SNP Shot: Genomic Insights

Multiple sulfatase deficiency (MSD) is a disorder primarily impacting the brain, skin, and skeleton. Due to the wide range of symptoms and their severity, MSD is categorized into three subtypes: neonatal, late-infantile, and juvenile.

The neonatal form is the most severe, with symptoms appearing shortly after birth. Affected infants experience leukodystrophy, a deterioration of nervous system tissue, leading to movement difficulties, seizures, developmental delays, and slowed growth. They also exhibit ichthyosis (dry, scaly skin) and hypertrichosis (excessive hair growth). Skeletal problems may include scoliosis (spinal curvature), joint stiffness, and dysostosis multiplex, a distinctive pattern of skeletal abnormalities visible on X-rays. Individuals with the neonatal type often have "coarse" facial features and may also develop hearing loss, heart defects, and hepatosplenomegaly (enlarged liver and spleen). The symptoms of neonatal MSD typically worsen with time.

The late-infantile form is the most prevalent type of MSD. It's marked by normal cognitive development in early childhood, followed by psychomotor regression, a progressive loss of mental and motor skills, caused by leukodystrophy or other brain issues. While individuals with this form generally exhibit fewer features than those with the neonatal type, they frequently have ichthyosis, skeletal abnormalities, and coarse facial features.

The juvenile form is the rarest type of MSD. Symptoms of the juvenile type emerge in mid- to late childhood. Affected children initially develop normally cognitively but then experience psychomotor regression. However, the regression progresses more slowly compared to the late-infantile type. Ichthyosis is also a common feature of the juvenile form.

Individuals with all types of MSD have a reduced life expectancy. Survival is usually limited to a few years after the onset of symptoms, but the exact lifespan varies depending on the severity of the condition and the rate of neurological decline.

Inheritance:

MSD is inherited in an autosomal recessive manner. This means that both copies of the relevant gene in each cell must have mutations for the condition to develop. Individuals with autosomal recessive disorders inherit one copy of the mutated gene from each parent, who are carriers of the gene but typically do not exhibit symptoms of the condition themselves.