The LMX1B gene plays a central role in limb dorsoventral patterning, and also patterning of the nails, patella, and long bones during development. Human fetal and adult kidneys show a high level of LMX1B expression thereby suggesting a critical function for this gene during kidney development. A 24-hour urine collection will quantitate protein and creatinine excretion. Radiography will reveal iliac horns and hypoplastic patella in adults. Conduct a MRI to identify abnormal muscle insertions, which radiography cannot.
Sonography better evaluates the unossified patella in young children.
Electron microscopy can detect ultra-structural changes such as irregularities and thickening of the basement membrane, which cannot be seen with light microscopy. This moth-eaten appearance is pathognomonic. A typical lesion consists of irregular basement membrane thickening, epithelial foot process fusion, and the presence of fibrillar collagen-like material within the basement. Unless the patient presents with acute findings, perform the evaluation on an outpatient basis. Suggest knee replacement if the patient develops osteoarthritis in the knees.