Compound Heterozygous Research Articles

CIAO1 and MMS19 deficiency: A lethal neurodegenerative phenotype caused by cytosolic Fe-S cluster protein assembly disorders

PurposeThe functionality of many cellular proteins depends on cofactors; yet, they have only been implicated in a minority of Mendelian diseases. Here, we describe the first 2 inherited disorders of the cytosolic iron-sulfur protein assembly system. MethodsGenetic testing via genome sequencing was applied to identify the underlying disease cause in 3 patients with microcephaly, congenital brain malformations, progressive developmental and neurologic impairments, recurrent infections, and a fatal outcome. Studies in patient-derived skin fibroblasts and zebrafish models were performed to investigate the biochemical and cellular consequences. ResultsMetabolic analysis showed elevated uracil and thymine levels in body fluids but no pathogenic variants in DPYD, encoding dihydropyrimidine dehydrogenase. Genome sequencing identified compound heterozygosity in 2 patients for missense variants in CIAO1, encoding cytosolic iron-sulfur assembly component 1, and homozygosity for an in-frame 3-nucleotide deletion in MMS19, encoding the MMS19 homolog, cytosolic iron-sulfur assembly component, in the third patient. Profound alterations in the proteome, metabolome, and lipidome were observed in patient-derived fibroblasts. We confirmed the detrimental effect of deficiencies in CIAO1 and MMS19 in zebrafish models. ConclusionA general failure of cytosolic and nuclear iron-sulfur protein maturation caused pleiotropic effects. The critical function of the cytosolic iron-sulfur protein assembly machinery for antiviral host defense may well explain the recurrent severe infections occurring in our patients.

Phenotypic variation of FXN compound heterozygotes in a Friedreich ataxia cohort.

Most individuals with Friedreich ataxia (FRDA) have homozygous GAA triplet repeat expansions in the FXN gene, correlating with a typical phenotype of ataxia and cardiomyopathy. A minority are compound heterozygotes carrying a GAA expansion on one allele and a mutation on the other. The study aim was to examine phenotypic variation among compound heterozygotes. Data on FXN mutations were obtained from the Friedreich Ataxia Clinical Outcome Measures Study (FA-COMS). We compared clinical features in a single-site FA-COMS cohort of 51 compound heterozygous and 358 homozygous patients, including quantitative measures of cardiac, neurologic, and visual disease progression. Non-GAA repeat mutations were associated with reduced cardiac disease, and patients with minimal/no function mutations otherwise had a typical FRDA phenotype but with significantly more severe progression. The partial function mutation group was characterized by relative sparing of bulbar and upper limb function, as well as particularly low cardiac involvement. Other clinical features in this group, including optic atrophy and diabetes mellitus, varied widely depending on the specific type of partial function mutation. These data support that the typical FRDA phenotype is driven by frataxin deficiency, especially severe in compound heterozygotes with minimal/no function mutations, whereas the heterogeneous presentations of those with partial function mutations may indicate other contributing factors to FRDA pathogenesis.

Bioinformatics characterization of variants of uncertain significance in pediatric sensorineural hearing loss.

Rapid advancements in Next Generation Sequencing (NGS) and bioinformatics tools have allowed physicians to obtain genetic testing results in a more rapid, cost-effective, and comprehensive manner than ever before. Around 50% of pediatric sensorineural hearing loss (SNHL) cases are due to a genetic etiology, thus physicians regularly utilize targeted sequencing panels that identify variants in genes related to SNHL. These panels allow for early detection of pathogenic variants which allows physicians to provide anticipatory guidance to families. Molecular testing does not always reveal a clear etiology due to the presence of multigenic variants with varying classifications, including the presence of Variants of Uncertain Significance (VUS). This study aims to perform a preliminary bioinformatics characterization of patients with variants associated with Type II Usher Syndrome in the presence of other multigenic variants. We also provide an interpretation algorithm for physicians reviewing molecular results with medical geneticists. Review of records for multigenic and/or VUS results identified several potential subjects of interest. For the purposes of this study, two ADGRV1 compound heterozygotes met inclusion criteria. Sequencing, data processing, and variant calling (the process by which variants are identified from sequence data) was performed at Invitae (San Francisco CA). The preliminary analysis followed the recommendations outlined by the American College of Medical Genetics and Association for Molecular Pathology (ACMG-AMP) in 2015 and 2019. The present study utilizes computational analysis, predictive data, and population data as well as clinical information from chart review and publicly available information in the ClinVar database. Two subjects were identified as compound heterozygotes for variants in the gene ADGRV1. Subject 1's variants were predicted as deleterious, while Subject 2's variants were predicted as non-deleterious. These results were based on known information of the variants from ClinVar, multiple lines of computational data, population databases, as well as the clinical presentation. Early molecular diagnosis through NGS is ideal, as families are then able to access a wide range of resources that will ultimately support the child as their condition progresses. We recommend that physicians build strong relationships with medical geneticists and carefully review their interpretation before making recommendations to families, particularly when addressing the VUS. Reclassification efforts of VUS are supported by studies like ours that provide evidence of pathogenic or benign effects of variants.

