FLNC gene encodes for Filamin-C (FLNC) protein, a sacromeric protein with important structural and signaling functions in the myocyte. Pathogenic dominant variants in FLNC were initially linked to ...myofibrillar myopathy and over time, evidence showed association of this gene with different forms of autosomal dominant cardiomyopathy including hypertrophic, dilated and restrictive forms.
Recently, two cases of recessive FLNC mutations have been reported by Reinstein et al. and Kölbel et al., one with only cardiomyopathy and other with only myopathy.
In this report, we describe a third case, a boy who was diagnosed at 10 years of age with shortness of breath and dilated cardiomyopathy who on sequencing was found to have a novel homozygous splice site variant (NM_001458.4 c.2122-1G>C) in FLNC. This case suggests that the phenotype associated with variants in FLNC is very heterogenous and can be inherited in dominant or recessive forms, with later being more severe and of earlier onset.
Establishing links between Mendelian phenotypes and genes enables the proper interpretation of variants therein. Autozygome, a rich source of homozygous variants, has been successfully utilized for ...the high throughput identification of novel autosomal recessive disease genes. Here, we highlight the utility of the autozygome for the high throughput confirmation of previously published tentative links to diseases.
Autozygome and exome analysis of patients with suspected Mendelian phenotypes. All variants were classified according to the American College of Medical Genetics and Genomics guidelines.
We highlight 30 published candidate genes (ACTL6B, ADAM22, AGTPBP1, APC, C12orf4, C3orf17 (NEPRO), CENPF, CNPY3, COL27A1, DMBX1, FUT8, GOLGA2, KIAA0556, LENG8, MCIDAS, MTMR9, MYH11, QRSL1, RUBCN, SLC25A42, SLC9A1, TBXT, TFG, THUMPD1, TRAF3IP2, UFC1, UFM1, WDR81, XRCC2, ZAK) in which we identified homozygous likely deleterious variants in patients with compatible phenotypes. We also identified homozygous likely deleterious variants in 18 published candidate genes (ABCA2, ARL6IP1, ATP8A2, CDK9, CNKSR1, DGAT1, DMXL2, GEMIN4, HCN2, HCRT, MYO9A, PARS2, PLOD3, PREPL, SCLT1, STX3, TXNRD2, WIPI2) although the associated phenotypes are sufficiently different from the original reports that they represent phenotypic expansion or potentially distinct allelic disorders.
Our results should facilitate the timely relabeling of these candidate disease genes in relevant databases to improve the yield of clinical genomic sequencing.
Primary mitochondrial diseases are a group of genetically and clinically heterogeneous disorders resulting from oxidative phosphorylation (OXPHOS) defects. COX11 encodes a copper chaperone that ...participates in the assembly of complex IV and has not been previously linked to human disease. In a previous study, we identified that COX11 knockdown decreased cellular adenosine triphosphate (ATP) derived from respiration, and that ATP levels could be restored with coenzyme Q10 (CoQ10) supplementation. This finding is surprising since COX11 has no known role in CoQ10 biosynthesis. Here, we report a novel gene‐disease association by identifying biallelic pathogenic variants in COX11 associated with infantile‐onset mitochondrial encephalopathies in two unrelated families using trio genome and exome sequencing. Functional studies showed that mutant COX11 fibroblasts had decreased ATP levels which could be rescued by CoQ10. These results not only suggest that COX11 variants cause defects in energy production but reveal a potential metabolic therapeutic strategy for patients with COX11 variants.
Interleukin 12 receptor beta 1 (IL12Rβ1) deficiency is the most common cause of Mendelian susceptibility to mycobacterial disease (MSMD). MSMD usually predisposes the affected individuals to ...infections with weakly virulent mycobacteria such as Bacille Calmette-Guérin (BCG), environmental mycobacteria, non-typhoidal Salmonella, and certain other intracellular pathogens. MSMD usually presents with disseminated BCG infection after exposure to the BCG vaccine. Infections with non-typhoidal Salmonella are considered the second most common manifestation of MSMD; however, severe presentation with such organisms is unusual. In this report, we describe a case of a previously healthy infant who was found to have IL12Rβ1 deficiency after she presented with hemophagocytic lymphohistiocytosis (HLH) secondary to severe Salmonella enterica sepsis.This case report highlights the importance of considering the diagnosis of MSMD in any patient presenting with severe non-typhoidal Salmonella infections even in the absence of any exposure to low-virulent mycobacteria.
