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Results for “X-linked inheritance”

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PubMed1975

Leukodystrophy, skin hyperpigmentation, and adrenal atrophy: Siemerling-Creutzfeldt disease. Transmission through several generations in two families.

Two apparently unrelated families with a history of leukodystrophy associated with adrenal insufficiency are presented. Only about 20 cases of this syndrome have been reported until now. It was first described by Siemerling and Creutzfeldt; therefore we propose the designation Siemerling-Creutzfeldt disease. Our pedigrees include 15 additional cases and prove that this disease is inherited as an X-linked or as an autosomal dominant trait with male sex limitation. Within these families, the interindividual variability of clinical signs is remarkable. Patients can survive into the fifth decade, and one has reproduced. Attempts to identify heterozygotes on the basis of endocrinologic investigations were unsuccessful.

Adrenal Cortex Hormones↗
PubMed2026

First Cornelia de Lange Syndrome Type 4 Caused by the Gonadal Mosaicism of RAD21 Deletion.

BACKGROUND: Cornelia de Lange syndrome (CdLS) currently has seven known causative genes, inherited in an autosomal or X-linked dominant pattern. Clinical features are variable, including dysmorphic facial features, intrauterine and/or postnatal growth retardation, multiple organ system malformations, and neurodevelopmental disorders. Type 4 of CdLS caused by RAD21 gene has a relatively mild phenotype. METHODS: Here, we report a pair of siblings from a Chinese family who both have similar dysmorphic facial features, cleft palate, spina bifida occulta, and limb phenotypes. Whole-genome sequencing (WGS) was performed to analyze the genetic basis of their condition. Gap-PCR was subsequently employed to map the breakpoints in the affected siblings' peripheral blood samples. Additionally, the copy number status of the parents and the father's sperm DNA were evaluated using Gap-PCR and digital PCR (dPCR). RESULTS: Through WGS analysis, a heterozygous deletion was found in the 8q23.3-8q24.11 region of both patients, which includes the full-length RAD21 gene. And we mapped the breakpoint with the peripheral blood samples of the affected siblings using Gap-PCR. The parents' peripheral blood had normal copy number. The father's sperm DNA was negative for the deletion by both Gap-PCR and dPCR, whereas the mother's peripheral blood was also negative, suggesting the deletion is likely due to maternal gonadal mosaicism. CONCLUSIONS: We report a pair of siblings with a complete loss of RAD21, with evidence supporting maternal gonadal mosaicism. This information will be helpful for genetic counseling for Type 4 of CdLS.

Humans↗
PubMed2025

Identification of IDH3G, encoding the gamma subunit of mitochondrial isocitrate dehydrogenase, as a novel candidate gene for X-linked retinitis pigmentosa.

PURPOSE: Retinitis pigmentosa (RP) is a genetically heterogeneous group of retinal degenerative disorders characterized by the loss of rod and cone photoreceptors, leading to visual impairment and blindness. To date, to our knowledge, X-linked RP has been associated with variants in 3 genes (RPGR, RP2, and OFD1), whereas genetic defects at 3 loci (RP6, RP24, and RP34) are yet unidentified. The aim of this study was to identify a novel candidate gene underlying X-linked RP. METHODS: Participants were identified from cohorts of genetically unsolved male individuals affected by RP, who underwent genome sequencing, exome sequencing, or candidate gene screening via direct Sanger sequencing at 3 referral centers. Specifically, 2 probands were identified at the National Reference Centre for Rare Retinal Diseases (Paris, France), 2 at the Massachusetts Eye and Ear Hospital (Boston, MA), and 1 at the National Reference Centre for Inherited Sensory Diseases (Montpellier, France). The pathogenicity of the identified variants was assessed using bioinformatic predictions, protein expression analyses, and mitochondrial function assays. RESULTS: We identified 4 rare single-nucleotide variants in IDH3G (HGNC:5386), located at the RP34 locus on the X chromosome, and a complete gene deletion, in 5 unrelated male individuals affected with nonsyndromic RP. The variants segregated with the phenotype in all available family members. In all cases, the disease severity was intermediate. None had high myopia. IDH3G encodes the γ subunit of mitochondrial isocitrate dehydrogenase (IDH3), an enzyme involved in the citric acid cycle, which is expressed in the inner segments of photoreceptors. Variants in IDH3A and IDH3B, encoding the other subunits of IDH3, have already been associated with nonsyndromic autosomal recessive RP. Bioinformatic predictions and functional assays support a pathogenic role for the variants identified in this study, possibly through partial loss of enzymatic activity and mitochondrial function. CONCLUSION: Our findings suggest that variants in IDH3G are a novel cause of X-linked RP.