Low frequency of SLC26A4 c.919-2A > G variant among patients with nonsyndromic hearing loss in Yunnan of Southwest China

BackgroundGene variants are responsible for more than half of hearing loss, particularly in nonsyndromic hearing loss (NSHL). The most common pathogenic variant in SLC26A4 gene found in East Asian populations is c.919-2A > G followed by c.2168A > G (p.H723R). This study was to evaluate their variant frequencies in patients with NSHL from special education schools in nine different areas of Southwest China’s Yunnan.MethodsWe performed molecular characterization by PCR-products directly Sanger sequencing of the SLC26A4 c.919-2AG and c.2168 A > G variants in 1167 patients with NSHL including 533 Han Chinese and 634 ethnic minorities.ResultsThe SLC26A4 c.919-2A > G variant was discovered in 8 patients with a homozygous state (0.69%) and twenty-five heterozygous (2.14%) in 1167 patients with NSHL. The total carrier rate of the c.919-2A > G variant was found in Han Chinese patients with 4.50% and ethnic minority patients with 1.42%. A significant difference existed between the two groups (P < 0.05). The c.919-2A > G allele variant frequency was ranged from 3.93% in Kunming to zero in Lincang and Nvjiang areas of Yunnan. We further detected the SLC26A4 c.2168 A > G variant in this cohort with one homozygotes (0.09%) and seven heterozygotes (0.60%), which was detected in Baoshan, Honghe, Licang and Pu`er areas. Between Han Chinese group (0.94%) and ethnic minority group (0.47%), there was no statistical significance (P > 0.05). Three Han Chinese patients (0.26%) carried compound heterozygosity for c.919-2A > G and c.2168 A > G.ConclusionThese data suggest that the variants in both SLC26A4 c.919-2A > G and c.2168 A > G were relatively less frequencies in this cohort compared to the average levels in most regions of China, as well as significantly lower than that in Han-Chinese patients. These results broadened Chinese population genetic information resources and provided more detailed information for regional genetic counselling for Yunnan.

Establishment of a non-integrated iPSC line (SDQLCHi043-A) from a male infant with propionic acidemia carrying compound heterozygote mutations in PCCB gene

In this study, peripheral blood mononuclear cells were contributed from a male infant with propionic acidemia (PA) verified by clinical and genetic diagnosis, who inherited compound heterozygous mutations in the propionyl-CoA carboxylase subunit beta (PCCB) gene. Here, this iPS was generated by non-integrated episomal vectors with SOX2, BCL-XL, OCT4, C-MYC and OCT4. Also, this iPSC line exhibited the morphology of pluripotent stem cells, upward mRNA and protein expression of pluripotency markers, conspicuous in vitro differentiation potency and regular karyotype, and carried PCCB gene mutations, which provided an excellent model for the research and drug screening of PA.

ALDH18A1‐related hereditary spastic paraplegia and developmental and epileptic encephalopathy with spike‐wave activation in sleep: Expanding the clinical phenotype

