Epigenetic modifications of the X chromosome in families with miscarriage

Асимметричная инактивация Х-хромосомы характерна как для женщин с привычным невынашиванием, так и для спонтанных абортусов с кариотипом 46,XX, а смещение инактивации у спонтанного абортуса чаще связано с наличием асимметричной инактивации у матери. Skewed inactivation of the X chromosome is characteristic for women with recurrent pregnancy loss and spontaneous abortions with a karyotype 46,XX. Skewed X-inactivation in spontaneous abortion is more often associated with the asymmetric inactivation in the mother.

Two Abnormal Cell Lines of Trisomy 14 and t(X;14) with Skewed X-Inactivation

Trisomy 14 is incompatible with live, but there are several patients reported with mosaic trisomy 14. We aimed to study the pattern of X inactivation and its effect on a translocated autosome and to find out an explanation of the involvement of chromosome 14 in 2 different structural chromosomal abnormalities. We report on a girl with frontal bossing, hypertelorism, low-set ears, micrognathia, cleft palate, congenital heart disease, and abnormal skin pigmentations. The patient displayed iris, choroidal, and retinal coloboma and agenesis of the corpus callosum and cerebellar vermis hypoplasia. Cytogenetic analysis revealed a karyotype 45,X,der(X)t(X;14)(q24;q11)[85]/46,XX,rob(14;14)(q10;q10),+14[35]. Array-CGH for blood and buccal mucosa showed high mosaic trisomy 14 and an Xq deletion. MLPA detected trisomy 14 in blood and buccal mucosa and also showed normal methylation of the imprinting center. FISH analysis confirmed the cell line with trisomy 14 (30%) and demonstrated the mosaic deletion of the Xq subtelomere in both tissues. There was 100% skewed X inactivation for the t(X;14). SNP analysis of the patient showed no region of loss of heterozygosity on chromosome 14. Also, genotype call analysis of the patient and her parents showed heterozygous alleles of chromosome 14 with no evidence of uniparental disomy. Our patient had a severe form of mosaic trisomy 14. We suggest that this cytogenetic unique finding that involved 2 cell lines with structural abnormalities of chromosome 14 occurred in an early postzygotic division. These 2 events may have happened separately or maybe there is a kind of trisomy or monosomy rescue due to dynamic cytogenetic interaction between different cell lines to compensate for gene dosage.

Heritability of skewed X-inactivation in female twins is tissue-specific and associated with age

Female somatic X-chromosome inactivation (XCI) balances the X-linked transcriptional dosages between the sexes. Skewed XCI toward one parental X has been observed in several complex human traits, but the extent to which genetics and environment influence skewed XCI is largely unexplored. To address this, we quantify XCI-skew in multiple tissues and immune cell types in a twin cohort. Within an individual, XCI-skew differs between blood, fat and skin tissue, but is shared across immune cell types. XCI skew increases with age in blood, but not other tissues, and is associated with smoking. XCI-skew is increased in twins with Rheumatoid Arthritis compared to unaffected identical co-twins. XCI-skew is heritable in blood of females >55 years old (h2 = 0.34), but not in younger individuals or other tissues. This results in a Gene x Age interaction that shifts the functional dosage of all X-linked heterozygous loci in a tissue-restricted manner.

THE IMPACT OF SKEWED X-INACTIVATION IN SPINAL MUSCULAR ATROPHY PHENOTYPE MODIFICATION

THE IMPACT OF SKEWED X-INACTIVATION IN SPINAL MUSCULAR ATROPHY PHENOTYPE MODIFICATION

Childhood Dystonia-Parkinsonism Following Infantile Spasms—Clinical Clue to Diagnosis in Early Beta-Propeller Protein-Associated Neurodegeneration

Introduction Beta-propeller protein-associated neurodegeneration (BPAN) is a very rare, X-linked dominant (XLD) inherited member of the neurodegeneration with brain iron accumulation (NBIA) disease family. Case report We present a female case of BPAN with infantile spasms in the first year, Rett-like symptomatology, focal epilepsy, and loss of motor skills in childhood. Menarche occurred at the age of 9, after precocious pubarche and puberty.Dystonia-parkinsonism as extrapyramidal sign at the age of 10 years resulted in radiological and genetic work-up. Results Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS) measured 66/120 points in body part-related dystonia symptoms. Cerebrospinal fluid examination showed dopamine depletion.T2 and B0 sequences of the diffusion-weighted magnetic resonance imaging showed susceptibility artifacts with NBIA-typical hypointense globus pallidus (GP) and substantia nigra (SN). Next-generation sequencing revealed a BPAN-causing pathogenic variant in WDR45 (WD repeat-containing protein 45) gene (c.830 + 1G > A, XLD, heterozygous, de novo). Skewed X-inactivation was measured (2:98). Conclusions Autophagy-related X-linked BPAN disease might still be underdiagnosed in female cases of infantile spasms.Skewed X-inactivation will have mainly influenced the uncommon, very early childhood neurodegenerative symptomatology in the present BPAN case. Oral levodopa substitution led to improvement in sleep disorder, hypersalivation, and swallowing.Reduced white matter and hypointense signals in SN and GP on susceptibility sequences in magnetic resonance imaging are characteristic radiological findings of advanced disease in NBIA. No BPAN-typical halo sign in T1-weighted scan at midbrain level was seen at the age of 11 years. NBIA panel is recommended for early diagnosis.

Skewed X-inactivation in a Female Carrier with X-linked Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency caused by defective phagocytic NADPH oxidase, causing a complete lack or significant decrease in the production of microbicidal reactive oxygen metabolites. It mainly affects male children; however, there are scarce reports of adult females diagnosed with X-linked-CGD attributed to an extremely skewed X-chromosome inactivation. This condition is characterized by severe and recurrent infections that usually develop after childhood. In clinical practice, physicians who usually confront these patients should suspect this entity and differentiate it from a secondary immunodeficiency. Here, we report a 38-year-old Mexican female with juvenile-onset X linked-CGD, caused by a de novo mutation and extremely skewed X-inactivation, whose clinical features were similar to those in patients with classic X-linked-CDG.