Long-term follow-up and novel variant in Suleiman-El-Hattab syndrome: Expanding the genotypic and clinical spectrum of a rare neurodevelopmental disorder.

Suleiman-El-Hattab syndrome (SULEHS, OMIM #618950) is an autosomal recessive multisystem developmental disorder characterized by distinctive facial appearance, global developmental delay/intellectual disability, poor expressive speech and happy demeanor. SULEHS is an ultra-rare disorder associated with biallelic loss-of-function variants of the TASP1 gene, and up-to-date, seven patients from five families have been reported in the literature. Loss of TASP1 function has been reported to alter H3K4 histone modifications and expression of TFIIA and HOX transcription factors in the SULEHS phenotype. In this report, a new patient molecularly diagnosed with SULEHS by a novel homozygous c.404-2A > G variant in the TASP1 gene is presented with the long-term follow-up. Although the majority of the patient's clinical characteristics were similar to those of previously reported SULEHS patients, this study was the first to describe some additional anomalies, such as cystic hygroma, increased nuchal thickness, coarctation of the aorta, pulmonary stenosis, pulmonary sequestration anomaly, chronic constipation, encephalomalacia, and aggressive behavior. Because of the remarkable similarities between the clinical features of Baraitser-Winter syndrome (BRWS) and the patient, BRWS was considered the most likely diagnosis before the molecular diagnosis. Network analysis also supported that the interaction of the SULEHS-associated TASP1 gene with the BRWS-associated ACTB and ACTG1 genes through common intermediate molecules. Overall, despite the existence of differences in clinical features, inheritance patterns, and underlying pathophysiology between BRWS and SULEHS, both diseases could be considered in the differential diagnosis due to the high clinical similarities, including the dysmorphic features, growth parameters, neurodevelopmental phenotype, neurological problems, and multisystem involvement. Additionally, this report could contribute to a better understanding of the genotypic and clinical features of SULEHS by describing a novel pathogenic variant and new clinical features, such as prenatal manifestations.