AbstractObjectiveWe present the cases of two sisters, both harboring the same ALDH18A1 gene mutations, who presented with a complex clinical phenotype characterized by spastic paraparesis with ataxia, epileptic encephalopathy, severe psychomotor deficits, and behavioral abnormalities.MethodsCase description of two sisters with ALDH18A1 gene mutations.ResultsThe older patient, a 12‐year‐old girl, exhibited spastic paraparesis with ataxia, microcephaly, facial dysmorphisms, and severe intellectual disability, with an absence of verbal language. An electroencephalogram (EEG) revealed marked spike‐and‐wave activation during sleep (SWAS), although no clinically documented seizures were observed. The younger sister, who was 9 years old, displayed a similar clinical presentation, including spastic paraparesis with ataxia, microcephaly, dysmorphisms, however, she displayed slightly more severe intellectual deficits and polymorphic seizures. EEG revealed a SWAS pattern in this case. Magnetic resonance imaging scans in both cases showed only a thin corpus callosum. Whole exome sequencing unveiled the presence of two likely pathogenic variants in compound heterozygosity within the ALDH18A1 gene. Specifically, these variants included the splice site variant c.88 + 1c.88+1G&gt;A of paternal origin and the variant c.1364c.1364T&gt;C (p.Leu455Ser) of maternal origin. Both sisters displayed normal blood levels of ammonia, ornithine, citrulline, arginine, and other amino acids.InterpretationThese findings were compatible with ALDH18A1‐related HSP complicated with a clinical and EEG pattern reminiscent of DEE‐SWAS. We present the first report of DEE‐SWAS in ALDH18A1‐related HSP, expanding the clinical manifestations of this complex neurodevelopmental condition.

Mutations of GEMIN5 are associated with coenzyme Q10 deficiency: long-term follow-up after treatment.

GEMIN5 exerts key biological functions regulating pre-mRNAs intron removal to generate mature mRNAs. A series of patients were reported harboring mutations in GEMIN5. No treatments are currently available for this disease. We treated two of these patients with oral Coenzyme Q10 (CoQ10), which resulted in neurological improvements, although MRI abnormalities remained. Whole Exome Sequencing demonstrated compound heterozygosity at the GEMIN5 gene in both cases: Case one: p.Lys742* and p.Arg1016Cys; Case two: p.Arg1016Cys and p.Ser411Hisfs*6. Functional studies in fibroblasts revealed a decrease in CoQ10 biosynthesis compared to controls. Supplementation with exogenous CoQ10 restored it to control intracellular CoQ10 levels. Mitochondrial function was compromised, as indicated by the decrease in oxygen consumption, restored by CoQ10 supplementation. Transcriptomic analysis of GEMIN5 patients compared with controls showed general repression of genes involved in CoQ10 biosynthesis. In the rigor mortis defective flies, CoQ10 levels were decreased, and CoQ10 supplementation led to an improvement in the adult climbing assay performance, a reduction in the number of motionless flies, and partial restoration of survival. Overall, we report the association between GEMIN5 dysfunction and CoQ10 deficiency for the first time. This association opens the possibility of oral CoQ10 therapy, which is safe and has no observed side effects after long-term therapy.

Audiological Phenotypes of Connexin Gene Mutation Patterns: A Glance at Different GJB2/GJB6 Gene Mutation Profiles.

GJB2 mutations are the most common cause of autosomal-recessive non-syndromic sensorineural hearing loss (SNHL). The available evidence shows large phenotypic variability across different genotypes and allelic variants. The aim of this study was to investigate the clinical and audiological features of a cohort of subjects with different GJB2/GJB6 gene mutation profiles from a tertiary referral center in Northeastern Italy. We considered 57 patients with GJB2/GJB6 mutations presenting with congenital, non-syndromic SNHL, mainly coming from the Veneto region (Italy). The samples were screened for mutations in exons 1 and 2 of the GJB2 gene and for the GJB6 gene deletion del (GJB6-D13S1830). Free-field and air-conduction frequency-specific thresholds and the pure-tone average (PTA) were considered in the statistical analysis. Five patients (8.87%) had connexin gene mutations in simple heterozygosis, 15 (26.31%) in compound heterozygosis, 34 (59.64%) in homozygosis, and 3 (5.26%) with digenic patterns. The frequency-specific air-conduction thresholds showed significantly different mean values across the different genotypes (Roy's largest-root test, p = 0.0473). Despite the evidence already available on genetic SNHL, many new insights are to be expected. Further large-scale prospective studies including different populations are necessary to confirm these preliminary findings about the clinical and audiological features of patients with different GJB2/GJB6 gene mutation patterns.