Leukocyte adhesion deficiency-III (LAD-III) is a rare recessive autosomal disorder characterized by bleeding syndrome of Glanzmann-type and life-threatening infections. The main etiology of this ...condition is variations in the
gene, which encodes kindlin-3, an integrin-binding protein. This protein is responsible for the activation of fibrinogen receptors and integrin-mediated hematopoietic cell adhesion. So far, only limited cases of LAD-III have been reported. This case report discusses a two-year-old male infant from the Asir region, Saudi Arabia, who was referred to the pediatric hematology service due to recurrent ecchymosis and epistaxis. He was born at full term with a history of transient tachypnea of the newborn and recurrent bronchiolitis. The patient exhibited normal platelet count and coagulation profiles alongside a familial history of bleeding disorders, including a cousin with a similar condition. The patient also presented with hypospadias and café-au-lait spots. Laboratory findings revealed anemia, microcytosis, and hypochromia indicative of iron deficiency anemia. Whole exome sequencing (WES) identified a homozygous variant of uncertain significance in the
gene, associated with autosomal recessive LAD-III. The patient was subsequently referred to an immunology subspecialty for further investigation and bone marrow transplant preparation. This case underscores the importance of comprehensive clinical and genetic evaluations in pediatric patients with unexplained bleeding tendencies.
Factor X (FX) deficiency is an extremely rare autosomal recessive inherited coagulation defect. We report a case of congenital Factor X-Riyadh deficiency discovered during a routine workup before a ...dental procedure. During routine work-up for dental surgery, prothrombin time (PT) and the international normalized ratio (INR) were prolonged. The prothrombin time (PT) was found to be 78.4 (normal 11-14 seconds) with an international normalized ratio (INR) of 7.83; the activated partial thromboplastin time (APTT) was 30.7 (normal 25-42 seconds). Specific coagulation factor assays confirmed an FX deficiency (<10 % of normal activity) and a mild factor VII deficiency 37% (normal 48%-124%). Molecular genetic analysis of the whole exome sequence (WES) confirmed the diagnosis of FX deficiency (homozygous pathogenic variant c. 271G>A p {Glu91Lys} chr13:113793685). The patient is currently on regular follow-up and is advised to take oral antifibrinolytic medications for any superficial or mucosal bleeding.
Abstract Epileptic encephalopathy with continuous spike-and-wave during sleep is a rare age-related childhood encephalopathy characterized by neuropsychological and motor impairment, epilepsy, and ...typical EEG findings. Fixation-off sensitivity denotes forms of epilepsy and/or EEG abnormalities that occur during eye closure. The authors describe a girl with developmental regression, electrical status epilepticus during sleep (documented by video/EEG recording), and intermittent myoclonus. Her younger brother was diagnosed with atypical benign partial epilepsy, and his repeated video/EEG recordings unexpectedly showed fixation-off sensitivity.
Congenital microcephaly (CM) is an important birth defect with long term neurological sequelae. We aimed to perform detailed phenotypic and genomic analysis of patients with Mendelian forms of CM.
...Clinical phenotyping, targeted or exome sequencing, and autozygome analysis.
We describe 150 patients (104 families) with 56 Mendelian forms of CM. Our data show little overlap with the genetic causes of postnatal microcephaly. We also show that a broad definition of primary microcephaly -as an autosomal recessive form of nonsyndromic CM with severe postnatal deceleration of occipitofrontal circumference-is highly sensitive but has a limited specificity. In addition, we expand the overlap between primary microcephaly and microcephalic primordial dwarfism both clinically (short stature in >52% of patients with primary microcephaly) and molecularly (e.g., we report the first instance of CEP135-related microcephalic primordial dwarfism). We expand the allelic and locus heterogeneity of CM by reporting 37 novel likely disease-causing variants in 27 disease genes, confirming the candidacy of ANKLE2, YARS, FRMD4A, and THG1L, and proposing the candidacy of BPTF, MAP1B, CCNH, and PPFIBP1.
Our study refines the phenotype of CM, expands its genetics heterogeneity, and informs the workup of children born with this developmental brain defect.
FLNC gene encodes for Filamin-C (FLNC) protein, a sacromeric protein with important structural and signaling functions in the myocyte. Pathogenic dominant variants in FLNC were initially linked to ...myofibrillar myopathy and over time, evidence showed association of this gene with different forms of autosomal dominant cardiomyopathy including hypertrophic, dilated and restrictive forms. Recently, two cases of recessive FLNC mutations have been reported by Reinstein et al. and Kölbel et al., one with only cardiomyopathy and other with only myopathy. In this report, we describe a third case, a boy who was diagnosed at 10 years of age with shortness of breath and dilated cardiomyopathy who on sequencing was found to have a novel homozygous splice site variant (NM_001458.4 c.2122-1G>C) in FLNC. This case suggests that the phenotype associated with variants in FLNC is very heterogenous and can be inherited in dominant or recessive forms, with later being more severe and of earlier onset.
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