Humans↗
PubMed1979

Fabry's disease in a black kindred.

In a 16-member black kindred with Fabry's disease, four hemizygous males had plasma alpha-galactosidase levels less than 6% and seven heterozygous females had plasma alpha-galactosidase levels between 10% and 50% of normal. A 16-year-old index male had hypertension with left ventricular hypertrophy, abnormal renal function, tortuous retinal veins, "myelin" inclusions in bone marrow macrophages, and intraepithelial inclusion bodies in the kidney. Scrotal angiectasia developed a year after diagnosis. The three other affected males had left ventricular hypertrophy and retinal vein tortuosity. Of the seven carrier females, five had frequent headaches, four had retinal vessel changes, three had proteinuria with normal renal function, and two had bundle-branch blocks on ECGs. There was no deuteranomalopia in this family, although the inheritance pattern of the Fabry gene is X-linked recessive.

Adolescent↗
PubMed2024

Exome sequencing reveals neurodevelopmental genes in simplex consanguineous Iranian families with syndromic autism.

BACKGROUND AND OBJECTIVE: Autosomal recessive genetic disorders pose significant health challenges in regions where consanguineous marriages are prevalent. The utilization of exome sequencing as a frequently employed methodology has enabled a clear delineation of diagnostic efficacy and mode of inheritance within multiplex consanguineous families. However, these aspects remain less elucidated within simplex families. METHODS: In this study involving 12 unrelated simplex Iranian families presenting syndromic autism, we conducted singleton exome sequencing. The identified genetic variants were validated using Sanger sequencing, and for the missense variants in FOXG1 and DMD, 3D protein structure modeling was carried out to substantiate their pathogenicity. To examine the expression patterns of the candidate genes in the fetal brain, adult brain, and muscle, RT-qPCR was employed. RESULTS: In four families, we detected an autosomal dominant gene (FOXG1), an autosomal recessive gene (CHKB), and two X-linked autism genes (IQSEC2 and DMD), indicating diverse inheritance patterns. In the remaining eight families, we were unable to identify any disease-associated genes. As a result, our variant detection rate stood at 33.3% (4/12), surpassing rates reported in similar studies of smaller cohorts. Among the four newly identified coding variants, three are de novo (heterozygous variant p.Trp546Ter in IQSEC2, heterozygous variant p.Ala188Glu in FOXG1, and hemizygous variant p.Leu211Met in DMD), while the homozygous variant p.Glu128Ter in CHKB was inherited from both healthy heterozygous parents. 3D protein structure modeling was carried out for the missense variants in FOXG1 and DMD, which predicted steric hindrance and spatial inhibition, respectively, supporting the pathogenicity of these human mutants. Additionally, the nonsense variant in CHKB is anticipated to influence its dimerization - crucial for choline kinase function - and the nonsense variant in IQSEC2 is predicted to eliminate three functional domains. Consequently, these distinct variants found in four unrelated individuals with autism are likely indicative of loss-of-function mutations. CONCLUSIONS: In our two syndromic autism families, we discovered variants in two muscular dystrophy genes, DMD and CHKB. Given that DMD and CHKB are recognized for their participation in the non-cognitive manifestations of muscular dystrophy, it indicates that some genes transcend the boundary of apparently unrelated clinical categories, thereby establishing a novel connection between ASD and muscular dystrophy. Our findings also shed light on the complex inheritance patterns observed in Iranian consanguineous simplex families and emphasize the connection between autism spectrum disorder and muscular dystrophy. This underscores a likely genetic convergence between neurodevelopmental and neuromuscular disorders.

Humans↗
PubMed1975

Mutant feedback-resistant phosphoribosylpyrophosphate synthetase associated with purine overproduction and gout. Phosphoribosylpyrophosphate and purine metabolism in cultured fibroblasts.