Phenome-wide analysis reveals epistatic associations between APOL1 variants and chronic kidney disease and multiple other disorders

APOL1 variants G1 and G2 are common in populations with recent African ancestry. They are associated with protection from African sleeping sickness, however homozygosity or compound heterozygosity for these variants is associated with chronic kidney disease (CKD) and related conditions. What is not clear is the extent of associations with non-kidney-related disorders, and whether there are clusters of diseases associated with individual APOL1 genotypes. Using a cohort of 7462 UK Biobank participants with recent African ancestry, we conducted a phenome-wide association study investigating associations between individual APOL1 genotypes and conditions identified by the International Classification of Disease phenotypes. We identified 27 potential associations between individual APOL1 genotypes and a diverse range of conditions. G1/G2 compound heterozygotes were specifically associated with 26 of these conditions (all deleteriously), with an over-representation of infectious diseases (including hospitalisation and death resulting from COVID-19). The analysis also exposed complexities in the relationship between APOL1 and CKD that are not evident when risk variants are grouped together: G1 homozygosity, G2 homozygosity, and G1/G2 compound heterozygosity were each shown to be associated with distinct CKD phenotypes. The multi-locus nature of the G1/G2 genotype means that its associations would go undetected in a standard genome-wide association study. Our findings have implications for understanding health risks and better-targeted detection, intervention, and therapeutic strategies, particularly in populations where APOL1 G1 and G2 are common such as in sub-Saharan Africa and its diaspora. This study was funded by the Wellcome Trust (209511/Z/17/Z) and H3Africa (H3A/18/004).

Unravelling the Complexity of the +33 C>G [HBB:c.-18C>G] Variant in Beta Thalassemia.

The +33 C>G variant [NM_000518.5(HBB):c.-18C>G] in the 5' untranslated region (UTR) of the β-globin gene is described in the literature as both mild and silent, while it causes a phenotype of thalassemia intermedia in the presence of a severe β-thalassemia allele. Despite its potential clinical significance, the determination of its pathogenicity according to established standards requires a greater number of published cases and co-segregation evidence than what is currently available. The present study provides an extensive phenotypic characterization of +33 C>G using 26 heterozygous and 11 compound heterozygous novel cases detected in Cyprus and employs computational predictors (CADD, RegulomeDB) to better understand its impact on clinical severity. Genotype identification of globin gene variants, including α- and δ-thalassemia determinants, and rs7482144 (XmnI) was carried out using Sanger sequencing, gap-PCR, and restriction enzyme digestion methods. The heterozygous state of +33 C>G had a silent phenotype without apparent microcytosis or hypochromia, while compound heterozygosity with a β+ or β0 allele had a spectrum of clinical phenotypes. Awareness of the +33 C>G is required across Mediterranean populations where β-thalassemia is frequent, particularly in Cyprus, with significant relevance in population screening and fetal diagnostic applications.

Splenic abscess, a rare complication in a case of sickle cell thalassemia

Sickle cell disease (SCD) is an inherited autosomal recessive haemoglobinopathy. Sickle cell beta thalassemia is a variant syndrome of SCD characterised by the compound heterozygosity for sickle and beta thalassemia genes. We present a case of 12 year old male child diagnosed case of sickle cell thalassemia at the age of 2 years with complaints of fever, yellowish discolouration of eyes and drowsiness. USG abdomen was done suggestive of splenomegaly, multiple ill-defined, heterogeneously hypo-echoic, areas scattered throughout the splenic parenchyma with no vascularity within likely representing as splenic micro-abscesses. Child was started on antibiotics covering anaerobic and gram-positive organisms (vancomycin, meropenem, amikacin and metronidazole). Currently child is doing well with huge relieve to his symptoms.

The first case of intellectual disability caused by novel compound heterozygosity for NUDT2 variants

NUDT2 is an enzyme important for maintaining the intracellular level of the diadenosine tetraphosphate (Ap4A). Bi-allelic loss of function variants in NUDT2 has recently been reported as a rare cause of intellectual disability (ID). Herein, we describe a Chinese girl with ID, attention deficit hyperactivity disorder (ADHD), and motor delays with abnormal walking posture and difficulty climbing stairs, who bears compound heterozygous variants c.34 C > T (p.R12*) and c.194T > G (p.I65R) in NUDT2. Homozygous variants c.34 C > T (p.R12*) or c.186del (p.A63Qfs*3) in NUDT2 were previously reported to cause ID. This is the first patient with ID due to compound heterozygous variants in NUDT2 and p.I65R is a novel missense variant. This study enriched the genotype and phenotype of NUDT2-related ID and supported the critical developmental involvement of NUDT2.

