Case Report: A female case of X-linked intellectual disability syndrome type 34 caused by a NONO frameshift variant and literature review

We report the first molecularly confirmed female MRXS34 patient. Her full phenotypic manifestation is attributed to the <i>de novo</i> NONO loss-of-function variant combined with extreme non-random XCI. This case critically expands the clinical spectrum of MRXS34, underscores the diagnostic importance of XCI analysis in females with XLID phenotypes, and provides insights into the mechanisms enabling female expression of X-linked recessive disorders.