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1,502 records · Page 84Linked to original sources
PubMed1998

Molecular cytogenetic analysis in splenic lymphoma with villous lymphocytes: frequent allelic imbalance of the RB1 gene but not the D13S25 locus on chromosome 13q14.

Structural abnormalities of chromosome 13q are one of the most frequent genetic aberrations in human tumors. 13q rearrangements are, however, infrequent in splenic lymphoma with villous lymphocytes (SLVL) by karyotype analysis. We have investigated the incidence of 13q14 deletions in a series of 74 SLVL cases by interphase fluorescence in situ hybridization using unique sequence probes for the RB1 and the D13S25 loci, which are frequently deleted in chronic lymphocytic leukemia. Chromosome 12 was also evaluated by fluorescence in situ hybridization using a pericentromeric DNA probe. 13q14 deletion was detected in 37 of 74 (50%) tumors. Thirty-five cases (47%) exhibited monoallelic loss of RB1, and 9 (12%) showed hemizygous D13S25 deletion. Seven cases displayed coexistence of RB1 and D13S25 deletion. Trisomy 12 was detected in 2 of 74 (3%) tumors. G-banding analysis in 40 tumors showed no interstitial deletion of 13q14 in any case. In contrast with the molecular findings observed in chronic lymphocytic leukemia, our results indicate that trisomy 12 is an uncommon chromosomal aberration in SLVLs, and microdeletion of 13q14 at the RB1 locus but not D13S25 is a frequent and specific genetic event in this disease, suggesting that allelic loss of the RB1 gene may play a role in the pathogenesis of SLVL.

Aged↗
PubMed1998

[Y chromosome and male infertility].

Spermatogenesis is a complex physiological process characterized by an orderly proliferation and differentiation of germ cell types, from diploid spermatogonial stem cells to haploid spermatids, and after spermiogenesis to spermatozoa. It is known that male reproductive capacity is deficient in about one half of infertile couples. Effective treatment is available only for a small fraction of these infertile men. In most cases, the cause of male infertility is unknown. Aetiologically, male infertility may result from genetic and non-genetic causes. Among the genetic factors known to disturb spermatogenesis, chromosomal aberrations, involving autosomes and/or sex chromosomes, are well known. However, molecular genetic causes of idiopathic male infertility have been accumulating in the last years, predominantly for the Y chromosome. Localization of genes that control spermatogenesis on Yq11 was first proposed, on cytogenetic evidence, by Tiepolo and Zuffardi in 1976. Since then, many subsequent reports using molecular genetics methods have supported the initial proposal by detecting submicroscopic interstitial deletions on Yq11, present in patients with idiophatic azoospermia and a cytogenetically normal Y chromosome. Recently, four spermatogenesis candidate Y-linked genes (or gene families), RBM, DAZ, SPGY and TSPY have been cloned and characterized. In the euchromatic Y chromosome long arm three intervals--AZFa, AZFb and AZFc--were also defined. All of them may contain genes necessary for normal spermatogenesis. All the four genes have a testis-specific expression and three of them (RBM, DAZ and SPGY) code for ribonucleoproteins with a single RNA recognition motif. Candidate genes with in AZFb are some members of the RBM gene family and within AZFc are the DAZ and SPGY gene family. While AZFc deletions are associated with azoospermia or with severe oligoteratoasthenozoospermia, microdeletions involving AZFa or AZFb cause azoospermia only.

Chromosome Mapping↗
PubMed1998

Phenotypic discordance in monozygotic twins with 22q11.2 deletion.

We report on male monozygotic twins with 22q11.2 deletion and discordant phenotypes. The twins had twin-to-twin transfusion syndrome. Twin 1, the smaller of the pair, had Tetralogy of Fallot, a characteristic facial appearance, swallowing dysfunction, anal atresia, short stature, and mental retardation, whereas twin 2 had a characteristic facial appearance but no other signs of the 22q11 deletion syndrome. Fluorescence in situ hybridization analysis showed a microdeletion on chromosome 22q11.2 in both twins. Zygosity analysis gave a probability of monozygosity greater than 99.999%. These observations indicate that environmental factors or postzygotic events play a role in the phenotypic variability in the twins.

Abnormalities, Multiple↗
PubMed1998

[WAGR syndrome: a case report].

