Signs and Symptoms
The multiple symptoms of SIOD and the relative frequency of them are listed below. The symptoms are subsequently discussed according to the organ system affected.
All of this information was taken from The National Organization For Rare Disorders
Most affected individuals have distinctive physical features. These include fine hair (60%), a thin upper lip, a broad, low nasal bridge (68%), a bulbous nasal tip (83%), and disproportionately short stature (98%).
Additional features include excessive inward curvature of the lumbar spine (lumbar lordosis, 84%), a protruding abdomen, and hyperpigmented macules (85%) on the trunk and occasionally on the neck, face, arms and legs. Less common physical features include absent or small teeth and corneal opacities (19%).
Growth failure, which is often the first obvious sign of SIOD, occurs despite normal growth hormone production and is not corrected with growth hormone supplementation. In most affected individuals, the growth failure begins prior to and continues after birth; however, some affected children do have normal birth lengths and weights and their growth failure is not noted until after birth (range: 0 to 13 years, mean: 2 years). The heights of those who survived to adulthood were 136-157 cm for men and 98.5-143 cm for women.
The short stature arises generally because of spondyloepiphyseal dysplasia (86%), a disorder of skeletal growth; it does not arise as a complication of their renal failure. The anthropometric characteristics of patients with SIOD differ markedly from those of patients with other forms of chronic kidney disease, especially with respect to median leg length and sitting height. The spinal column and hip joint are most severely affected. The radiological abnormalities include ovoid or mildly flattened vertebral bodies, small and laterally displaced femurs (thigh bone), and shallow abnormal acetabular fossae (hip sockets). Less frequent skeletal problems include lordosis, kyphosis and scoliosis (abnormal curvatures of the spine) as well as osteopenia (decreased bone mineral density) and degenerative hip disease. Many patients have required hip replacements.
Approximately 42% of individuals with SIOD have reduced thyroid function. However, to date, the poor thyroid function has not caused clinical symptoms (subclinical hypothyroidism). Among those who have received thyroid hormone supplementation, the correction of thyroid hormone levels does not mitigate other symptoms of SIOD.
All reported affected individuals have eventually developed renal dysfunction. The kidney disease is characterized by progressively worsening loss of protein in the urine and ultimately concludes with renal failure. The progressive renal disease is not responsive to immunosuppressant therapy. The diagnosis of renal dysfunction is usually made concurrent with or within the five years following the diagnosis of the growth failure.
Renal failure requiring dialysis or kidney transplantation usually develops within the subsequent 11 years, although the rate of progression varies greatly. Because renal disease causes high blood pressure and high levels of blood cholesterol and lipids, the theory is that it accentuates the vascular disease of SIOD; however, renal transplantation does not prevent progression of the atherosclerosis. The incidence of a single kidney may be higher than in the unaffected population and this is associated with a more rapid onset of renal failure.