Fetal Congenital Heart Disease Caused by Compound Heterozygous Mutations in the DNAH9 Gene: A Case Report
Tao ZhangHua YuanHongdan ZhuYuyi YingJinlong DingHaigang DingXiaoliang ShiYao HeHaitao PanYong-Xing Zhong
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Background: Fetal congenital heart disease (CHD) is the most common congenital defect, with an incidence of 0.6-0.8%, accounting for 30-50% of infant congenital disease deaths. The pathogenesis of CHD is still unclear, so an active and effective prenatal diagnosis is very important for the prevention and control of CHD. Herein, a Chinese CHD patient with rare compound heterozygous mutations in the DNAH9 gene was reported, and the 3D structure and functional changes of DNAH9 protein were predicted. Case presentation: A 23-year-old pregnant woman came to our hospital for prenatal diagnosis at 27 weeks of gestation. Both she and her partner were unaffected. Fetal CHD was detected by ultrasound screening. Copy number variation sequencing (CNV-seq) revealed an 81 kb deletion at chr17p12 (11,486,795-11,568,385), including exons 1-15 of DNAH9 gene, which plays a key role in cardiac development. Then, whole exome sequencing (WES) was used and identified a nonsense mutation (c.10975C>T) in DNAH9, which resulted in the mutation of amino acid 3,659 from glutamine to termination. The 3D mutant protein structures were predicted using SWISS-MODEL and showed structural changes from functional β-sheet and α-helix to termination, respectively. Conclusion: We describe a case of fetal CHD caused by DNAH9 mutations and provide an effective diagnostic technique for identifying intragenic deletions. This diagnostic process can be implicated in prenatal diagnosis of CHD.Keywords:
Compound heterozygosity
Nonsense mutation
Fetal echocardiography
Lipoid proteinosis (LP) is a rare autosomal recessive genodermatosis caused by mutations of the ECM1 gene. The common variations of the ECM1 gene are nonsense and missense mutations, and in rare instance, compound heterozygotes may occur. We describe two siblings of LP from a nonconsanguineous family of China who were detected novel compound heterozygous mutations of c. 157C >T(p. R53X) in exon 3 and c. 857G >A (p. C286Y) in exon 7 of the ECM1 gene. Their mother was a carrier of missense mutation of c. 857G >A in exon 7 of ECM1, their father and one of the old sisters were the carriers of nonsense mutation of c. 157C >T in exon 3, respectively. All the carriers presented normally. The results support the opinion that the mutations of the ECM1 gene for LP are of varieties.
Compound heterozygosity
Nonsense mutation
Genodermatosis
Nonsense
Chinese family
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Abstract Purpose: This study was designed to identify the underlying molecular genetic cause of idiopathic hypogonadotropic hypogonadism (IHH) in a nonconsanguineous Chinese family. Methods: All the family members underwent medical history evaluation, physical examination, and laboratory studies. Whole-exome sequencing and RNA sequencing was performed on 2 affected siblings and unaffected parents. All candidate variants were confirmed in all family members by Sanger sequencing and silico function prediction. Results: The proband and his twin brother were diagnosed with IHH, and an autosomal recessive mode of inheritance was identified. Whole-exome sequencing identified the compound heterozygous variants c.9230G>A (p.Arg3077Gln) and c.12883G>A (p.Val4295Met) in DNAH5 in both affected siblings. Sanger sequencing verified that c.9230G>A in DNAH5 was from the unaffected mother and c.12883G>A was from the unaffected father. In addition, we found heterozygous mutations in BBS2 (c.1705delC, p.Gln569fs) and NR5A1 (c.460G>A, p.Ala154Thr) in the siblings, which were from their father. Conclusion: Compound heterozygous variants in DNAH5 were identified in the affected siblings, and were predicted to be pathogenic by silico analysis. This is the first report that suggests variants in DNAH5 are relevant to the pathogenesis of IHH. This study expands the variant spectrum of genes associated with IHH.