Sodium Channel Gene Variants in Fetuses with Abnormal Sonographic Findings: Expanding the Prenatal Phenotypic Spectrum of Sodium Channelopathies.

Voltage-gated sodium channels (VGSCs) are responsible for the initiation and propagation of action potentials in the brain and muscle. Pathogenic variants in genes encoding VGSCs have been associated with severe disorders including epileptic encephalopathies and congenital myopathies. In this study, we identified pathogenic variants in genes encoding the α subunit of VGSCs in the fetuses of two unrelated families with the use of trio-based whole exome sequencing, as part of a larger cohort study. Sanger sequencing was performed for variant confirmation as well as parental phasing. The fetus of the first family carried a known de novo heterozygous missense variant in the SCN2A gene (NM_001040143.2:c.751G>A p.(Val251Ile)) and presented intrauterine growth retardation, hand clenching and ventriculomegaly. Neonatally, the proband also exhibited refractory epilepsy, spasms and MRI abnormalities. The fetus of the second family was a compound heterozygote for two parentally inherited novel missense variants in the SCN4A gene (NM_000334.4:c.4340T>C, p.(Phe1447Ser), NM_000334.4:c.3798G>C, p.(Glu1266Asp)) and presented a severe prenatal phenotype including talipes, fetal hypokinesia, hypoplastic lungs, polyhydramnios, ear abnormalities and others. Both probands died soon after birth. In a subsequent pregnancy of the latter family, the fetus was also a compound heterozygote for the same parentally inherited variants. This pregnancy was terminated due to multiple ultrasound abnormalities similar to the first pregnancy. Our results suggest a potentially crucial role of the VGSC gene family in fetal development and early lethality.

High-Oxygen-Affinity Hemoglobins-Case Series and Review of the Literature.

Modifications of the hemoglobin (Hb) structure in regions involving the regulation of oxygen transport may lead to an increased oxygen affinity for the hemoglobin molecule and impaired oxygen delivery to the tissues. Herein, we present six patients with high-oxygen-affinity Hb variants, either in heterozygous form or in compound heterozygosity (such as heterozygosity for Hb Hiroshima, Köln, Crete, and compound heterozygosity Hb Crete with β or δβ thalassemia), in order to demonstrate the need for prompt and accurate diagnosis and enrich the limited literature due to the rarity of such cases. Hb Crete, Hb Hiroshima, and Hb Köln have distinct pathophysiologies and may result in different clinical phenotypes. In conclusion, high-oxygen-affinity hemoglobins are rare and inherited within a dominant autosomal manner, have various clinical presentations, and should always be suspected in patients with erythrocytosis. Their management (as phlebotomy or low-dose aspirin) should be based on an individualized assessment of the risk of complications, the medical history, concomitant symptoms, and quality of life.

Schwartz-Jampel Syndrome Type-1: Compound Heterozygosity of Two Novel Variants.

Schwartz-Jampel Syndrome (SJS) type-1 (OMIM; #255800), a rare cause of skeletal dysplasia, is characterized by myotonic myopathy, chondrodystrophy, short stature, facial and eye abnormalities. SJS Type-1 develops due to variations in the HSPG2 gene which produces the "perlecan" molecule, one of the main proteoglycans of the basement membrane. A 6-year-old girl presented with short stature, a mask face, shrunken lips, narrow palpebral opening due to blepharospasm, stiffness of facial muscles, micrognathia, overlapping teeth, a short neck, and a bell-shaped thorax due to myotonic myopathy. She was diagnosed with SJS type-1 due to compound heterozygosity of two novel variations in the HSPG2 gene. In patients with short stature and an accompanying myotonic myopathy SJS should be considered. Compound heterozygosity may cause typical clinical findings of SJS. In case of suspicion creatinine kinase levels can be measured, and the determination of myotonia may require evaluation with electromyography. Once the diagnosis is made, patients should be carefully monitored in terms of growth, neuromuscular disorders, joints problems and bone health.

Novel cis compound heterozygous variants in MYO6 causes early onset of non-syndromic hearing loss in a Chinese family.

