaucoma and mixed-mechanism glaucoma. CYP1B1 mutations involved cases of juvenile open-angle glaucoma, as well as cases of congenital glaucoma. The study of a family with autosomal dominant glaucoma showed the segregation of both MYOC and CYP1B1 mutations with disease; however, in this family, the mean age at onset of carriers of the MYOC mutation alone was 51 years (range 48-64 years), whereas carriers of both the MYOC and CYP1B1 mutations had an average age at onset of 27 years (range 23-38 years) (P=.001). This work emphasizes the genetic heterogeneity of juvenile glaucoma and suggests, for the first time, that (1) congenital glaucoma and juvenile glaucoma are allelic variants and (2) the spectrum of expression of MYOC and CYP1B1 mutations is greater than expected. We also propose that CYP1B1 may act as a modifier of MYOC expression and that these two genes may interact through a common pathway.
| S-EPMC384919 | biostudies-literature
Project description:IntroductionAcute pancreatitis (AP) is a serious inflammatory condition of the pancreas. Hypertriglyceridemia (HTG) is considered an uncommon cause of AP. The current study aims to present a unique case of recurrent seasonal severe HTG-induced AP (HTG-AP); treated with insulin and heparin.Case reportA 36-year-old male presented with recurrent attacks of severe upper abdominal pain that was radiating to the back and associated with repeated vomiting. The condition has being occurring every autumn-winter for the last three years. He had thalassemia minor and had a history of HTG-AP. His TG levels were relatively normal from February to August; however, from September to February, his TG levels highly elevated which has resulted in HTG-AP every year for the past three years. The condition was confirmed via a contrast-enhanced computerized tomography scan of the abdomen. To prevent the next HTG-AP, his TG level was monitored monthly. When TG levels spiked again, the patient was put on an insulin infusion with heparin, glucose, and potassium to rapidly reduce TG level. After two days, serum TG was dramatically reduced (<500 mg/dL).DiscussionDespite multiple theories being proposed, the pathogenesis of HTG-AP is yet to be understood. Usually, HTG-AP is a single episodic, and recurrent HTG-AP is considered uncommon finding. Previous reports are contradictory regarding TG level and seasonal variation. There is currently no standard management approach to treat HTG-AP cases.ConclusionHTG-AP rarely reoccurs on an annual basis, and seasonal variation seems to play a major role in its onset. The condition can be managed with insulin, heparin, and glucose infusions.
| S-EPMC8977940 | biostudies-literature
Project description:Cystinuria is an aminoaciduria caused by mutations in the genes that encode the two subunits of the amino acid transport system b0,+, responsible for the renal reabsorption of cystine and dibasic amino acids. The clinical symptoms of cystinuria relate to nephrolithiasis, due to the precipitation of cystine in urine. Mutations in SLC3A1, which codes for the heavy subunit rBAT, cause cystinuria type A, whereas mutations in SLC7A9, which encodes the light subunit b0,+AT, cause cystinuria type B. By crossing Slc3a1-/- with Slc7a9-/- mice we generated a type AB cystinuria mouse model to test digenic inheritance of cystinuria. The 9 genotypes obtained have been analyzed at early (2- and 5-months) and late stage (8-months) of the disease. Monitoring the lithiasic phenotype by X-ray, urine amino acid content analysis and protein expression studies have shown that double heterozygous mice (Slc7a9+/-Slc3a1+/-) present lower expression of system b0,+ and higher hyperexcretion of cystine than single heterozygotes (Slc7a9+/-Slc3a1+/+ and Slc7a9+/+Slc3a1+/-) and give rise to lithiasis in 4% of the mice, demonstrating that cystinuria has a digenic inheritance in this mouse model. Moreover in this study it has been demonstrated a genotype/phenotype correlation in type AB cystinuria mouse model providing new insights for further molecular and genetic studies of cystinuria patients.