We have reported previously two siblings with gout and uric acid lithiasis associated with excessive purine production. In the erythrocytes of these patients, phosphoribosylpyrophosphate (PRPP) synthetase exhibited resistance to feedback-inhibition by normal cell constituents such as guanosine-5'-diphosphate (GDP) and adenosine-5'-diphosphate (ADP), resulting in superactivity of the mutant enzyme and consequently in increased PRPP content and availability for nucleotide synthesis. Erythrocyte PRPP content and availability were normal in the propositus' parents, his healthy brother and three sons, and they all had normal serum level and urinary excretion of uric acid, except for the mother who was hyperuricosuric. To further characterize this mutation we studied PRPP and purine metabolism in cultured fibroblasts of the affected family. PRPP synthetase in dialyzed lysates of fibroblasts from the propositus and his mother exhibited increased specific activity, more markedly at low inorganic phosphate concentration, and decreased sensitivity to inhibition by ADP and GDP, PRPP content and availability and the rate of de novo purine nucleotide synthesis were markedly increased in the fibroblasts of the propositus and to a lesser extent in the fibroblasts of his mother but were normal in the fibroblasts of the other family members investigated. The fibroblast studies demonstrate the following sequence of abnormalities: feedback-resistance of PRPP synthetase; superactivity of this enzyme in normal physiological milieu; increased availability of PRPP; and increased de novo synthesis of purine nucleotides. The pattern of inheritance of this disorder is compatible with both an X-linked recessive and autosomal dominant traits.

Adolescent↗
PubMed1977

The deficiency of a lysosomal acid hydrolase in two clones derived from the human lymphoblastoid line F137 after mutagen treatment.

Two clones (out of a total of 181 clones tested) derived from the human lymphoblastoid (lymphoid) line F137 after mutagen treatment were found to be deficient in a lysosomal acid hydrolase. The clone N32 derived from EMS-treated F137 is deficient in N-acetyl hexosaminidase A and B but contains normal levels of N-acetyl hexosaminidase C and low levels of an enzyme resembling N-acetyl hexosaminidase S. Thus the enzyme deficiency in this clone appears to resemble the so-called Sandhoff variant of Tay-Sachs disease, a disease inherited as an autosomal recessive condition. The clone G3 derived from MNNG treated F137 is deficient in alpha-galactosidase A. This clone resembles the situation in X-linked Fabry's disease. Karyotype analysis of the clones failed to reveal any chromosome rearrangement or losses of chromosomal material that might have accounted for the mutations and it is suggested that a single point mutation might in each case account for the loss of enzyme activity. No storage of the natural substrates of the two enzymes could be demonstrated in the clones.

Cell Line↗
PubMed1979

Enzyme histochemistry of the small intestine in inherited ichthyosis.

Enzyme histochemistry of biopsies from the small intestine of 5 patients with different forms of inherited ichthyosis and of 2 normal volunteers was performed. Two of the patients had ichthyosis vulgaris, two had non-bullous congenital ichthyosiform erythroderma and one had X-linked ichthyosis. The following enzymatic activities were examined: G6P-D, 6PG-D, NADPH2-TR, ALD-A, L-D, C-A, IC-D, S-D, M-D, NADH2-TR, ATP-AI, ATP-A II, ATP-A III, ATP-A IV, R5P-A, DHO-D, alphaGP-D, betaHOB-D, MAO, GL-D alphaGP-A I, alphaGP-A II, betaGP-A II, N.EST-A. No significant variations in the different enzymatic activities were found for the ichthyosis vulgaris and non-bullous C.I.E. cases. More pronounced variations were found in X-linked ichthyosis, with a decrease in C-A, IC-D, R5P-A, betaHOB-D, GL-D, alphaGP-A II and N.EST-A activity. Succinic dehydrogenase activity has been reported in the literature to be reduced in ichthyosis vulgaris and bullous C.I.E. However, the results obtained for our patients showed equal or higher reaction levels than in the controls.

Histocytochemistry↗
PubMed1976

Pathogenesis and phenotypes of an X-linked recessive lymphoproliferative syndrome.

A new X-linked recessive lymphoproliferative syndrome has variable phenotypes: fatal infectious mononucleosis (I.M.), agammaglobulinaemia after I.M., American Burkitt's lymphoma, histiocytic lymphoma, immunoblastic sarcoma of B cells, or plasmacytoma. An immunodeficiency to rubeola and the Epstein-Barr virus probably ensues from the mutant gene. The phenotypes (spectrum of B-cell disorders) have a common inheritance and the aetiology is similar.

Adolescent↗
PubMed2015

Perspective on Adeno-Associated Virus Capsid Modification for Duchenne Muscular Dystrophy Gene Therapy.

