Exploring the Clinical Spectrum of HUWE1 -Related Neurodevelopmental Disorder: Five New Patients and Literature Review.

Turner-type X-linked syndromic intellectual developmental disorder (MRXST) is a neurodevelopmental disorder associated with variants in the HUWE1 gene on chromosome Xp11. The condition is characterized by variable phenotypes, including global developmental delay, intellectual disability, and distinctive facial dysmorphisms, with inheritance patterns ranging from X-linked recessive to de novo mutations in females. Here, we describe five probands in two families, highlighting their clinical features and genetic findings. Trio whole-exome sequencing identified a de novo variant in HUWE1 in the proband in one family and a maternally inherited hemizygous variant in three boys in a second family. A comprehensive review of HUWE1-associated cases from the literature assisted genotype-phenotype correlations, revealing consistent features such as intellectual disability, skeletal anomalies, and facial dysmorphisms as well as instances of intrafamilial variability. Our findings confirm the phenotypic variability of MRXST and underscore the significance of the HUWE1 gene product in neurodevelopment. We propose a baseline monitoring protocol to aid in diagnosis and management, contributing to the development of specific guidelines for patient follow-up.