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Orphanet Journal of Rare Diseases Dec 2007Deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT) activity is an inborn error of purine metabolism associated with uric acid overproduction and a... (Review)
Review
Deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT) activity is an inborn error of purine metabolism associated with uric acid overproduction and a continuum spectrum of neurological manifestations depending on the degree of the enzymatic deficiency. The prevalence is estimated at 1/380,000 live births in Canada, and 1/235,000 live births in Spain. Uric acid overproduction is present inall HPRT-deficient patients and is associated with lithiasis and gout. Neurological manifestations include severe action dystonia, choreoathetosis, ballismus, cognitive and attention deficit, and self-injurious behaviour. The most severe forms are known as Lesch-Nyhan syndrome (patients are normal at birth and diagnosis can be accomplished when psychomotor delay becomes apparent). Partial HPRT-deficient patients present these symptoms with a different intensity, and in the least severe forms symptoms may be unapparent. Megaloblastic anaemia is also associated with the disease. Inheritance of HPRT deficiency is X-linked recessive, thus males are generally affected and heterozygous female are carriers (usually asymptomatic). Human HPRT is encoded by a single structural gene on the long arm of the X chromosome at Xq26. To date, more than 300 disease-associated mutations in the HPRT1 gene have been identified. The diagnosis is based on clinical and biochemical findings (hyperuricemia and hyperuricosuria associated with psychomotor delay), and enzymatic (HPRT activity determination in haemolysate, intact erythrocytes or fibroblasts) and molecular tests. Molecular diagnosis allows faster and more accurate carrier and prenatal diagnosis. Prenatal diagnosis can be performed with amniotic cells obtained by amniocentesis at about 15-18 weeks' gestation, or chorionic villus cells obtained at about 10-12 weeks' gestation. Uric acid overproduction can be managed by allopurinol treatment. Doses must be carefully adjusted to avoid xanthine lithiasis. The lack of precise understanding of the neurological dysfunction has precluded development of useful therapies. Spasticity, when present, and dystonia can be managed with benzodiazepines and gamma-aminobutyric acid inhibitors such as baclofen. Physical rehabilitation, including management of dysarthria and dysphagia, special devices to enable hand control, appropriate walking aids, and a programme of posture management to prevent deformities are recommended. Self-injurious behaviour must be managed by a combination of physical restraints, behavioural and pharmaceutical treatments.
Topics: Genetic Counseling; Humans; Hyperuricemia; Hypoxanthine Phosphoribosyltransferase; Lesch-Nyhan Syndrome; Male; Mutation; Purines; Severity of Illness Index
PubMed: 18067674
DOI: 10.1186/1750-1172-2-48 -
Scientific Reports Mar 2019Spinobulbar muscular atrophy (SBMA) is caused by a trinucleotide repeat expansion in the androgen receptor gene on the X chromosome. There is a toxic effect of the...
Spinobulbar muscular atrophy (SBMA) is caused by a trinucleotide repeat expansion in the androgen receptor gene on the X chromosome. There is a toxic effect of the mutant receptor on muscle and neurons resulting in muscle weakness and atrophy. The weakness can be explained by wasting due to loss of muscle cells, but it is unknown whether weakness also relates to poor muscle contractility of the remaining musculature. In this study, we investigated the muscle contractility in SBMA. We used stationary dynamometry and quantitative MRI to assess muscle strength and absolute and fat-free, cross-sectional areas. Specific muscle force (strength per cross-sectional area) and contractility (strength per fat-free cross-sectional area) were compared with healthy controls and their relation to walking distance and disease severity was investigated. Specific force was reduced by 14-49% in SBMA patients compared to healthy controls. Contractility was reduced by 22-39% in elbow flexion, knee extension, ankle dorsi- and plantarflexion in SBMA patients. The contractility decreased with increasing muscle fat content in muscles with affected contractility in SBMA. The decreased muscle contractility in SBMA may relate to motor neuron degeneration and changed fibre type distribution and muscle architecture.