Duchenne muscular dystrophy (DMD) is a X-linked, progressive childhood myopathy caused by mutations in the dystrophin gene, one of the largest genes in the genome. It is characterized by skeletal and cardiac muscle degeneration and dysfunction leading to cardiac and/or respiratory failure. Adeno-associated virus (AAV) is a highly promising gene therapy vector. AAV gene therapy has resulted in unprecedented clinical success for treating several inherited diseases. However, AAV gene therapy for DMD remains a significant challenge. Hurdles for AAV-mediated DMD gene therapy include the difficulty to package the full-length dystrophin coding sequence in an AAV vector, the necessity for whole-body gene delivery, the immune response to dystrophin and AAV capsid, and the species-specific barriers to translate from animal models to human patients. Capsid engineering aims at improving viral vector properties by rational design and/or forced evolution. In this review, we discuss how to use the state-of-the-art AAV capsid engineering technologies to overcome hurdles in AAV-based DMD gene therapy.

Animals↗
PubMed2021

Early-Onset Atrial Fibrillation and the Prevalence of Rare Variants in Cardiomyopathy and Arrhythmia Genes.

IMPORTANCE: Early-onset atrial fibrillation (AF) can be the initial manifestation of a more serious underlying inherited cardiomyopathy or arrhythmia syndrome. OBJECTIVE: To examine the results of genetic testing for early-onset AF. DESIGN, SETTING, AND PARTICIPANTS: This prospective, observational cohort study enrolled participants from an academic medical center who had AF diagnosed before 66 years of age and underwent whole genome sequencing through the National Heart, Lung, and Blood Institute's Trans-Omics for Precision Medicine program. Participants were enrolled from November 23, 1999, to June 2, 2015. Data analysis was performed from October 24, 2020, to March 11, 2021. EXPOSURES: Rare variants identified in a panel of 145 genes that are included on cardiomyopathy and arrhythmia panels used by commercial clinical genetic testing laboratories. MAIN OUTCOMES AND MEASURES: Sequencing data were analyzed using an automated process followed by manual review by a panel of independent, blinded reviewers. The primary outcome was classification of rare variants using American College of Medical Genetics and Genomics criteria: benign, likely benign, variant of undetermined significance, likely pathogenic, or pathogenic. Disease-associated variants were defined as pathogenic/likely pathogenic variants in genes associated with autosomal dominant or X-linked dominant disorders. RESULTS: Among 1293 participants (934 [72.2%] male; median [interquartile range] age at enrollment, 56 [48-61] years; median [interquartile range] age at AF diagnosis, 50 [41-56] years), genetic testing identified 131 participants (10.1%) with a disease-associated variant, 812 (62.8%) with a variant of undetermined significance, 92 (7.1%) as heterozygous carriers for an autosomal recessive disorder, and 258 (20.0%) with no suspicious variant. The likelihood of a disease-associated variant was highest in participants with AF diagnosed before the age of 30 years (20 of 119 [16.8%; 95% CI, 10.0%-23.6%]) and lowest after the age of 60 years (8 of 112 [7.1%; 95% CI, 2.4%-11.9%]). Disease-associated variants were more often associated with inherited cardiomyopathy syndromes compared with inherited arrhythmias. The most common genes were TTN (n = 38), MYH7 (n = 18), MYH6 (n = 10), LMNA (n = 9), and KCNQ1 (n = 8). CONCLUSIONS AND RELEVANCE: In this cohort study, genetic testing identified a disease-associated variant in 10% of patients with early-onset AF (the percentage was higher if diagnosed before the age of 30 years and lower if diagnosed after the age of 60 years). Most pathogenic/likely pathogenic variants are in genes associated with cardiomyopathy. These results support the use of genetic testing in early-onset AF.

Adult↗
PubMed2025

Identification of a novel non-coding deletion in Allan-Herndon-Dudley syndrome by long-read HiFi genome sequencing.

BACKGROUND: Allan-Herndon-Dudley syndrome (AHDS) is an X-linked disorder caused by pathogenic variants in the SLC16A2 gene. Although most reported variants are found in protein-coding regions or adjacent junctions, structural variations (SVs) within non-coding regions have not been previously reported. METHODS: We investigated two male siblings with severe neurodevelopmental disorders and spasticity, who had remained undiagnosed for over a decade and were negative from exome sequencing, utilizing long-read HiFi genome sequencing. We conducted a comprehensive analysis including short-tandem repeats (STRs) and SVs to identify the genetic cause in this familial case. RESULTS: While coding variant and STR analyses yielded negative results, SV analysis revealed a novel hemizygous deletion in intron 1 of the SLC16A2 gene (chrX:74,460,691 - 74,463,566; 2,876 bp), inherited from their carrier mother and shared by the siblings. Determination of the breakpoints indicates that the deletion probably resulted from Alu/Alu-mediated rearrangements between homologous AluY pairs. The deleted region is predicted to include multiple transcription factor binding sites, such as Stat2, Zic1, Zic2, and FOXD3, which are crucial for the neurodevelopmental process, as well as a regulatory element including an eQTL (rs1263181) that is implicated in the tissue-specific regulation of SLC16A2 expression, notably in skeletal muscle and thyroid tissues. CONCLUSIONS: This report, to our knowledge, is the first to describe a non-coding deletion associated with AHDS, demonstrating the potential utility of long-read sequencing for undiagnosed patients. Although interpreting variants in non-coding regions remains challenging, our study highlights this region as a high priority for future investigation and functional studies.

