Mutations In Autosomal Genes Research Articles

ZNF142 mutation causes sex-dependent neurologic disorder

BackgroundSex-specific predilection in neurological diseases caused by mutations in autosomal genes is a phenomenon whose molecular basis is poorly understood. We studied females of consanguineous Bedouin kindred presenting with severe...

Genetic alterations and molecular mechanisms underlying hereditary intrahepatic cholestasis.

Hereditary cholestatic liver disease caused by a class of autosomal gene mutations results in jaundice, which involves the abnormality of the synthesis, secretion, and other disorders of bile acids metabolism. Due to the existence of a variety of gene mutations, the clinical manifestations of children are also diverse. There is no unified standard for diagnosis and single detection method, which seriously hinders the development of clinical treatment. Therefore, the mutated genes of hereditary intrahepatic cholestasis were systematically described in this review.

Preimplantation genetic diagnosis for a single gene mutation for succinate dehydrogenase subunit B (the genetic basis for malignant paraganglioma) with successful pregnancy

Purpose: To report the first successful case of the birth of normal baby using preimplantation diagnosis for hereditary paraganglioma (PGL) followed by embryo transfer and to emphasize the importance of using mild follicle stimulating hormone (FSH) stimulation for IVF in women with diminished oocyte reserve. Materials and Methods: The female partner had a baseline serum FSH of 16.5 mIU/mL and the male partner had the malignant hereditary form of the PGL - pheochromocytoma (PGL/PCC) syndrome related to a mutation of the nuclear mitochondrial enzyme, succinate-dehydrogenase enzyme (specifically the B subunit) (SDHB). He was suffering from the malignant transformation of these neuroendocrine tumors. Before his death, he wanted to enjoy for a short time a baby with his own genes but feared passing the SDHB autosomal gene mutation to their child. Results: Eight blastomeres from eight embryos biopsied on day 3 were tested for SDHB gene by polymerase chain reaction. These eight metaphase II oocytes were obtained following mild FSH stimulation (150 units from day 3). Intracytoplasmic sperm injection (ICSI) was performed using the frozen/thawed sperm of this 35-year-old male suffering from a malignant pheochromocytoma. Five of the eight embryos were found to have mutations of the SDHB gene. Two embryos with normal SDHB were transferred and one resulted in a healthy baby. Genetic testing of the baby confirmed the absence of the SDHB mutation. Discussion: The successful pregnancy supports, but does not prove, the importance of using mild FSH stimulation in the presence of diminished oocyte reserve to inhibit the iatrogenic development of a much higher percentage of embryos with aneuploidy.

Characterization of patients referred for non-specific intellectual disability testing: the importance of autosomal genes for diagnosis.

Genetic testing for non-specific intellectual disability (ID) presents challenges in daily clinical practice. Historically, the focus of the genetic elucidation of non-specific ID has been on genes on the X chromosome, and recent research has brought attention to the growing contribution of autosomal genes. In addition, next-generation sequencing (NGS) has greatly improved the ability to simultaneously analyze multiple genetic loci, making large panel testing a practical approach to testing for non-specific ID. We performed NGS analysis of a total of 90 genes implicated in non-specific ID. The 90 genes included 56 X-linked genes and 34 autosomal genes. Pathogenic variants were identified in 11 of 52 (21%) patient samples. Nine of the eleven cases harbored mutations in autosomal genes including AP4B1, STXB1, SYNGAP1, TCF4 and UBE3A. Our mutation-positive cases provide further evidence supporting the prevalence of autosomal mutations in patients referred for non-specific ID testing and the utility of their inclusion in multi-gene panel analysis.

Autoinflammatory syndrome

Autoinflammatory syndrome is a group of hereditary, recurrent and non-invasive inflammatory diseases characterized by recurrent fever, arthralgia and rashes without the increase of autoantibodies and reactive T lymphocytes. At present, it is considered that the major cause of these diseases is autosomal gene mutations, which may induce abnormalities in cytokines and inflammatory signals followed by a series of autoinflammatory responses. Although no ideal therapy is available, immunosuppressants and biological agents have shown some efficacy. Key words: Diagnosis; Clinical protocols; Autoinflammatory syndrome

Reduced selection and accumulation of deleterious mutations in genes exclusively expressed in men

Sex-limited selection can moderate the elimination of deleterious mutations from the population and contribute to the high prevalence of common human diseases. Accordingly, deleterious mutations in autosomal genes that are exclusively expressed in only one of the sexes undergo sex-limited selection and can reach higher frequencies than mutations similarly selected in both sexes. Here we show that the number of deleterious SNPs in genes exclusively expressed in men is twofold higher than in genes that are selected in both sexes. Additional analyses suggest that the increased number of damaging mutations we found in male-specific genes is due to reduced selection in females. These results are noteworthy since many of these male-specific genes are known to be crucial for male reproduction, and are thus likely to be under strong purifying selection. We suggest that inheritance of male-infertility-causative mutations through unaffected female lineages contributes to the high incidence of male infertility.