Topics: Adult; Aged; Aged, 80 and over; Bulbo-Spinal Atrophy, X-Linked; Chromosomes, Human, X; Cross-Sectional Studies; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Motor Neurons; Muscle Contraction; Muscle Strength; Muscle Strength Dynamometer; Muscle Weakness; Muscles; Nerve Degeneration; Receptors, Androgen; Trinucleotide Repeat Expansion
PubMed: 30886222
DOI: 10.1038/s41598-019-41240-y -
Scientific Reports Jan 2021The nuclear fertility restorer gene Rf5 in HA-R9, originating from the wild sunflower species Helianthus annuus, is able to restore the widely used PET1 cytoplasmic male...
The nuclear fertility restorer gene Rf5 in HA-R9, originating from the wild sunflower species Helianthus annuus, is able to restore the widely used PET1 cytoplasmic male sterility in sunflowers. Previous mapping placed Rf5 at an interval of 5.8 cM on sunflower chromosome 13, distal to a rust resistance gene R at a 1.6 cM genetic distance in an SSR map. In the present study, publicly available SNP markers were further mapped around Rf5 and R using 192 F individuals, reducing the Rf5 interval from 5.8 to 0.8 cM. Additional SNP markers were developed in the target region of the two genes from the whole-genome resequencing of HA-R9, a donor line carrying Rf5 and R. Fine mapping using 3517 F individuals placed Rf5 at a 0.00071 cM interval and the gene co-segregated with SNP marker S13_216392091. Similarly, fine mapping performed using 8795 F individuals mapped R at an interval of 0.00210 cM, co-segregating with two SNP markers, S13_225290789 and C13_181790141. Sequence analysis identified Rf5 as a pentatricopeptide repeat-encoding gene. The high-density map and diagnostic SNP markers developed in this study will accelerate the use of Rf5 and R in sunflower breeding.
Topics: Chromosome Walking; Chromosomes, Plant; Cloning, Molecular; Fertility; Genes, Plant; Genetic Linkage; Helianthus; Plant Breeding; Sequence Analysis, DNA
PubMed: 33437028
DOI: 10.1038/s41598-020-80659-6 -
GigaScience May 2018The teleost fish Monopterus albus is emerging as a new model for biological studies due to its natural sex transition and small genome, in addition to its enormous...
BACKGROUND
The teleost fish Monopterus albus is emerging as a new model for biological studies due to its natural sex transition and small genome, in addition to its enormous economic and potential medical value. However, no genomic information for the Monopterus is currently available.
FINDINGS
Here, we sequenced and de novo assembled the genome of M. albus and report the de novochromosome assembly by FISH walking assisted by conserved synteny (Cafs). Using Cafs, 328 scaffolds were assembled into 12 chromosomes, which covered genomic sequences of 555 Mb, accounting for 81.3% of the sequences assembled in scaffolds (∼689 Mb). A total of 18 ,660 genes were mapped on the chromosomes and showed a nonrandom distribution along chromosomes.
CONCLUSIONS
We report the first reference genome of the Monopterus and provide an efficient Cafs strategy for a de novo chromosome-level assembly of the Monopterus genome, which provides a valuable resource, not only for further studies in genetics, evolution, and development, particularly sex determination, but also for breed improvement of the species.
Topics: Animals; Chromosomes; Fishes; Genome; Multigene Family; Synteny; Whole Genome Sequencing
PubMed: 29688346
DOI: 10.1093/gigascience/giy046 -
Trends in Genetics : TIG Feb 1995The original concept behind map-based or positional cloning was to find a DNA marker linked to a gene of interest, and then to 'walk' to the gene via overlapping clones... (Review)
Review
The original concept behind map-based or positional cloning was to find a DNA marker linked to a gene of interest, and then to 'walk' to the gene via overlapping clones (e.g. cosmids or YACs). While chromosome walking is straightforward in organisms with small genomes, it is difficult to apply in most plant species, which typically have large, complex genomes. The strategy of chromosome walking is based on the assumption that it is difficult and time consuming to find DNA markers that are physically close to a gene of interest. Recent technological developments invalidate this assumption for many species. As a result, the mapping paradigm has now changed such that one first isolates one or more DNA marker(s) at a physical distance from the targeted gene that is less than the average insert size of the genomic library being used for clone isolation. The DNA marker is then used to screen the library and isolate (or 'land' on) the clone containing the gene, without any need for chromosome walking and its associated problems. Chromosome landing, together with the technology that has made it possible, is likely to become the main strategy by which map-based cloning is applied to isolate both major genes and genes underlying quantitative traits in plant species.