Humans↗
PubMed2026

35 Individuals With HUWE1-Related Neurodevelopmental Disorder and Suggested Clinical Evaluations.

HUWE1 (HECT, UBA, and WWE Domain Containing E3 Ubiquitin Protein Ligase1, OMIM 300697), located at Xp11.22, encodes a ubiquitin ligase that is highly conserved across species. Genetic variants in HUWE1 described in multiple independent studies cause X-linked intellectual disability, including in the patients identified by Juberg, Marsidi, and Brooks. This report describes 35 additional cases of individuals with variants in HUWE1 and suggested guidelines for clinical management. Our study includes several female cases, which have not been widely reported previously. Our findings confirm earlier reported clinical features including developmental delay, autism, hypotonia, short stature, and dysmorphic facial features as well as additional multisystemic findings. Intrauterine growth restriction (IUGR) and feeding difficulties were common in the neonatal period. It is notable that nearly all females had de novo variants, and males had de novo or inherited variants from clinically unaffected carrier mothers. Three genetic hotspots were identified in evolutionarily conserved regions of HUWE1 that have clinical impact. This report provides additional characterization of the spectrum of HUWE1-related neurodevelopmental disorder (HNDD).

Humans↗
PubMed2024

Identifying inversions with breakpoints in the Dystrophin gene through long-read sequencing: report of two cases.

BACKGROUND: Duchenne Muscular Dystrophy (DMD) is an X-linked disorder caused by mutations in the DMD gene, with large deletions being the most common type of mutation. Inversions involving the DMD gene are a less frequent cause of the disorder, largely because they often evade detection by standard diagnostic methods such as multiplex ligation probe amplification (MLPA) and whole exome sequencing (WES). CASE PRESENTATION: Our research identified two intrachromosomal inversions involving the dystrophin gene in two unrelated families through Long-read sequencing (LRS). These variants were subsequently confirmed via Sanger sequencing. The first case involved a pericentric inversion extending from DMD intron 47 to Xq27.3. The second case featured a paracentric inversion between DMD intron 42 and Xp21.1, inherited from the mother. In both cases, simple repeat sequences (SRS) were present at the breakpoints of these inversions. CONCLUSIONS: Our findings demonstrate that LRS is an effective tool for detecting atypical mutations. The identification of SRS at the breakpoints in DMD patients enhances our understanding of the mechanisms underlying structural variations, thereby facilitating the exploration of potential treatments.

Humans↗
PubMed2026

EGFLAM Pathogenic Variants and Congenital Stationary Night Blindness.

IMPORTANCE: Congenital stationary night blindness (CSNB) is a clinically and genetically heterogeneous inherited retinal disorder (IRD), and in many complete CSNB (cCSNB) cases, the underlying genetic cause remains unknown. Uncovering the genetic defects of IRDs helps to refine diagnostic methods and supports the development of specific therapeutic approaches. OBJECTIVE: To describe the phenotype and the underlying gene defect in patients with cCSNB from 2 unrelated families. DESIGN, SETTING AND PARTICIPANTS: This retrospective case series was conducted from January 2023 to July 2025. Data for 3 patients from cohorts of genetically unsolved IRD cases in France (n = 140 for CSNB) and the Netherlands (n = 2730 for IRD) were analyzed clinically and genetically. EXPOSURES: Complete ocular examination, including multimodal retinal imaging and full-field electroretinography (ffERG) incorporating the International Society for Clinical Electrophysiology of Vision standards and multimodal retinal imaging, were performed. Gene defects were identified by genome sequencing (GS) and exome sequencing (ES). MAIN OUTCOMES AND MEASURES: The main outcome was a gene defect, EGFLAM, underlying cCSNB. Measures included phenotyping, GS, ES, Sanger sequencing, and cosegregation analysis. RESULTS: The series included 3 patients from 2 unrelated families of Moroccan ancestry showing high myopia, reduced visual acuity, and night blindness. Retinal imaging depicted myopic changes. ffERG revealed electronegative Schubert-Bornschein configuration in keeping with cCSNB with ON-bipolar cell dysfunction. Patients were lacking pathogenic variants in known genes implicated in IRDs, including CSNB. Two different homozygous pathogenic variants, c.1563_1566del, p.(Val522Glufs*18) and c.1795C>T, p.(Arg599*) in EGFLAM were identified by ES and GS. The corresponding protein is localized in the outer plexiform layer and important for ON-bipolar cell signaling in the retina. CONCLUSION AND RELEVANCE: This case series reports on a gene defect in EGFLAM implicated in human cCSNB. Clinicians should be aware about this association and consider including EGFLAM in diagnostic gene panels for IRDs. This discovery may lead to faster and more accurate diagnosis of cCSNB and genetic counseling, as well as a pathway for developing therapies.