Prevalence of Mutations in eyeGENE Probands With a Diagnosis of Autosomal Dominant Retinitis Pigmentosa

To screen samples from patients with presumed autosomal dominant retinitis pigmentosa (adRP) for mutations in 12 disease genes as a contribution to the research and treatment goals of the National Ophthalmic Disease Genotyping and Phenotyping Network (eyeGENE). DNA samples were obtained from eyeGENE. A total of 170 probands with an intake diagnosis of adRP were tested through enrollment in eyeGENE. The 10 most common genes causing adRP (IMPDH1, KLHL7, NR2E3, PRPF3/RP18, PRPF31/RP11, PRPF8/RP13, PRPH2/RDS, RHO, RP1, and TOPORS) were chosen for PCR-based dideoxy sequencing, along with the two X-linked RP genes, RPGR and RP2. RHO, PRPH2, PRPF31, RPGR, and RP2 were completely sequenced, while only mutation hotspots in the other genes were analyzed. Disease-causing mutations were identified in 52% of the probands. The frequencies of disease-causing mutations in the 12 genes were consistent with previous studies. The Laboratory for Molecular Diagnosis of Inherited Eye Disease at the University of Texas in Houston has thus far received DNA samples from 170 families with a diagnosis of adRP from the eyeGENE Network. Disease-causing mutations in autosomal genes were identified in 48% (81/170) of these families while mutations in X-linked genes accounted for an additional 4% (7/170). Of the 55 distinct mutations detected, 19 (33%) have not been previously reported. All diagnostic results were returned by eyeGENE to participating patients via their referring clinician. These genotyped samples along with their corresponding phenotypic information are also available to researchers who may request access to them for further study of these ophthalmic disorders. (ClinicalTrials.gov number, NCT00378742.).

Heterozygous N-terminal deletion of IκBα results in functional nuclear factor κB haploinsufficiency, ectodermal dysplasia, and immune deficiency

Nuclear factor kappaB (NF-kappaB) is a master transcriptional regulator critical for ectodermal development and normal innate and adaptive immune function. Mutations in the IkappaB kinase gamma/NF-kappaB essential modifier have been described in male subjects with the syndrome of X-linked ectodermal dysplasia with immune deficiency that results from impaired activation of NF-kappaB. We sought to determine the genetic cause of ectodermal dysplasia with immune deficiency in a female patient. Toll-like receptor-induced production of the NF-kappaB-dependent cytokines TNF-alpha and IFN-alpha was examined by means of ELISA, the patient's IkappaBalpha gene was sequenced, and NF-kappaB activation was evaluated by means of electrophoretic mobility shift assay and NF-kappaB-luciferase assays in transfectants. Toll-like receptor function was impaired in the patient. Sequencing of the patient's IkappaBalpha gene revealed a novel heterozygous mutation at amino acid 11 (W11X). The mutant IkappaBalphaW11X protein did not undergo ligand-induced phosphorylation or degradation and retained NF-kappaB in the cytoplasm. This led to roughly a 50% decrease in NF-kappaB DNA-binding activity, leading to functional haploinsufficiency of NF-kappaB activation. Unlike the only other reported IkappaBalpha mutant associated with ectodermal dysplasia associated with immune deficiency (ED-ID), S32I, IkappaBalphaW11X exerted no dominant-negative effect. Functional NF-kappaB haploinsufficiency was associated with ED-ID, and this strongly suggests that normal ectodermal development and immune function are stringently dependent on NF-kappaB in that they might require more than half of normal NF-kappaB activity. Although ED-ID is well described in male subjects, female subjects can present with a similar syndrome of ectodermal dysplasia with immune deficiency resulting from mutations in autosomal genes within the NF-kappaB pathway.

