Oculocerebrorenal syndrome
Encyclopedia
Oculocerebrorenal syndrome (also called Lowe syndrome) is a X-linked recessive disorder characterized by hydrophthalmia, cataract
s, intellectual disabilities, aminoaciduria
, reduced renal ammonia
production and vitamin D-resistant rickets
.
Lowe syndrome can be considered a cause of Fanconi syndrome
.
Lowe Syndrome (LS) is a rare genetic condition that causes physical and mental handicaps, and medical problems.
The condition became known as "Lowe syndrome" named after Dr. Charles Lowe, the senior member of the group that described it. Because of the three major organ systems involved (eyes, brain, and kidney), it is also known as OCRL (oculo-cerebro-renal) syndrome.
While not present at birth, many Lowe Syndrome boys develop kidney problems at approximately one year of age. This is characterized by the abnormal loss of certain substances into the urine, including bicarbonate, sodium, potassium, amino acids, organic acids, albumin and other small proteins, calcium, phosphate, glucose, and L-carnitine. This problem is known as Fanconi-type renal tubular dysfunction and can also be seen in certain other diseases and syndromes. In Lowe syndrome, the Fanconi syndrome may be mild and involve only a few substances or may be severe and involve large losses of many substances. Medications can be prescribed to replace the lost substances.
1. Because of this defective gene, an essential enzyme called PIP2-5-phosphatase is not produced. This is the underlying cause of Lowe syndrome.
The gene has been mapped and the deficient enzyme has been identified, although its role is not fully understood. Today there is no correlation between the gene mutation, the level of enzyme deficienty and the symptoms. Other Syndromes such as Dents, may have almost identical mutations but while exhibiting some symptoms such as kidney disorders, do not have the enzyme deficiency or other symptoms such as cataracts.
Much research has taken place in the last few years, but the diagnosis is still largely clinical, based on cataracts at birth in both eyes and a kidney disorder, plus a positive test for the enzyme deficiency.
Cataract
A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...
s, intellectual disabilities, aminoaciduria
Aminoaciduria
Aminoaciduria is the presence of amino acids in the urine. Small amounts of amino acids are also present in normal urine. Increased total urine amino acids may result from metabolic disorders, chronic liver disease or renal disorders. Aminoacidurias can be divided into primary and secondary...
, reduced renal ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
production and vitamin D-resistant rickets
Rickets
Rickets is a softening of bones in children due to deficiency or impaired metabolism of vitamin D, magnesium , phosphorus or calcium, potentially leading to fractures and deformity. Rickets is among the most frequent childhood diseases in many developing countries...
.
Lowe syndrome can be considered a cause of Fanconi syndrome
Fanconi syndrome
Falconi syndrome is a disease of the proximal renal tubules of the kidney in which glucose, amino acids, uric acid, phosphate and bicarbonate are passed into the urine, instead of being reabsorbed. Fanconi syndrome affects the proximal tubule, which is the first part of the tubule to process fluid...
.
Lowe Syndrome (LS) is a rare genetic condition that causes physical and mental handicaps, and medical problems.
History
It was first described in 1952 by Drs. Lowe, Terrey, and MacLachlan at the Massachusetts General Hospital in Boston.The condition became known as "Lowe syndrome" named after Dr. Charles Lowe, the senior member of the group that described it. Because of the three major organ systems involved (eyes, brain, and kidney), it is also known as OCRL (oculo-cerebro-renal) syndrome.
Presentation
Boys with Lowe Syndrome are born with cataracts in both eyes, which are usually removed at a few months of age. Most boys are fitted with glasses, contact lenses, or a combination of the two. Glaucoma is present in about 50% of the boys with Lowe syndrome, though usually not at birth. Prescription eye drop and/or surgery is required to maintain appropriate eye pressure in these cases.While not present at birth, many Lowe Syndrome boys develop kidney problems at approximately one year of age. This is characterized by the abnormal loss of certain substances into the urine, including bicarbonate, sodium, potassium, amino acids, organic acids, albumin and other small proteins, calcium, phosphate, glucose, and L-carnitine. This problem is known as Fanconi-type renal tubular dysfunction and can also be seen in certain other diseases and syndromes. In Lowe syndrome, the Fanconi syndrome may be mild and involve only a few substances or may be severe and involve large losses of many substances. Medications can be prescribed to replace the lost substances.
Cause
Lowe syndrome is a "genetic" condition (i.e. occurs from birth, due to a gene mutation that may not have any family history, or may be hereditary) and affects mainly males. It is caused by a single defective gene (an alteration or "mutation") in a gene called OCRLOCRL
Inositol polyphosphate 5-phosphatase OCRL-1 also known as Lowe oculocerebrorenal syndrome protein is an enzyme that in humans is encoded by the OCRL gene located on the X chromosome....
1. Because of this defective gene, an essential enzyme called PIP2-5-phosphatase is not produced. This is the underlying cause of Lowe syndrome.
The gene has been mapped and the deficient enzyme has been identified, although its role is not fully understood. Today there is no correlation between the gene mutation, the level of enzyme deficienty and the symptoms. Other Syndromes such as Dents, may have almost identical mutations but while exhibiting some symptoms such as kidney disorders, do not have the enzyme deficiency or other symptoms such as cataracts.
Much research has taken place in the last few years, but the diagnosis is still largely clinical, based on cataracts at birth in both eyes and a kidney disorder, plus a positive test for the enzyme deficiency.