A Novel SON Gene Variant Associated with Rare Clinical Features in ZTTK Syndrome: A Case Report and Literature Review.

Introduction: Zhu-Tokita-Takenouchi-Kim (ZTTK) syndrome is a rare multisystemic congenital disorder caused by SON gene variants. This study aimed to present the results of whole exome sequencing, and describe some rare findings observed in the proband.

Case presentation: An 11-year-old boy exhibited hypotonia, poor growth, short stature, and microcephaly. The patient displayed various neurological symptoms, such as developmental delay, seizures, hydrocephalus, and brain abnormalities. He presented with strabismus, urinary problems, and facial dysmorphism. A history of stroke, obsession, insomnia, self-injurious behavior, and hearing loss was also noted. Based on the patient's clinical findings, whole exome sequencing was performed. A novel variant in the SON gene was identified. This variant was confirmed by Sanger sequencing. Notably, the parents tested normal for the variant.

Conclusion: This study presents a patient who exhibited a wide range of behavioral abnormalities, stroke, and recurrent urolithiasis - features that are rarely reported in ZTTK syndrome - and includes a review of the literature.