Laboratory Studies
Laboratory findings associated with Lowe syndrome, also called oculocerebrorenal syndrome (OCRS) and oculocerebrorenal syndrome of Lowe (OCRL), are listed below.
Serum, as follows:
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Elevated serum enzyme levels
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Enzyme test (phosphatidylinositol-4,5-bisphosphate phosphatase; >99% sensitivity) in males who are affected
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Mild elevations of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK)
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Increased serum glutamic-oxaloacetic transaminase (SGOT) and lactate dehydrogenase (LDH)
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Serum protein electrophoresis shows a markedly elevated alpha-2-band, and total serum protein concentration is elevated frequently in patients older than 4 years.
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Acid phosphatase is elevated in most patients.
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Increased alkaline phosphatase levels
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Increased creatinine levels
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Hypokalemia
Urinalysis, as follows:
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Check for reducing substances
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Low urine osmolality and elevated 24-hour volumes
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Proteinuria
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Aminoaciduria
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Hyperphosphaturia, frequently present, but may be variable
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Calciuria
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Check urine ph
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Check L-carnitine (may be lost in urine)
Blood gas - Metabolic acidosis secondary to urinary loss of bicarbonate
Imaging Studies
Ocular ultrasound: B-scan is indicated if posterior pole cannot be visualized secondary to the cataract.
Ultrasound biomicroscopy of the anterior segment and anterior segment optical coherence tomography (AS-OCT) are helpful in determining the mechanism of glaucoma. [16, 17]
Cranial MRI: Mild ventriculomegaly is evident in about one third of patients. Additionally, in a periventricular and centrum semiovale distribution, increased signal intensity may occur on T2-weighted scans. These areas correspond to cysts of variable size and number and are yet of no known clinical significance.
Proton magnetic resonance spectroscopy exhibits findings consistent with gliosis, such as a prominent myoinositol peak. However, whether the increased signal is due to gliosis or buildup of phosphatidylinositol (4,5) biphosphate cannot be determined. [7, 18, 16, 19]
Other Tests
Ocular evaluation to assess possible carrier status: Slit lamp examination of the biological mother's lenses or females at risk to assess if any lenticular opacities
DNA testing: DNA carrier testing for familial mutation (requires prior identification of unique mutation of OCRL1 gene in that family); OCRL1 gene mutation analysis (approximately 90% sensitivity for males who are affected)
Histologic Findings
Renal histology usually is normal in utero and in neonates. However, within the first few months of life, these infants may show tubular abnormalities with dilation, atrophy, and accumulation of proteinaceous material in the tubular lumens. Young infants usually have normal glomeruli, but, after a few years, they may manifest glomerular lesions with sclerosis, focal fibrosis, and thickening of basement membranes.
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Classic lenticular opacities in a female carrier for Lowe syndrome. Note the punctate cortical opacities in radical wedges. Image courtesy of Otis Paul, MD.