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Abstract Clinical diagnosis of autoinflammatory diseases requires a high degree of clinical suspicion and clinching molecular evidence to substantiate the diagnosis. This is more so in populations with low prevalence of these disorders. In this report, we describe the case of a young man from India with recurrent fever and persistent arthritis. The patient's forefathers were of Egyptian ancestry who practiced consanguinity. Molecular genetic analysis using whole‐exome sequencing suggested the presence of variants c.443A>T:p.E148V and c.442G>C:p.E148Q in the MEFV gene, earlier independently shown to be associated with familial Mediterranean fever ( FMF ) in a compound heterozygous state. The variants were further confirmed by capillary sequencing. This report also highlights the application of whole exome sequencing to delineate the allelic differences in the variants apart from serving as a quick genetic screening approach for autoinflammatory diseases. To the best of our knowledge, this is the first report of a compound heterozygosity for the two well‐characterized variants associated with atypical FMF in a patient.
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Pendred syndrome (PDS, MIM #274600) is an autosomal recessive disorder characterized by congenital sensorineural hearing loss and goiter. In this study, we describing the possible PDS causal mutations in a Malaysian family with 2 daughters diagnosed with bilateral hearing loss and hypothyroidism. Whole exome sequencing was performed on 2 sisters with PDS and their unaffected parents. Our results showed that both sisters inherited monoallelic mutations in the 2 known PDS genes, SLC26A4 (ENST00000265715:c.1343C > T, p.Ser448Leu) and GJB2 (ENST00000382844:c.368C > A, p.Thr123Asn) from their father, as well as another deafness-related gene, SCARB2 (ENST00000264896:c.914C > T, p.Thr305Met) from their mother. We postulated that these three heterozygous mutations in combination may be causative to deafness, and warrants further investigation. Furthermore, we also identified a compound heterozygosity involving the DUOX2 gene (ENST00000603300:c.1588A > T:p.Lys530* and c.3329G > A:p.Arg1110Gln) in both sisters which are inherited from both parents and may be correlated with early onset of goiter. All the candidate mutations were predicted deleterious by in silico tools. In summary, we proposed that PDS in this family could be a polygenic disorder which possibly arises from a combination of heterozygous mutations in SLC26A4, GJB2 and SCARB2 which associated with deafness, as well as compound heterozygous DUOX2 mutations which associated with thyroid dysfunction.
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Friedreich's ataxia is a neurodegenerative disorder associated with a GAA trinucleotide repeat expansion in intron 1 of the frataxin (FXN) gene. It is the most common autosomal recessive cerebellar ataxia, with a mean age of onset at 16 years. Nearly 95-98% of patients are homozygous for a 90-1300 GAA repeat expansion with only 2-5% demonstrating compound heterozygosity. Compound heterozygous individuals have a repeat expansion in one allele and a point mutation/deletion/insertion in the other. Compound heterozygosity and point mutations are very rare causes of Friedreich's ataxia and nonsense mutations are a further rarity among point mutations. We report a rare compound heterozygous Friedrich's ataxia patient who was found to have one expanded GAA FXN allele and a nonsense point mutation in the other. We summarize the four previously published cases of nonsense mutations and compare the phenotype to that of our patient. We compared clinical information from our patient with other nonsense FXN mutations reported in the literature. This nonsense mutation, to our knowledge, has only been described once previously; interestingly the individual was also of Cuban ancestry. A comparison with previously published cases of nonsense mutations demonstrates some common clinical characteristics.
