SNP Shot: Genomic Insights

Schimke immuno-osseous dysplasia (SIOD) is a disorder defined by three primary features: short stature, kidney problems, and a compromised immune system. The short stature in SIOD is due to flattened vertebrae in the spine, leading to a shortened neck and trunk. Affected individuals typically reach an adult height of 3 to 5 feet. The kidney disease often progresses to life-threatening renal failure and end-stage renal disease (ESRD). Additionally, individuals with SIOD have a deficiency of T cells, which are crucial for identifying and fighting off infections, making them more vulnerable to illness.

Other common characteristics of SIOD include an accentuated curve in the lower back (lordosis), areas of darkened skin (hyperpigmentation) usually on the chest and back, and a wide nasal bridge with a rounded nasal tip.

Less frequently, individuals with SIOD may experience fatty deposits and scarring in the arteries (atherosclerosis), reduced blood flow to the brain (cerebral ischemia), migraine headaches, an underactive thyroid (hypothyroidism), low white blood cell count (lymphopenia), underdeveloped hip bones (hypoplastic pelvis), abnormally small head size (microcephaly), absence of sperm in males (azoospermia), and irregular periods in females.

The severity of SIOD varies; some individuals exhibit many symptoms at birth, while others with milder cases may not show signs until later in childhood.

Inheritance:

SIOD is caused by mutations in the SMARCAL1 gene and follows an autosomal recessive inheritance pattern. This means that to develop SIOD, a person must inherit a mutated copy of the SMARCAL1 gene from both parents. While both parents carry one copy of the mutated gene, they usually do not display any symptoms of the disorder themselves.