BMC Medical Genetics

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ISSN / EISSN : 1471-2350 / 1471-2350
Total articles ≅ 2,290
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Jung Yeon Seo, Joong-Gon Shin, Byeong Ju Youn, Suhg Namgoong, Hyun Sub Cheong, Lyoung Hyo Kim, Ji On Kim, ,
Published: 17 December 2020
BMC Medical Genetics, Volume 21, pp 1-9; doi:10.1186/s12881-020-01177-w

Background Hepatitis B is known to cause several forms of liver diseases including chronic hepatitis B (CHB), and hepatocellular carcinoma. Previous genome-wide association study of CHB risk has demonstrated that rs12614 of complement factor B (CFB) was significantly associated with CHB risk. In this study, fine-mapping study of previously reported GWAS single nucleotide polymorphism (SNP; CFB rs12614) was performed to validate genetic effect of rs12614 on CHB susceptibility and identify possible additional causal variants around rs12614 in a Korean population. This association study was conducted in order to identify genetic effects of CFB single nucleotide polymorphisms (SNPs) and to identify additional independent CHB susceptible causal markers within a Korean population. Methods A total of 10 CFB genetic polymorphisms were selected and genotyped in 1716 study subjects comprised of 955 CHB patients and 761 population controls. Results A non-synonymous variant, rs12614 (Arg32Trp) in exon2 of CFB, had significant associations with risk of CHB (odds ratio = 0.43, P = 5.91 × 10− 10). Additional linkage disequilibrium and conditional analysis confirmed that rs12614 had independent genetic effect on CHB susceptibility with previously identified CHB markers. The genetic risk scores (GRSs) were calculated and the CHB patients had higher GRSs than the population controls. Moreover, OR was found to increase significantly with cumulative GRS. Conclusions rs12614 showed significant genetic effect on CHB risk within the Korean population. As such rs12614 may be used as a possible causal genetic variant for CHB susceptibility.
Published: 12 December 2020
BMC Medical Genetics, Volume 21, pp 1-6; doi:10.1186/s12881-020-01167-y

Background In Morocco, consanguinity rate is very high; which lead to an increase in the birth prevalence of infants with autosomal recessive disorders. Previously, it was difficult to diagnose rare autosomal recessive diseases. Next Generation Sequencing (NGS) techniques have considerably improved clinical diagnostics. A genetic diagnosis showing biallelic causative mutations is the requirement for targeted carrier testing in parents, prenatal and preimplantation genetic diagnosis in further pregnancies, and also for targeted premarital testing in future couples at risk of producing affected children by a known autosomal recessive disease. Methods In this report, we present our strategy to advise a future couple of first cousins, whose descendants would risk cystinosis; an autosomal recessive lysosomal disease caused by mutations in the CTNS gene. Indeed, our future husband’s sister is clinically and biochemically diagnosed with cystinosis in early childhood. First, we opted to identify the patient’s CTNS gene abnormality by using (NGS), then we searched for heterozygosity in the couple’s DNA, which allows us to predict the exact risk of this familial disease in the future couple’s offspring. Results We have shown that the future husband, brother of the patient is heterozygous for the familial mutation. On the other hand, his future wife did not inherit the familial mutation. Therefore, genetic counseling was reassuring for the risk of familial cystinosis in this couple’s offspring. Conclusions We report in this study, one of the major applications of (NGS), an effective tool to improve clinical diagnosis and to provide the possibility of targeted premarital carrier testing in couples at risk.
Luojia Xu, Weizhong Gu, Youyou Luo, Jingan Lou,
Published: 1 December 2020
BMC Medical Genetics, Volume 21, pp 1-7; doi:10.1186/s12881-020-01164-1

Background Early-onset chronic diarrhoea often indicates a congenital disorder. Mutation in diacylglycerol o-acyltransferase 1 (DGAT1) has recently been linked to early-onset chronic diarrhoea. To date, only a few cases of DGAT1 deficiency have been reported. Diarrhoea in those cases was severe and developed in the neonatal period or within 2 months after birth. Case presentation Here, we report a female patient with DGAT1 mutations with delayed-onset chronic diarrhoea. The patient had vomiting, hypoalbuminemia, hypertriglyceridemia, and failure to thrive at early infancy. Her intractable chronic diarrhoea occurred until she was 8 months of age. A compound heterozygous DGAT1 mutation was found in the patient, which was first found in the Chinese population. Her symptoms and nutrition status improved after nutritional therapy, including a fat restriction diet. Conclusions This case expanded our knowledge of the clinical features of patients with DGAT1 mutations. Intractable diarrhoea with delayed onset could also be a congenital disorder.
, Yaowu Han, Ying Zhang, Yuanfeng Zhou, Lin Ye
Published: 1 December 2020
BMC Medical Genetics, Volume 21, pp 1-1; doi:10.1186/s12881-020-01178-9

An amendment to this paper has been published and can be accessed via the original article.
Mariam Goubran, Ayodeji Aderibigbe, Emmanuel Jacquemin, Catherine Guettier, Safwat Girgis, Vincent Bain,
Published: 30 November 2020
BMC Medical Genetics, Volume 21, pp 1-6; doi:10.1186/s12881-020-01173-0