Background: Mutations in the MYO6 gene have been associated with both autosomal dominant non-syndromic hearing loss (ADNSHL) and autosomal recessive non-syndromic hearing loss (ARNSHL), with a cumulative identification of 125 pathogenic variants. To investigate the underlying genetic factor within a Chinese family affected with heriditary hearing loss, prompted the utilization of high-throughput sequencing. Method: A detailed clinical investigation was performed. Genetic testing was performed by using target panel sequencing, and Sanger sequencing. Targeted sequencing identified the variants and Sanger sequencing was employed to validate segregation of the identified variants within family. Additionally, bioinformatics analysis was performed to strengthen our findings. Results: Clinical investigation revealed the family members were affected by progressive and sensorineural hearing loss with an onset around 8-10 years old. Furthermore, genetic testing identified novel MYO6 variants, c.[2377T>G; 2382G>T] p.[Trp793Gly; Lys794Asn], positioned in a cis pattern, as plausible pathogenic contributors to early-onset hearing loss characterized by a severe and progressive course. Moreover, bioinformatics analysis showd disruptin in hydrogen bonding of mutant amino acids with interactive amino acids. Conclusion: Our research uncovered a relationship between mutations in the MYO6 gene and non-syndromic hearing loss. We identified two variants, c.[2377T>G; 2382G>T] p.[Trp793Gly; Lys794Asn] in MYO6 as strong candidates responsible for the observed progressive hereditary hearing loss. This study not only adds to our knowledge about hearing problems related to MYO6 but also reveals the presence of monogenic compound heterozygosity. Our study will provide a new sight for genetic diagnosis in such patients and their management for future use.

Early versus late diagnosis of LAMA2 congenital muscular dystrophy: a distinct consequence

BackgroundLaminin subunit alpha 2 (LAMA2)-related muscular dystrophy (LAMA2 MD) is caused by homozygous or compound heterozygous mutations in LAMA2 (OMIM#156225), located on chromosome 6q22.Case presentationWe describe two patients with LAMA2 MD treated at a Taiwanese hospital. Both presented with gradual hypotonia starting in early infancy. A targeted muscular dystrophy/myopathy panel and whole-exome sequencing were used as diagnostic tools in both patients. In Patient 1, a maternally inherited variant (NM_000426.3:c.7525_7528dupCTCA/ p.Ser2510ThrfsTer3) and a paternally inherited variant (c.112 + 2 T > C) were revealed. In Patient 2, compound heterozygote mutations in LAMA2 were identified: 1) c.1583dupA(p.S529Efs*18) in exon 11, inherited paternally, and 2) c.A6931T:p.K2311X in exon 49, inherited maternally. The discovery of these four mutations enriches the genetic spectrum of LAMA2 MD.ConclusionsWe suggest that comprehensive genetic investigations be performed as early as possible in patients with suspected muscular dystrophy to provide appropriate treatment.

Non-transfusion dependent HbE/βO-thalassemia as the results of co-existent SEA-αO thalassemia, Hb Constant Spring, and XmnI-Gγ site: Thai family studies

Background: Four university students of northern Thai descent were found to be HbE/βO-thalassemia. However, they all had a mild form of this disease, categorized as Non-Transfusion Dependent Thalassemia. Objectives: To analyze involvement of types of β-globin mutations, α-thalassemia, and XmnI-Gγ site in mild clinical symptoms observed in four Thai non-transfusion dependent HbE/βO-thalassemia cases. Materials and methods: EDTA blood samples were collected from the patients and their family members after signing the informed consent. Automated complete blood count with blood smear examination, hemoglobin typing, molecular analysis for α and β-globin mutations, β-globin gene haplotypes, and XmnI-Gγ site were performed on all blood samples. In addition, nucleotide sequencing of β-globin gene and globin chain separation were performed for patient#3 and their parents. Results: The first three patients had hemoglobin levels ranging 8.5-11.2 g/dL, while the fourth patient had hemoglobin level of 6.7 g/dL. The first and fourth patients were compound heterozygote for βE (HBB:c.79G&gt;A) and β17 (HBB:c.52A&gt;T) alleles with typical hemoglobin pattern of EF. The second patient was compound heterozygote for βE and β41/42 (HBB:c.126_129delCTTT) alleles also with typical hemoglobin pattern of EF. The third patient was compound heterozygote of βE and βIVS1-1(HBB:c.92+1G&gt;T), however, with atypical hemoglobin pattern of EE. Family analysis found co-inheritance of Hb Constant Spring (HBA2:c.427T&gt;C) and the XmnI-Gγ site (T at rs7482144) in the first two patients, of SEA-αO thalassemia (NG_000006.1:g.26264_45564del19301) and XmnI-Gγ site in the third patient, and of only XmnI-Gγ site in the fourth patient. Conclusion: These family studies proved the fact that co-existence of SEA-αO thalassemia and Hb Constant Spring in HbE/βO-thalassemia could lead to mild clinical severity. Minimal effect of XmnI-Gγ site on clinical symptoms of this disease was emphasized. This information should be useful in prenatal diagnosis of HbE/β-thalassemia.