OBJECTIVE: WAGR syndrome is a rare syndrome which involves microdeletions of the short arm of chromosome 11 at band 11p13. The clinical features are Wilms' tumor, amiridia, genitourinary abnormalities and mental retardation. There are very few reported cases. We report a new case of WAGR syndrome and review the literature. PATIENTS AND METHODS: Chromosome preparations were obtained from lymphocyte cultures of peripheral blood. For chromosome analysis GTG banding and fluorescent "in situ" hybridization (FISH) were used. RESULTS: Chromosomal analysis revealed deletion of p12-p13 bands. Our patient had bilateral aniridia, Wilms' tumor and cryptorquidia. CONCLUSIONS: The karyotype was 46, XY, del (11)(p12-p13). The p13 band deletion was the cause of the WAGR syndrome.

Chromosomes, Human, Pair 11↗
PubMed1999

Spinal muscular atrophy: untangling the knot?

Spinal muscular atrophy (SMA), a clinically and genetically heterogeneous group of neuromuscular diseases, is a disorder of motor neurones characterised by degeneration of spinal cord anterior horn cells and muscular atrophy. SMA is an autosomal recessive disorder with a carrier frequency of about 1150. Three candidate genes, the survival motor neurone (SMN) gene, the neuronal inhibitory protein (NAIP) gene, and the p44 (subunit of basal transcription factor TFIIH) gene, have been considered as genes involved in this condition. The region spanning these genes has a complex organisation including duplications, repetitive sequences, truncated genes, and pseudogenes, which makes molecular analysis of this condition difficult. Although deletions have been found in the majority of SMA patients, a few microrearrangements (like duplications, missense mutations, microdeletions, and gene conversions) localised in the telomeric form of the SMN gene have also been reported. The function of the protein encoded by the SMN gene is still not fully understood but recent studies have indicated that it is found intracellularly in gems, novel nuclear structures. Its interaction with other proteins suggests a role in mRNA processing and metabolism. Whether the NAIP gene protein and other apoptosis associated proteins are directly involved in the initial stages of neurone degeneration and apoptosis, or acting downstream on the pathological pathway, has been difficult to determine. Further studies will be required to elucidate possible functional interactions between these proteins.

Autoantigens↗
PubMed2025

Optical mapping in Black genomes: Distinct LCR22 structures and 22q11.2 deletion syndrome mechanisms.

PURPOSE: The genomic architecture of 22q11.2 deletion syndrome (22q11.2DS) has primarily been studied in White populations, despite evidence suggesting a lower prevalence in Black individuals. This study aims to improve our understanding of the population-specific organization of 22q11.2 genomic structures. METHODS: Optical mapping data from 106 genomes, representing various Black and White individuals, were analyzed to assess the structure and variation of the 22q11.2 low copy repeats (LCR22s). RESULTS: Extensive variability in copy-number and orientation of LCR22 elements was observed between Black and White genomes. Several novel copy-number variants and haplotype configurations were identified, some being private or more prevalent within specific groups. Notably, copy-number variants diversity was particularly striking among Black genomes. Comparisons of Black and White families with de novo 22q11.2DS probands revealed unique nonallelic homologous recombination scenarios, with Black families exhibiting recombination patterns that are not previously observed. CONCLUSION: Perhaps the unique and highly variable LCR22 haplotype configurations in Black individuals contribute to the lower observed prevalence of 22q11.2DS by inhibiting the likelihood of nonallelic homologous recombination, the mechanism that leads to the syndrome.

Humans↗
PubMed2026

Ocular Nystagmus as the Initial Presenting Feature in a Patient with Complete CLTC Deletion: Expanding the Genotype-Phenotype Spectrum of CLTC-Related Disorder.

Background: CLTC-related neurodevelopmental disorder is a rare condition primarily characterized by global developmental delay (GDD) and intellectual disability (ID). To date, approximately 41 cases involving CLTC gene alterations have been reported. We present the first individual with a complete deletion of the CLTC gene. Methods: The proband is a male from a non-consanguineous family, presenting with congenital nystagmus, hypotonia, GDD, and autism spectrum disorder (ASD). Chromosomal microarray analysis and trio exome sequencing were performed. A systematic review of previously reported CLTC variant cases was conducted to delineate the phenotypic spectrum. Results: A de novo 363-kb heterozygous deletion at 17q23.1 spanning the entire CLTC gene was identified. The systematic review confirmed GDD/ID as core features and revealed various ocular abnormalities in a subset of cases. These findings indicate that the clinical phenotype extends beyond neurodevelopment, with multi-system involvement. Conclusions: The phenotypic heterogeneity of CLTC-related disorders underscores the need for comprehensive physical examination to identify extra-neurological manifestations. Accurate diagnosis relies on integrating detailed clinical phenotyping with comprehensive genomic testing. Early, precise diagnosis facilitates multidisciplinary management, informed genetic counseling, and the establishment of long-term surveillance protocols.

Humans↗