Ability of Abnormally‐Shaped Human Spermatozoa to Adhere to and Penetrate Zona‐Free Hamster Eggs: Correlation With Sperm Morphology and Postincubation Motility

A body of evidence indicates that morphologically abnormal human spermatozoa may exhibit impaired ability to fertilize. Yet teratospermia has widely varying etiologies, including associations with varicoceles, following fever, cigarette smoking, and exposure to polychlorinated biphenyls. Abnormalities of sperm shape in mice have also been shown to be associated with autosomal gene mutations. These varying causes of teratospermia could have different molecular consequences reflected in altered sperm function. We studied the ability of morphologically abnormal human sperm to penetrate zona-free hamster eggs as a measure of their ability to undergo an acrosome reaction and gamete membrane fusion. Motile sperm from ejaculates containing 15% normal sperm or less, as judged by World Health Organization (1999) criteria, were recovered by ISolate density centrifugation and capacitated by overnight incubation. Zona-free hamster eggs were inseminated with 1 x 10(6) motile capacitated cells and scored for sperm penetration after 3 hours of coincubation. A significant trend was found between the percent of abnormal spermatozoa within the ejaculate and impaired egg-penetrating ability, reflected in the percent of eggs penetrated, the number of penetrating sperm per egg, and the number of sperm adherent to the oolemma. Because only acrosome-reacted human spermatozoa adhere to the oolemma, these results support the notion that abnormally shaped sperm may exhibit an impaired ability to undergo an acrosome reaction. A correlation was also noted between the loss of motility of sperm following overnight incubation and impairment of their ability to undergo gamete membrane fusion. These results confirm prior findings at the level of the zona pellucida that abnormally shaped sperm exhibit functional abnormalities. However, a wide variation was observed between men in the behavior of such sperm, including occasionally high rates of egg penetration. These observations suggest that assessment of morphology may be an unreliable measure, for the individual, of sperm fertilizing ability and emphasize that sperm function testing is an important part of the evaluation of teratospermia.

Connexin 26 mutations in autosomal recessive deafness disorders: A review

This review explores the association between GJB2 gene mutations, encoding connexin 26 (Cx26), and nonsyndromic hearing loss. Connexins are proteins that form intracellular membrane channels and regulate ion movement between contiguous fluid spaces. A family of autosomal gene mutations has been identified that lead to abnormal connexin expression within the inner ear that are associated with hearing loss. The exact mechanism by which this link is elicited remains unclear. We aim to highlight the clinically underestimated prevalence of GJB2 gene mutations, to explore the influential role of ethnic diversity in mutation frequency, and to provide a framework for hearing specialists in considering the differential diagnosis of nonsyndromic hearing loss. By linking an observed phenotype associated with abnormal Cx26 expression to the current understanding of the biological and genetic basis underlying it will allow a more accurate clinical description of associated hearing loss, and therefore enable more effective patient management and genetic counselling.

Prevalence of Disease-Causing Mutations in Families with Autosomal Dominant Retinitis Pigmentosa: A Screen of Known Genes in 200 Families

To survey families with clinical evidence of autosomal dominant retinitis pigmentosa (adRP) for mutations in genes known to cause adRP. Two hundred adRP families, drawn from a cohort of more than 400 potential families, were selected by analysis of pedigrees. Minimum criteria for inclusion in the adRP cohort included either evidence of at least three generations of affected individuals or two generations with evidence of male-to-male transmission. Probands from each family were screened for mutations in 13 genes known to cause adRP: CA4, CRX, FSCN2, IMPDH1, NRL, PRPF3 (RP18), PRPF8 (RP13), PRPF31 (RP11), RDS, RHO, ROM1, RP1, and RP9. Families without mutations in autosomal genes and in which an X-linked mode of inheritance could not be excluded were tested for mutations in ORF 15 of X-linked RPGR. Potentially pathogenic variants were evaluated based on a variety of genetic and computational criteria, to confirm or exclude pathogenicity. A total of 82 distinct, rare (nonpolymorphic) variants were detected among the genes tested. Of these, 57 are clearly pathogenic based on multiple criteria, 10 are probably pathogenic, and 15 are probably benign. In the cohort of 200 families, 94 (47%) have one of the clearly pathogenic variants and 10 (5%) have one of the probably pathogenic variants. One family (0.5%) has digenic RDS-ROM1 mutations. Two families (1%) have a pathogenic RPGR mutation, indicating that families with apparent autosomal transmission of RP may actually have X-linked genetic disease. Thus, 107 families (53.5%) have mutations in known genes, leaving 93 whose underlying cause is still unknown. Together, the known adRP genes account for retinal disease in approximately half of the families in this survey, mostly Americans of European origin. Among the adRP genes, IMPDH1, PRPF8, PRPF31, RDS, RHO, and RP1 each accounts for more than 2% of the total; CRX, PRPF3, and RPGR each accounts for roughly 1%. Disease-causing mutations were not found in CA4, FSCN2, NRL, or RP9. Because some mutations are frequent and some regions are more likely to harbor mutations than others, more than two thirds of the detected mutations can be found by screening less than 10% of the total gene sequences. Among the remaining families, mutations may lie in regions of known genes that were not tested, mutations may not be detectable by PCR-based sequencing, or other loci may be involved.