Adolescent↗
PubMed1975

X-linked recessive progressive combined variable immunodeficiency (Duncan's disease).

Of 18 boys in Duncan kindred, 6 died of a lymphoproliferative disease. They exhibited a subtle, progressive combined variable immunodeficiency disease characterised by benign or malignant proliferation of lymphocytes, histiocytosis, and alterations in concentrations of serum-immunoglobulins. Infectious mononucleosis occurred during or preceding terminal events in at least 3 of the cousins. Fever, pharyngitis, lymphadenomegaly, hepatosplenomegaly, atypical lymphocytosis, and a spectrum ranging from agammaglobulinaemia to polyclonal hyper-gammaglobulinaemia occurred. At necropsy, the thymus gland and thymic-dependent areas in the lymph-nodes and spleen were depleted of lymphocytes. Diffuse infiltrates composed of lymphocytes, plasma cells, and histiocytes, some containing erythrocytes, invaded the haematopoietic organs, viscera, and central nervous system. In addition, 2 half-brothers had lymphomas of the ileum and central nervous system. Approximately half the boys, including the half-brothers, were affected, and girls were spared, implying sex-linked recessive inheritance. Various lymphohistiocytoses resemble Duncan's disease, but it is distinctive from them in the mode of inheritance or by histiological characteristics. This study suggests that the Epstein-Barr virus or other viruses triggered the fatal proliferation of lymphocytes and that progressive attrition of T-cell functions allowed uncontrolled lymphoproliferation.

Adult↗
PubMed2026

LINE-1 repeats are a defining feature of the Xce.

During early development, female mammals inactivate one X chromosome to balance their X-linked gene dosage with males. While allelic choice is random in inbred mouse populations, choice can be significantly skewed in interstrain hybrids. The genetic basis of skewing has long been attributed to the mysterious "X chromosome controlling element(s)" (Xce) with different strengths among species, subspecies, and strains. When two X-chromosomes with different Xce strengths are inherited by offspring, the X chromosome with the stronger Xce will have a higher probability of remaining active. Here, we provide evidence that L1Tf repeats-a subfamily of long interspersed nuclear elements 1-plays a role in determining Xce strength. L1Tf elements form a condensed core within the inactive X (Xi) territory. Mouse strains with varying Xce strengths differ in the L1Tf copy number on the X chromosome, with the strength of the Xce allele being inversely related to L1Tf copy number. L1Tf expression mediates the Xce effect. However, in contrast to a prior report, L1Tf RNA does not coat the Xi. Rather, L1Tf promotes condensation of the Xi core. Intriguingly, L1Tfs recruit and sequester YY1 from active genes, accelerating XCI in cis. Thus, L1Tf copy number, expression, and binding of YY1 are key defining features of the Xce. We propose a model in which the Xce influences the choice of Xist alleles by promoting YY1 binding to the nucleation site for the initiation of Xist spreading.

Animals↗
PubMed1978

X-linked and autosomal genes controlling mouse alpha-galactosidase expression.

Analysis of F2 and backcross animals has confirmed the X-chromosome linkage of Ags, the structural locus for mouse alpha-galactosidase. The position of Ags has been located in the X chromosome, 9 centimorgans from Mo, and the gene order is centromere-Hq-Bn-Ta-Mo-Ags. A variation in the developmental expression of alpha-galactosidase activity, inherited as an autosomal trait, has been characterized using recombinant inbred lines of mice. Among certain recombinant inbred lines, the variation appears to segregate as a single major locus.

Animals↗