Health-Related Quality of Life in FKRP-Related Limb-Girdle Muscular Dystrophy R9.

Limb-girdle muscular dystrophy R9 (LGMDR9) is a chronic progressive hereditary muscle disease, related to the Fukutin Related Protein (FKRP) gene, that may cause major disabilities, cardiomyopathy, and ventilatory failure. Knowledge of how LGMDR9 affects health-related quality of life (HRQoL) is relevant in treatment and care. To investigate HRQoL in the Norwegian LGMDR9 population over 14 months and relation to fatigue and sleep quality. Participants (16+ years) of the Norwegian LGMDR9 cohort study completed two HRQoL measures, i.e., Individualized Neuromuscular Quality of Life questionnaire (INQoL) and the 36-item Short Form (SF-36) at baseline, 8, and 14 months and measures of fatigue and sleep quality at 9 months. HRQoL response rate was 84/90 (75 c.826 C > A homozygotes and nine c.826 C > A compound heterozygotes). Compared to Norwegian normative data, all SF-36 domain scores were impaired (p≤0.006) except mental health in males (p = 0.05) and pain scores. During 14 months, perceived muscle weakness and the INQoL index (disease burden) worsened in c.826 C > A homozygotes. Compound heterozygotes reported more dysphagia and physical difficulties than homozygotes and showed a tendency towards worsening in weakness over time but some improvement on the INQoL index. Homozygous females reported generally poorer HRQoL and a higher burden than males. The INQoL index was related to perceived muscle weakness and fatigue, and fatigue to myalgia and mental distress. The prevalence of fatigue and poor sleep was 40% and 49%, respectively. The 14-month follow-up period shows a worsening of perceived weakness and burden in c.826 C > A homozygotes, which can then be expected. The prevalence and impact of fatigue indicate a need for awareness and treatment of fatigue. Myalgia and mental distress are potential targets in the treatment of fatigue, which future studies need to establish. Sleep issues and gender-specific care needs also require attention in LGMDR9.

Investigation of Recessive Effects of Coding Variants on Common Clinical Phenotypes in Exome-Sequenced UK Biobank Participants

Introduction: Previous studies have demonstrated effects of rare coding variants on common, clinically relevant phenotypes although the additive burden of these variants makes only a small contribution to overall trait variance. Although recessive effects of individual homozygous variants have been studied, little work has been done to elucidate the impact of rare coding variants occurring together as compound heterozygotes. Methods: In this study, attempts were made to identify pairs of variants likely to be occurring as compound heterozygotes using 200,000 exome-sequenced subjects from the UK Biobank. Pairs of variants, which were seen together in the same subject more often than would be expected by chance, were excluded as it was assumed that these might be present in the same haplotype. Attention was restricted to variants with minor allele frequency ≤0.05 and to those predicted to alter amino acid sequence or prevent normal gene expression. For each gene, compound heterozygotes were assigned scores based on the rarity and predicted functional consequences of the constituent variants and the scores were used in a logistic regression analysis to test for association with hypertension, hyperlipidaemia, and type 2 diabetes. Results: No statistically significant associations were observed and the results conformed to the distribution, which would be expected under the null hypothesis. The average number of apparently compound heterozygous subjects for each gene was only 282.2. Conclusion: It seems difficult to detect an effect of compound heterozygotes on the risk of these phenotypes. Even if recessive effects from compound heterozygotes do occur, they would only affect a small number of people and overall would not make a substantial contribution to phenotypic variance. This research has been conducted using the UK Biobank Resource.