Hyperoxaluria is an excessive urinary excretion of oxalate. Individuals with hyperoxaluria often have calcium oxalate kidney stones. It is sometimes called Birds disease, after Golding Bird, who first described the condition. Causes
Hyperoxaluria can be primary (as a result of a genetic defect) or secondary to another disease process. Type I primary hyperoxaluria (PH1) is associated mutations in the gene encoding AGXT, a key enzyme involved in oxalate metabolism. PH1 is an example of a protein mistargeting disease, wherein AGXT shows a trafficking defect. Instead of being trafficked to peroxisomes, it is targeted to mitochondria, where it is metabolically deficient despite being catalytically active. Type II is associated with GRHPR.Secondary hyperoxaluria can occur as a complication of jejunoileal bypass, or in a patient who has lost much of the ileum with an intact colon. In these cases, hyperoxaluria is caused by excessive gastrointestinal oxalate absorption.Excessive intake of oxalate-containing food, such as rhubarb, may also be a cause in rare cases. Diagnosis
Types
Primary hyperoxaluria
Enteric hyperoxaluria
Idiopathic hyperoxaluria
Oxalate poisoning

Treatment
The main therapeutic approach to primary hyperoxaluria is still restricted to symptomatic treatment, i.e. kidney transplantation once the disease has already reached mature or terminal stages. However, through genomics and proteomics approaches, efforts are currently being made to elucidate the kinetics of AGXT folding which has a direct bearing on its targeting to appropriate subcellular localization. Secondary hyperoxaluria is much more common than primary hyperoxaluria, and should be treated by limiting dietary oxalate and providing calcium supplementation. A child with primary hyperoxaluria was treated with a liver and kidney transplant.
Deletions and mutations in the NSD1 gene is a common cause for patients with Sotos syndrome and in some cases for Weaver syndrome as well.Features distinguishing Weaver syndrome from Sotos syndrome include broad forehead and face, ocular hypertelorism, prominent wide philtrum, micrognathia, deep-set nails, retrognathia with a prominent chin crease, increased prenatal growth, and a carpal bone age that is greatly advanced compared to metacarpal and phalangeal bone age. Treatment
There is no cure available for Weaver syndrome. However, with multidisciplinary management such as neurological, pediatric, orthopedic and psychomotor care and genetic counseling, symptoms can be managed. Surgery may be used to correct any skeletal issues. Physical and occupational therapy are considered an option to help with muscle tone. Also, speech therapy is often recommended for speech related problems. Prognosis
With appropriate treatment and management, patients with Weaver syndrome appear to do well, both physically and intellectually, throughout their life and have a normal lifespan. Their adult height can reach 7-8 feet. Epidemiology
The incidence of Weaver syndrome is uncertain, as the causative mutation was only identified in 2011. As of December 2013, 48 cases of Weaver syndrome had been documented and confirmed. In 2012, the South West Thames Regional Genetic Service at St Georges Hospital in London, based on their detection rate among a cohort of patients within their Childhood Overgrowth Study, estimated a prevalence rate similar to that of Sotos syndrome, around 1 in 15,000. History
The condition was first described by American physician David Weaver in 1974. See also
Beckwith–Wiedemann syndrome
Perlman syndrome
Sotos syndrome

References


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