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Compound heterozygosity
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Frataxin
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Nonsense mutation
Compound heterozygosity
Heterozygote advantage
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Congenital muscular dystrophy
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Abstract Background Intellectual disability is a prevalent neurodevelopmental disorder, with the majority of affected children exhibiting global developmental delay before the age of 5 years. In recent years, certain children have been found to carry homozygous variations of the EEF1D gene, leading to autosomal recessive intellectual disability. However, the pathogenicity of compound heterozygous variations in this gene remains largely unknown. Methods Trio whole‐exome sequencing and copy number variation sequencing were done for the genetic etiological diagnosis of a 3‐year and 11‐month‐old Chinese boy who presented with brachycephaly, severe to profound global developmental delay, and hypotonia in the lower limbs. Results In this case, compound heterozygous variants of the EEF1D gene were found in the child through trio whole‐exome sequencing; one was a splice variant (NM_032378.6:c.1905+1G>A) inherited from his father, and the other was a nonsense variant (NM_032378.6:c.676C>T) inherited from his mother. The nonsense variant leads to the production of a premature termination (p.Gln226*). These variations have the ability to explain the clinical phenotypes of the child. Conclusions Our study expands the variation spectrum and provides compelling evidence for EEF1D as a candidate gene for autosomal recessive intellectual disability. However, due to the deficient number of reported cases, researchers need to further study EEF1D and supplement the clinical phenotypes and treatment measures.
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Nonsense
Global developmental delay
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Speech delay
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Abstract SMG9-deficiency syndrome, also known as heart and brain malformation syndrome, is a very rare congenital genetic disorder mainly characterized by brain, heart, and growth and developmental abnormalities. This syndrome is an autosomal recessive disease resulting from mutations in the SMG9 gene, which encodes a critical component of nonsense-mediated mRNA decay. Thus far, only twelve SMG9 deficiency patients have been reported with five novel homozygous SMG9 mutations. The most frequent characteristic features of these patients are facial dysmorphism, severe global developmental delay, intellectual disability, congenital heart disease, growth restriction, microcephaly, and brain abnormalities. Herein, whole exome sequencing was performed to identify novel compound heterozygous SMG9 variants (NM_019108.3: c.1318_1319delAG (p.Ser440*) and c.947A>G (p.His316Arg)) in the proband, who exhibited syndromic intellectual disability. Mutations were confirmed as segregating in his affected sister and other unaffected family members by Sanger sequencing. The patients we describe here have a similar dysmorphology profile associated with SMG9-deficiency syndrome. Comparing the phenotype with that of patients in published reports, our patients can walk independently and their growth parameters are normal. In addition, short stature, failure to thrive, and microcephaly were not observed. Possible residual function of the H316R SMG9 variant could explain the milder phenotype observed in our patients. Our report is the first description of a non-consanguineous Chinese pedigree with novel compound heterozygous variants in the SMG9 gene. The molecular confirmation of the patient expands the genetic spectrum of SMG9-deficiency syndrome, and the manifestation of SMG9-deficiency syndrome in the patient provides additional clinical information regarding this syndrome.
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Microcephaly
Sanger sequencing
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Global developmental delay
Nonsense mutation
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Sanger sequencing
Nonsense mutation
Stop codon
Exome
Nonsense
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Acrodermatitis enteropathica is rare autosomal recessive disorder characterized by a severe nutritional zinc deficiency. We and others have recently identified the human gene encoding an intestinal zinc transporter of the ZIP family, SLC39A4, as the mutated gene in acrodermatitis enteropathica (AE). A first mutation screening in 8 AE families (15 patients out of 36 individuals) revealed the presence of six different mutations described elsewhere. Based on these results, we have evaluated the involvement of SLC39A4 in 14 patients of 12 additional AE pedigees coming either from France, Tunisia, Austria or Lithuania. A total of 7 SLC39A4 mutations were identified (1 deletion, 2 nonsense, 2 missense, and 2 modifications of splice site), of which 4 are novel: a homozygous nonsense mutation in 3 consanguineous Tunisian families [c.143T>G (p.Leu48X)], a heterozygous nonsense mutation (c.1203G>A (p.Trp401X)) in a compound heterozygote from Austria also exhibiting an already known missense mutation, and distinct homozygous mutations in families from France or Tunisia [c.475-2A>G and c.184T>C (p.Cys62Arg)]. Furthermore, two other potential mutations [c.850G>A (p.Glu284Lys) and c.193-113T>C] were also observed at homozygous state in a French family formerly described. This study brings to 21 the number of reported SLC39A4 mutations in AE families.
Acrodermatitis enteropathica
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