X chromosome

About: X chromosome is a research topic. Over the lifetime, 9862 publications have been published within this topic receiving 407354 citations. The topic is also known as: GO:0000805 & chrX.

X-linked Wiskott-Aldrich syndrome in a girl.

Abstract: The Wiskott–Aldrich syndrome is a life-threatening X-linked recessive disorder. Affected males present with recurrent infections, eczema, and thrombocytopenia with small platelets. The immune defect involves both humoral and cellular immunity and increases in severity with age.1 The gene involved in this disease, located on the short arm of the X chromosome in the region Xp11.22–23, was recently cloned and named the Wiskott–Aldrich syndrome protein (WASP) gene.2,3 Different mutations or deletions within the WASP gene have been described in patients with the Wiskott–Aldrich syndrome and X-linked thrombocytopenia.4 The gene is expressed in early progenitor cells as well as . . .

The male-specific lethal-one (msl-1) gene of Drosophila melanogaster encodes a novel protein that associates with the X chromosome in males.

Abstract: Male-specific lethal-one (msl-1) is one of four genes that are required for dosage compensation in Drosophila males. To determine the molecular basis of msl-1 regulation of dosage compensation, we have cloned the gene and characterized its products. The predicted msl-1 protein (MSL-1) has no significant similarity to proteins in the current data bases but contains an acidic N terminus characteristic of proteins involved in transcription and chromatin modeling. We present evidence that the msl-1 protein is associated with hundreds of sites along the length of the X chromosome in male, but not in female, nuclei. Our findings support the hypothesis that msl-1 plays a direct role in increasing the level of X-linked gene transcription in male nuclei.

Analysis of the chromosome X exome in patients with autism spectrum disorders identified novel candidate genes, including TMLHE

Abstract: The striking excess of affected males in autism spectrum disorders (ASD) suggests that genes located on chromosome X contribute to the etiology of these disorders. To identify new X-linked genes associated with ASD, we analyzed the entire chromosome X exome by next-generation sequencing in 12 unrelated families with two affected males. Thirty-six possibly deleterious variants in 33 candidate genes were found, including PHF8 and HUWE1, previously implicated in intellectual disability (ID). A nonsense mutation in TMLHE, which encodes the ɛ-N-trimethyllysine hydroxylase catalyzing the first step of carnitine biosynthesis, was identified in two brothers with autism and ID. By screening the TMLHE coding sequence in 501 male patients with ASD, we identified two additional missense substitutions not found in controls and not reported in databases. Functional analyses confirmed that the mutations were associated with a loss-of-function and led to an increase in trimethyllysine, the precursor of carnitine biosynthesis, in the plasma of patients. This study supports the hypothesis that rare variants on the X chromosome are involved in the etiology of ASD and contribute to the sex-ratio disequilibrium.

Translocation (X;6) in a female with Duchenne muscular dystrophy: implications for the localisation of the DMD locus.

Abstract: A female with Duchenne muscular dystrophy who was a carrier of a balanced translocation t(X;6)(p21;q21) is reported. Four other previously described (X;A) translocations associated with DMD share with the present case a breakpoint at Xp21. The extremely low probability of five independent (X;A) translocations having a breakpoint at Xp21 points to a non-rand association of this site with the DMD phenotype. A DMD locus at Xp21 could be damaged by the translocation, giving rise to Duchenne muscular dystrophy. Alternatively, a pre-existing DMD gene could weaken the chromosome, favouring breaks at Xp21.