Background Progressive familial intrahepatic cholestasis (PFIC) type 3 is an autosomal recessive disorder arising from mutations in the ATP-binding cassette subfamily B member 4 (ABCB4) gene. This gene encodes multidrug resistance protein-3 (MDR3) that acts as a hepatocanalicular floppase that transports phosphatidylcholine from the inner to the outer canalicular membrane. In the absence of phosphatidylcholine, the detergent activity of bile salts is amplified and this leads to cholangiopathy, bile duct loss and biliary cirrhosis. Patients usually present in infancy or childhood and often progress to end-stage liver disease before adulthood. Case presentation We report a 32-year-old female who required cadaveric liver transplantation at the age of 17 for cryptogenic cirrhosis. When the patient developed chronic ductopenia in the allograft 15 years later, we hypothesized that the patient’s original disease was due to a deficiency of a biliary transport protein and the ductopenia could be explained by an autoimmune response to neoantigen that was not previously encountered by the immune system. We therefore performed genetic analyses and immunohistochemistry of the native liver, which led to a diagnosis of PFIC3. However, there was no evidence of humoral immune response to the MDR3 and therefore, we assumed that the ductopenia observed in the allograft was likely due to chronic rejection rather than autoimmune disease in the allograft. Conclusions Teenage patients referred for liver transplantation with cryptogenic liver disease should undergo work up for PFIC3. An accurate diagnosis of PFIC 3 is key for optimal management, therapeutic intervention, and avoidance of complications before the onset of end-stage liver disease.
, Varpu Elenius, Heikki Lukkarinen, Tanja Saarela
Published: 26 November 2020
BMC Medical Genetics, Volume 21, pp 1-7; doi:10.1186/s12881-020-01171-2

Background Diagnosis of primary ciliary dyskinesia (PCD) still remains a challenge, especially with mutations in the Dynein Arm Heavy Chain 11 (DNAH11) gene. Classical diagnostic measures like Transmission Electron Microscopy (TEM) are not applicable for mutations in the DNAH11 gene since ultrastructural defects of the ciliary apparatus are absent. Novel mutations encoding for PCD appear all the time with considerable variation in the clinical picture, making it necessary to update data bases and guidelines for PCD diagnostics. Methods In this study we examined two unrelated, Finnish families with symptoms of PCD applying the clinical scoring system: Primary ciliary dyskinesia Rule (PICADAR), high speed video microscopy analysis (HSVMA) for ciliary movement, a commercially available gene panel analysis and nasal Nitric Oxide (nNO) measurements if applicable. Results Two, likely pathogenic variants in the DNAH11 gene (c.2341G > A, p. (Glu781Lys) ja c.7645 + 5G > A) were detected. In the first family, compound heterozygous mutations led to disease manifestation in two of 4 children, which showed a similar phenotype of cilia beating pattern but marked differences in disease severity. In the second family, all three children were homozygotes for the c.2341G > A p.(Glu781Lys) mutation and showed a similar degree of disease severity. However, the phenotype of cilia beating pattern was different ranging from stiff, static cilia to a hyperkinetic movement in one of these children. Conclusions In this study we describe two Finnish families with PCD, revealing two novel mutations in the DNAH11 gene which show considerable variety in the clinical and beating cilia phenotype. The results of this study show the clinician that PCD can be much milder than generally expected and diagnosis demands a combination of measures which are only successful in experienced hands. Chronic and repeatedly treated wet cough should raise suspicion of PCD, referring the patient for further diagnostics to a specialised PCD centre.
, Pascale Mazzola, Tilman Heinrich, Tobias Haack, Bernd Wissinger, Felix Tonagel, Carina Kelbsch
Published: 26 November 2020
BMC Medical Genetics, Volume 21, pp 1-6; doi:10.1186/s12881-020-01166-z

Background Dominant optic atrophy (DOA) is an inherited optic neuropathy that mainly affects visual acuity, central visual fields and color vision due to a progressive loss of retinal ganglion cells and their axons that form the optic nerve. Approximately 45–90% of affected individuals with DOA harbor pathogenic variants in the OPA1 gene. The mutation spectrum of OPA1 comprises nonsense, canonical and non-canonical splice site, frameshift and missense as well as copy number variants, but intragenic inversions have not been reported so far. Case presentation We report a 33-year-old male with characteristic clinical features of DOA. Whole-genome sequencing identified a structural variant of 2.4 kb comprising an inversion of 937 bp at the OPA1 locus. Fine mapping of the breakpoints to single nucleotide level revealed that the structural variation was an inversion flanked by two deletions. As this rearrangement inverts the entire first exon of OPA1, it was classified as likely pathogenic. Conclusions We report the first DOA case harboring an inversion in the OPA1 gene. Our study demonstrates that copy-neutral genomic rearrangements have to be considered as a possible cause of disease in DOA cases.
Ciliu Zhang, Xiaolu Deng, Yafei Wen, Fang He, Fei Yin,
Published: 26 November 2020
BMC Medical Genetics, Volume 21, pp 1-5; doi:10.1186/s12881-020-01162-3