Topics: Chromosome Mapping; Cloning, Molecular; DNA, Plant; Gene Library; Genes, Plant; Genetic Linkage; Genetic Markers; Genome; Humans; Solanum lycopersicum; Plants
PubMed: 7716809
DOI: 10.1016/s0168-9525(00)88999-4 -
Cureus Nov 2022A 10-year-old female with a history of global developmental delay (reduced concentration, cognitive impairment, and difficulty in reading and writing), scoliosis,...
A 10-year-old female with a history of global developmental delay (reduced concentration, cognitive impairment, and difficulty in reading and writing), scoliosis, aggressiveness, toe walking, and brain malformations was observed in the pediatric development outpatient consultation of Hospital de Santo Espírito da Ilha Terceira (HSEIT), Azores, Portugal. A genetic study was carried out and showed a terminal 6q27 microdeletion, a rare disorder. Being so rare, it's important to share with the wider medical community any of such cases so early diagnosis can occur and interventions may be developed.
PubMed: 36475138
DOI: 10.7759/cureus.31037 -
Nucleic Acids Research Aug 2023The fidelity of alternative splicing (AS) patterns is essential for growth development and cell fate determination. However, the scope of the molecular switches that...
The fidelity of alternative splicing (AS) patterns is essential for growth development and cell fate determination. However, the scope of the molecular switches that regulate AS remains largely unexplored. Here we show that MEN1 is a previously unknown splicing regulatory factor. MEN1 deletion resulted in reprogramming of AS patterns in mouse lung tissue and human lung cancer cells, suggesting that MEN1 has a general function in regulating alternative precursor mRNA splicing. MEN1 altered exon skipping and the abundance of mRNA splicing isoforms of certain genes with suboptimal splice sites. Chromatin immunoprecipitation and chromosome walking assays revealed that MEN1 favored the accumulation of RNA polymerase II (Pol II) in regions encoding variant exons. Our data suggest that MEN1 regulates AS by slowing the Pol II elongation rate and that defects in these processes trigger R-loop formation, DNA damage accumulation and genome instability. Furthermore, we identified 28 MEN1-regulated exon-skipping events in lung cancer cells that were closely correlated with survival in patients with lung adenocarcinoma, and MEN1 deficiency sensitized lung cancer cells to splicing inhibitors. Collectively, these findings led to the identification of a novel biological role for menin in maintaining AS homeostasis and link this role to the regulation of cancer cell behavior.
Topics: Animals; Humans; Mice; Alternative Splicing; Genomic Instability; Lung Neoplasms; R-Loop Structures; RNA Polymerase II; RNA, Messenger
PubMed: 37395406
DOI: 10.1093/nar/gkad548 -
Journal of Neurochemistry Aug 2013One hundred and fifty years since Nikolaus Friedreich's first description of the degenerative ataxic syndrome which bears his name, his description remains at the core... (Review)
Review
One hundred and fifty years since Nikolaus Friedreich's first description of the degenerative ataxic syndrome which bears his name, his description remains at the core of the classical clinical phenotype of gait and limb ataxia, poor balance and coordination, leg weakness, sensory loss, areflexia, impaired walking, dysarthria, dysphagia, eye movement abnormalities, scoliosis, foot deformities, cardiomyopathy and diabetes. Onset is typically around puberty with slow progression and shortened life-span often related to cardiac complications. Inheritance is autosomal recessive with the vast majority of cases showing an unstable intronic GAA expansion in both alleles of the frataxin gene on chromosome 9q13. A small number of cases are caused by a compound heterozygous expansion with a point mutation or deletion. Understanding of the underlying molecular biology has enabled identification of atypical phenotypes with late onset, or atypical features such as retained reflexes. Late-onset cases tend to have slower progression and are associated with smaller GAA expansions. Early-onset cases tend to have more rapid progression and a higher frequency of non-neurological features such as diabetes, cardiomyopathy, scoliosis and pes cavus. Compound heterozygotes, including those with large deletions, often have atypical features. In this paper, we review the classical and atypical clinical phenotypes of Friedreich's ataxia.
