X-chromosome inactivation patterns in females with Fabry disease examined by both ultra-deep RNA sequencing and methylation-dependent assay.

Rini Rossanti,Tomohiko Yamamura,Tomoko Horinouchi,Kazumoto Iijima,Noritoshi Kato,Shogo Minamikawa,Kandai Nozu,Shinya Ishiko,Atsushi Fukunaga,Yuya Aoto,Hideki Fujii,Nana Sakakibara,China Nagano,Keiji Kono,Takeshi Ninchoji,Shinichi Nishi,Eri Okada,Shoichi Maruyama

doi:10.1007/s10157-021-02099-4

Rini Rossanti, Tomohiko Yamamura + Show 16 more

Open Access

https://doi.org/10.1007/s10157-021-02099-4

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Abstract

Fabry disease is an X-linked inherited lysosomal storage disorder caused by mutations in the gene encoding α-galactosidase A. Males are usually severely affected, while females have a wide range of disease severity. This variability has been assumed to be derived from organ-dependent skewed X-chromosome inactivation (XCI) patterns in each female patient. Previous studies examined this correlation using the classical methylation-dependent method; however, conflicting results were obtained. This study was established to ascertain the existence of skewed XCI in nine females with heterozygous pathogenic variants in the GLA gene and its relationship to the phenotypes. We present five female patients from one family and four individual female patients with Fabry disease. In all cases, heterozygous pathogenic variants in the GLA gene were detected. The X-chromosome inactivation patterns in peripheral blood leukocytes and cells of urine sediment were determined by both classical methylation-dependent HUMARA assay and ultra-deep RNA sequencing. Fabry Stabilization Index was used to determine the clinical severity. Skewed XCI resulting in predominant inactivation of the normal allele was observed only in one individual case with low ⍺-galactosidase A activity. In the remaining cases, no skewing was observed, even in the case with the highest total severity score (99.2%). We conclude that skewed XCI could not explain the severity of female Fabry disease and is not the main factor in the onset of various clinical symptoms in females with Fabry disease.

Highlights

Fabry disease is an X-linked inherited lysosomal storage disorder related to GLA mutations, gene encoding α-galactosidase A
The aim of this study is to evaluate whether X-chromosome inactivation (XCI) favoring in the mutant ⍺-galactosidase A exist in our cohort of female heterozygotes with Fabry disease
We recently developed a novel assay of ultra-deep RNA sequencing for examining XCI patterns [17] that uses the quantification of transcript expression for wild-type and variant alleles

Summary

Introduction

Fabry disease is an X-linked inherited lysosomal storage disorder related to GLA mutations, gene encoding α-galactosidase A. Fabry disease (OMIM #301500), is a rare lysosomal disorder that characterized by multi-system involvement due to deficiency of ⍺-galactosidase A, which is required for globotriosyl-ceramide (Gb3) degradation [1] This enzyme is encoded by the GLA gene, located on the X chromosome. As a result of enzyme deficiency, the accumulation of undegraded substrates, Gb3 and deacylated globotriaosylsphingosine (lyso-Gb3), results in the earliest symptoms in patients with the classic form of this disorder, including neuropathic pain, vascular skin lesions, sweating abnormalities, characteristic ocular changes, gastrointestinal problems, temperature intolerance, or proteinuria [1, 7]. It was reported that the average life expectancy was reduced by 5.75% in females and 22% in males, with the most common cause of death was cardiovascular disease in both sexes [1, 8]

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