SNP Shot: Genomic Insights

Smith-Kingsmore syndrome is a neurological condition marked by macrocephaly (an abnormally large head), intellectual disability, and seizures. Speech development can be delayed or absent in some individuals. ADHD and autism spectrum disorder, which affects communication and social skills, are also observed in some children with this syndrome. Individuals may exhibit structural abnormalities in the brain, such as hemimegalencephaly or megalencephaly (enlargement of one or both brain hemispheres), polymicrogyria (excessive folding of the brain surface), or ventriculomegaly (enlarged ventricles).

Distinctive facial features are common in individuals with Smith-Kingsmore syndrome, but not always present. These features may include a triangular face with a pointed chin, frontal bossing (a prominent forehead), hypertelorism (widely spaced eyes) with downslanting palpebral fissures (downward-sloping corners of the eyes), a flat nasal bridge, or a long philtrum (the area between the nose and upper lip).

Inheritance:

Smith-Kingsmore syndrome is inherited in an autosomal dominant manner, meaning that only one copy of the mutated gene is needed to cause the condition. In most cases, the mutation arises spontaneously (de novo) during the formation of egg or sperm cells in a parent or during early development of the embryo. In rare instances, the affected individual inherits the mutated gene from a parent who doesn't have the syndrome but carries the MTOR gene mutation in their germline cells (sperm or egg), a situation known as germline mosaicism.