Topics: Age of Onset; Animals; Cognition Disorders; Deglutition Disorders; Disease Progression; Eye Diseases; Friedreich Ataxia; Gait Disorders, Neurologic; Humans; Muscle Weakness; Neurologic Examination; Phenotype; Reflex; Sensation Disorders; Speech Disorders
PubMed: 23859346
DOI: 10.1111/jnc.12317 -
Molecular Autism Oct 2021The Autism Sequencing Consortium identified 102 high-confidence autism spectrum disorder (ASD) genes, showing that individuals with ASD and with potentially damaging...
BACKGROUND
The Autism Sequencing Consortium identified 102 high-confidence autism spectrum disorder (ASD) genes, showing that individuals with ASD and with potentially damaging single nucleotide variation (pdSNV) in these genes had lower cognitive levels and delayed age at walking, when compared to ASD participants without pdSNV. Here, we made use of a Swedish sample of individuals with ASD (called PAGES, for Population-Based Autism Genetics & Environment Study) to evaluate the frequency of pdSNV and their impact on medical and psychiatric phenotypes, using an epidemiological frame and universal health reporting. We then combine findings with those for potentially damaging copy number variation (pdCNV).
METHODS
SNV and CNV calls were generated from whole-exome sequencing and chromosome microarray data, respectively. Birth and medical register data were used to collect phenotypes.
RESULTS
Of 808 individuals assessed by sequencing, 69 (9%) had pdSNV in the 102 ASC genes, and 144 (18%) had pdSNV in the 102 ASC genes or in a larger set of curated neurodevelopmental genes (from the Deciphering Developmental Disorders study, the gene2phenotype database, and the Radboud University gene lists). Three or more individuals had pdSNV in GRIN2B, POGZ, SATB1, DYNC1H1, SCN8A, or CREBBP. In comparison, out of the 996 individuals from whom CNV were called, 105 (11%) carried one or more pdCNV, including four or more individuals with CNV in the recurrent 15q11q13, 22q11.2, and 16p11.2 loci. Carriers of pdSNV were more likely to have intellectual disability (ID) and epilepsy, while carriers of pdCNV showed increased rates of congenital anomalies and scholastic skill disorders. Carriers of either pdSNV or pdCNV were more likely to have ID, scholastic skill disorders, and epilepsy.
LIMITATIONS
The cohort only included individuals with autistic disorder, the more severe form of ASD, and phenotypes are defined from medical registers. Not all genes studied are definitively ASD genes, and we did not have de novo information to aid in classification.
CONCLUSIONS
In this epidemiological sample, rare pdSNV were more common than pdCNV and the combined yield of potentially damaging variation was substantial at 27%. The results provide compelling rationale for the use of high-throughout sequencing as part of routine clinical workup for ASD and support the development of precision medicine in ASD.
Topics: Autism Spectrum Disorder; Autistic Disorder; DNA Copy Number Variations; Humans; Matrix Attachment Region Binding Proteins; Phenotype; Prevalence; Transposases
PubMed: 34615535
DOI: 10.1186/s13229-021-00465-3 -
Medicina Oral, Patologia Oral Y Cirugia... Jan 2011Rett syndrome (RS) is a chromosome X-linked genetic neurological disorder characterized by developmental regression, particularly in relation to expressive language and... (Review)
Review
Rett syndrome (RS) is a chromosome X-linked genetic neurological disorder characterized by developmental regression, particularly in relation to expressive language and use of the hands, together with profound mental retardation, that almost exclusively affects females. The present review describes the 35 cases of RS published in the indexed literature (Medline)--the first corresponding to 1985 and the last to the year 2007. Certain oral manifestations of the disease are derived from the drug treatment prescribed to control the disease, while others are common to other clinical conditions characterized by convulsion activity, difficulties for correct oral hygiene, walking problems and/or an excess of oral/digital-manual habits. In any case, bruxism is the oral habit most frequently associated with RS--the treatment of which remains the subject of controversy.
Topics: Bruxism; Child; Female; Humans; Mouth Diseases; Rett Syndrome
PubMed: 20526264
DOI: 10.4317/medoral.16.e37