| S-EPMC4567282 | biostudies-literature
Project description:BackgroundArrhythmogenic cardiomyopathy (ACM) is an inherited genetic disorder, characterized by the substitution of heart muscle with fibro-fatty tissue and severe ventricular arrhythmias, often leading to heart failure and sudden cardiac death. ACM is considered a monogenic disorder, but the low penetrance of mutations identified in patients suggests the involvement of additional genetic or environmental factors.MethodsWe used whole exome sequencing to investigate digenic inheritance in two ACM families where previous diagnostic tests have revealed a PKP2 mutation in all affected and some healthy individuals. In family members with PKP2 mutations we determined all genes that harbor variants in affected but not in healthy carriers or vice versa. We computationally prioritized the most likely candidates, focusing on known ACM genes and genes related to PKP2 through protein interactions, functional relationships, or shared biological processes.ResultsWe identified four candidate genes in family 1, namely DAG1, DAB2IP, CTBP2 and TCF25, and eleven candidate genes in family 2. The most promising gene in the second family is TTN, a gene previously associated with ACM, in which the affected individual harbors two rare deleterious-predicted missense variants, one of which is located in the protein's only serine kinase domain.ConclusionsIn this study we report genes that might act as digenic players in ACM pathogenesis, on the basis of co-segregation with PKP2 mutations. Validation in larger cohorts is still required to prove the utility of this model.
| S-EPMC5723071 | biostudies-literature
Project description:BackgroundVariants in the lipoprotein lipase (LPL), apolipoprotein C-II (APOC2), apolipoprotein A-V (APOA5), GPIHBP1 and LMF1 genes may cause severe hypertriglyceridemia (HTG), which is now the second-leading aetiology of acute pancreatitis in China.MethodsThe patient and his family were assessed for gene variants by Sanger sequencing of exons and exon-intron junctions of the LPL, GPIHBP1, APOA5, APOC2, and LMF1 genes. Post-heparin blood was collected for LPL mass and activity detection.ResultsThe patient had suffered from long-term severe hypertriglyceridemia and recurrent abdominal pain for over 30 years, since age 26, and 3 bouts of acute pancreatitis. Two heterozygous LPL single-nucleotide polymorphisms (SNPs) were compound but dislinked: a single-nucleotide substitution (c.42G > A) resulting in the substitution of tryptophan with a stop codon (p.W14X) in one allele, and a single-nucleotide substitution (c.835C > G) resulting in a leucine-to-valine substitution (p.L279 V) in another allele. Only one SNP, p.L279 V, was detected in his son. Post-heparin LPL activity and mass were also lower in the patient.ConclusionTwo heterozygous LPL SNPs, W14X and L279 V, were newly found to be compound but dislinked, which may cause long-term severe hypertriglyceridemia and recurrent acute pancreatitis.
| S-EPMC6009947 | biostudies-literature
Project description:BackgroundMostly published as case reports or series, the role of apheresis in hypertriglyceridemia (HTG)-related acute pancreatitis (AP) remains unclear. We performed a systematic review of available literature on this topic with specific focus on disease severity.MethodsA search of electronic databases (PubMed, EMBASE, Cochrane) and gray literature yielded 5020 articles of which 74 met criteria for inclusion (301 unique patients). Relevant data were abstracted from full manuscripts and analyzed.ResultsMost patients were young (mean age 37.9 ± 10.4 years) and male (71.5%). About two-thirds (69.7%) received apheresis within 48 h and most required only 1 or 2 sessions (84.4%). Apheresis resulted in an average reduction of serum TG by 85.4% (p < 0.001). There was high variability in reporting the presence of and criteria to define severe AP (reported 221/301, 73.4%; present 85/221, 38.5%) or organ failure (reported 104/301, 34.6%; present 52/104, 50.0%). Improvement was reported in the majority of patients (reported 144/301, 47.8%, present 136/144, 94.4%) mainly by clinical symptoms or laboratory tests. Overall mortality was 7.1% (21/294) which increased to 11.8% (10/85) with severe AP and 19.2% (10/52) with organ failure.ConclusionsApheresis effectively reduces serum TG levels. However, due to uncontrolled data, reporting bias and lack of a comparison group, definitive conclusions on the efficacy of apheresis in reducing AP severity cannot be made. We propose which patients may be best suitable for apheresis, type of studies needed and outcome measures to be studied in order to provide empiric data on the role of apheresis in HTG-related AP.
| S-EPMC6609092 | biostudies-literature