An avian model of genetic reflex epilepsy.

The Fayoumi strain of chickens (Fepi) carries a recessive autosomal gene mutation in which homozygotes are afflicted with a photogenic and audiogenic reflex epilepsy. Seizures consist of stimulus-locked motor symptoms followed by generalized self sustained convulsions. EEG recordings show spikes and spike and waves patterns at rest which are suppressed during seizures and replaced by a desynchronized pattern of activity. Neurones of the prosencephalon discharge in bursts at rest, while neurones of the mesencephalon are bursting during seizures. Living neural chimeras were obtained by replacing specific embryonic brain vesicles in a normal chicken embryo with equivalent vesicles from a Fepi donor. These chimeras show that the epileptic phenotype can be totally or partially transferred from the Fepi to the normal chickens. Total transfer of photogenic and audiogenic seizures was obtained by substitution of both the prosencephalon and mesencephalon, while substitution of the prosencephalon alone resulted in transfer of interictal paroxysmal activity and substitution of the mesencephalon alone resulted principally in transfer of ictal motor symptoms. Increased expression of the c-fos protooncogene, as revealed by the western blot technique, confirmed the distinct encephalic localizations of the symptoms of the photogenic and audiogenic reflex epilepsy of the Fepi shown with the methods of electrophysiology and brain chimeras. We conclude that the Fepi is a good model of brain stem reflex epilepsy and suggest that the brain stem is a generator of some other animal and human genetic reflex "epileptic syndromes".

Potential for the evolution of resistance to pheromone‐based mating disruption tested using two pheromone strains of the cabbage looper, Trichoplusia ni

The reliance of most moth species on female-produced sex pheromones for mate attraction makes their communication system an ideal target for pest management. Mating disruption, by release of synthetic sex pheromone into the atmosphere, has been developed to control many lepidopteran pests and is available commercially for several species (Carde & Minks, 1995). Selection pressure provided by continuous application of mating disruptants could result in the evolution of resistance to this tactic, and this possibility should be evaluated before it occurs. The potential for resistance to mating disruption will depend on genetically-based variation in production of and response to pheromone within and amongst populations (Lofstedt, 1990, 1993; Phelan, 1992). The diverse phylogenetic pattern of lepidopteran pheromones suggests that natural selection has shaped the evolution of species-specific pheromones. Long-term use of mating disruptants that effectively control pest populations, could provide the necessary selection pressure for an alteration in the communication system and the evolution of resistance to mating disruption (Carde & Minks, 1995). In the cabbage looper, Trichoplusia ni (Hubner), the sex pheromone consists of a main component, Z7-dodecenyl acetate (Z7-12:Ac), and five minor components (Bjostad et al., 1984). Haynes & Hunt (1990) discovered an abnormal pheromone phenotype in a laboratory colony of T. ni that was the result of a single, recessive autosomal gene mutation. Mutant females release a pheromone that contains a twenty-fold increase of one minor component, Z9-tetradecenyl acetate (Z9-14:Ac) and a thirty-fold decrease of another minor component, Z5-dodecenyl acetate (Z512:Ac). Initially, male T. ni that carried the mutant gene responded like normal males, demonstrating a preference for the normal pheromone. However, after 49 generations within a pure mutant colony, males responded equally well to both mutant and normal pheromones (Liu & Haynes, 1994). Thus, there are genetically-based differences in both female pheromone and male response (Liu & Haynes, 1994). The potential for mating disruption to result in evolutionary changes in the pheromone was tested on laboratory-derived populations of T. ni using a replicated selection experiment in large field cages. We manipulated the environment (pheromone-treated vs. clean-air control) that moths were exposed to and followed the evolution of the pheromone phenotype in five closed (no gene flow) populations across four offspring generations. The normal pheromone blend applied as a mating disruptant provided selection pressure that influenced the frequency of the mutant allele in the population.