Background Cerebral folate deficiency (CFD) is a neurological disease, hallmarked by remarkable low concentrations of 5-methyltetrahydrofolic acid (5-MTHF) in cerebrospinal fluid (CSF). The primary causes of CFD include the presence of folate receptor (FR) autoantibodies, defects of FR encoding gene FOLR1, mitochondrial diseases and congenital abnormalities in folate metabolism. Case presentation Here we first present a Chinese male CFD patient whose seizure onset at 2 years old with convulsive status epilepticus. Magnetic Resonance Imaging (MRI) revealed the development of encephalomalacia, laminar necrosis in multiple lobes of the brain and cerebellar atrophy. Whole Exome Sequencing (WES) uncovered a homozygous missense variant of c.524G > T (p.C175F) in FOLR1 gene. Further laboratory tests demonstrated the extremely low level of 5-MTHF in the CSF from this patient, which was attributed to cerebral folate transport deficiency. Following the intravenous and oral treatment of calcium folinate, the concentrations of 5-MTHF in CSF were recovered to the normal range and seizure symptoms were relieved as well. Conclusions One novel variation of FOLR1 was firstly identified from a Chinese male patient with tonic-clonic seizures, developmental delay, and ataxia. The WES and laboratory results elucidated the etiology of the symptoms. Clinical outcomes were improved by early diagnosis and proper treatment.
, Adebowale A. Adeyemo, Charles N. Rotimi, Olayinka Olaniyan, Richard Offiong, Clement A. Adebamowo
Published: 23 November 2020
BMC Medical Genetics, Volume 21, pp 1-10; doi:10.1186/s12881-020-01156-1

Background Genetic factors may influence the susceptibility to high-risk (hr) human papillomavirus (HPV) infection and persistence. We conducted the first genome-wide association study (GWAS) to identify variants associated with cervical hrHPV infection and persistence. Methods Participants were 517 Nigerian women evaluated at baseline and 6 months follow-up visits for HPV. HPV was characterized using SPF10/LiPA25. hrHPV infection was positive if at least one carcinogenic HPV genotype was detected in a sample provided at the baseline visit and persistent if at least one carcinogenic HPV genotype was detected in each of the samples provided at the baseline and follow-up visits. Genotyping was done using the Illumina Multi-Ethnic Genotyping Array (MEGA) and imputation was done using the African Genome Resources Haplotype Reference Panel. Association analysis was done for hrHPV infection (125 cases/392 controls) and for persistent hrHPV infection (51 cases/355 controls) under additive genetic models adjusted for age, HIV status and the first principal component (PC) of the genotypes. Results The mean (±SD) age of the study participants was 38 (±8) years, 48% were HIV negative, 24% were hrHPV positive and 10% had persistent hrHPV infections. No single variant reached genome-wide significance (p < 5 X 10− 8). The top three variants associated with hrHPV infections were intronic variants clustered in KLF12 (all OR: 7.06, p = 1.43 × 10− 6). The top variants associated with cervical hrHPV persistence were in DAP (OR: 6.86, p = 7.15 × 10− 8), NR5A2 (OR: 3.65, p = 2.03 × 10− 7) and MIR365–2 (OR: 7.71, p = 2.63 × 10− 7) gene regions. Conclusions This exploratory GWAS yielded suggestive candidate risk loci for cervical hrHPV infection and persistence. The identified loci have biological annotation and functional data supporting their role in hrHPV infection and persistence. Given our limited sample size, larger discovery and replication studies are warranted to further characterize the reported associations.
Babunageswararao Kanuri, Vincent Fong, April Haller, David Y. Hui,
Published: 23 November 2020
BMC Medical Genetics, Volume 21, pp 1-9; doi:10.1186/s12881-020-01176-x

Background Autosomal dominant familial hypercholesterolemia (ADH; MIM#143890) is one of the most common monogenic disorders characterized by elevated circulatory LDL cholesterol. Initial studies in humans with ADH identified a potential relationship with variants of the gene encoding signal transducing adaptor family member protein 1 (STAP1; MIM#604298). However, subsequent studies have been contradictory. In this study, mice lacking global Stap1 expression (Stap1−/−) were characterized under standard chow and a 42% kcal western diet (WD). Methods Mice were studied for changes in different metabolic parameters before and after a 16-week WD regime. Growth curves, body fats, circulatory lipids, parameters of glucose homeostasis, and liver architecture were studied for comparisons. Results Surprisingly, Stap1−/− mice fed the 16-week WD demonstrated no marked differences in any of the metabolic parameters compared to Stap1+/+ mice. Furthermore, hepatic architecture and cholesterol content in FPLC-isolated lipoprotein fractions also remained comparable to wild-type mice. Conclusion These results strongly suggest that STAP1 does not alter lipid levels, that a western diet did not exacerbate a lipid disorder in Stap1 deficient mice and support the contention that it is not causative for hyperlipidemia in ADH patients. These results support other published studies also questioning the role of this locus in human hypercholesterolemia.
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