SNP Shot: Genomic Insights

Sotos syndrome is a genetic condition marked by distinct facial features, accelerated growth during childhood, and challenges in learning or delays in mental and motor skill development. Key facial characteristics include a long, thin face, a prominent forehead, red cheeks, and a small, pointed chin. The outer corners of the eyes may also slant downwards. These facial features are most pronounced in young children. Infants and children with Sotos syndrome tend to experience rapid growth, exceeding the height of their siblings and peers, and often have a larger than average head size. However, their adult height usually falls within the normal range.

Individuals with Sotos syndrome frequently experience intellectual disabilities and often have neurodevelopmental disorders. Common co-occurring conditions include autism spectrum disorder, attention-deficit/hyperactivity disorder (ADHD), phobias, obsessive-compulsive behaviors, temper tantrums, and impulsive actions. Speech and language difficulties are also prevalent, manifesting as stuttering, a flat or monotonous voice, and problems with pronunciation. Furthermore, low muscle tone (hypotonia) can delay early developmental milestones, particularly motor skills like sitting and crawling.

Other potential signs and symptoms of Sotos syndrome may include scoliosis (an abnormal curvature of the spine), seizures, heart or kidney abnormalities, hearing impairment, and vision problems. Some infants with Sotos syndrome may also experience jaundice (yellowing of the skin and eyes) and feeding difficulties.

A small percentage of individuals with Sotos syndrome have developed cancer, primarily during childhood. However, no single cancer type is particularly associated with the condition. It is still unclear whether Sotos syndrome significantly elevates the risk of specific cancers. If there is an increased risk, it is only marginally higher compared to the general population.

Inheritance:

Approximately 95% of Sotos syndrome cases arise spontaneously, with no prior family history of the condition. These cases typically stem from new (de novo) mutations in the NSD1 gene. A few families have been identified with multiple affected members. These familial cases have helped establish that Sotos syndrome follows an autosomal dominant inheritance pattern. This means that only one copy of a mutated gene in each cell is enough to cause the disorder.