Estimate of severe autosomal recessive limb-girdle muscular dystrophy (LGMD2C, LGMD2D) among sporadic muscular dystrophy males: a study of 415 familes.

Ninety-five percent of cases of severe muscular dystrophy with early childhood onset result from mutations in the dystrophin region of the human X chromosome (DMD, McKusick 310200), whereas 5% are thought to result from mutations in autosomal genes. We examined a total of 415 families with at least one living patient whose clinical features suggested DMD. Based on formal genetics, haplotype analysis, and dystrophin determinations, we estimate that one in eight (11.8%) sporadic male patients carries autosomal rather than X chromosomal mutations.

Impotence induced by a single gene mutation.

Inbred male mice homozygous for the stubby gene mutation were reported to be sterile nineteen years ago. However, the basis of the sterility has not been identified since testicular steroidogenesis and spermatogenesis are normal. In the present studies, the sexual behavior of stubby mice and their coisogenic, normal siblings was compared quantitatively. The experimental observations provided unequivocal evidence that the phenotypic basis of the sterility of stubby mice is impotency. Stubby mice represent the first animal model for the study of impotence and provide the first evidence of an autosomal gene mutation that has a primary effect on male sexual behavior.

Syndromes of thyroid hormone resistance

Resistance to the action of thyroid hormone can involve both peripheral tissues and the pituitary (global resistance), the pituitary only or peripheral tissues alone. Global resistance is of variable severity and has been observed in more than 60 individuals, the majority occurring in 17 families. Affected subjects are commonly eumetabolic and have goiters, elevated plasma levels of total and free thyroxine and triiodothyronine, normal thyroid hormone metabolism, and normal serum TSH levels (albeit high for the corresponding levels of thyroid hormone). A variable degree of delayed bone maturation, mental retardation, learning disabilities, and hearing defects have been reported; and a variety of treatment regimens, most of which are aimed at reducing the level of plasma hormones and/or goiter, have been attempted before the correct diagnosis has been reached. The clinical disorder is equally common in males and females and appears to be due to one or more autosomal gene mutations. The causes for the hormone resistance may be heterogeneous, either influencing the receptor for thyroid hormones or some unidentified steps in hormone action. At present, the diagnosis is one of exclusion; no effective therapy is available, and all measures designed to lower serum thyroid hormone levels should be avoided.

Meiotic studies in mice carrying the sex reversal (Sxr) factor.

A sex reversal factor (Sxr) that causes mice having apparently normal X chromosomes to become phenotypically male is transmitted in an autosomal pattern. The origin of the Sxr factor is still unknown. It seems most likely that it has originated from an autosomal gene mutation or is the result of a translocation of part of the Y chromosome to one of the autosomes. Chromosomes from four XY and six XO mice carrying this sex reversal factor were examined in the diakinesis stage of meiosis. The following unusual observations were noted: (1) in XY males carrying the Sxr factor, the X and Y chromosomes were separated more often than in controls. (2) The Y chromosome tends to be closer to an autosome when the X and Y are separate than when the X and Y are attached. (3) A chromosome fragment was present in 4/226 cells from two XO males and a single cell from an XY, Sxr carrier. Although there is no direct evidence, these observations seem to favor the possibility that the Sxr factor involves a chromosomal rearrangement rather than a single gene mutation.

Induction of paternal sex-chromosome losses and deletions and of autosomal gene mutations by the treatment of mouse post-meiotic germ cells with triethylenemelamine

The treatment of male mouse post-meiotic germ cells with triethylenemelamine was found to induced paternal sex-chromosome loss, aberrations of the paternal X, and also specific-locus autosomal gene mutations. Two spontaneously occurring patroclinous XO females and one XYY male were also detected.

Chromosomes of Normal and Dwarf Cattle

Chromosomes of dwarf female cattle were observed in comparison with those of normal females and males. Normal as well as dwarf female cattle had 60 chromosomes, namely 29 telocentric autosome pairs and one submedian metacentric X pair. There was no difference in thh karyotype between normal and dwarf cattle. Male normal cattle had 29 telocentric autosome pairs and in addition a submedian X and a median metacentric Y chromosome. From the above investigation, it was considered that the character of dwarfism is not reflected in the karyotype being due to a sigle autosomal gene mutation.