Cystine disease

Cystine disease is a lysosomal storage disease, due to the short arm of chromosome 17 of 13 positions (17p13) number of boxes gene defect causes the cysteine ​​(cystine) to carry out the transport of lysosomal unitary Each (transporter) dysfunction, making cystine accumulation in the cell lysosomes, and thus resulting in tissue and organ lesions.
DirectoryThe incidence of type inheritance pattern characterized by growth retardation clinical situation occurs other diagnostic treatment and prognosisType according to time of onset and severity of the disease can be divided into three types: one, nephropathy type / infantile (nephrotic cystinosis); Second, intermediate / juvenile (intermediate cystinosis); Third, non-nephrotic type / adult (non-nephrotic cystinosis ). Among nephropathy type / infantile most common symptoms are most severe.The incidence of disease incidence has been estimated as 1/200000. Bretagne region in France (Brittany), the study found the incidence of the disease in the region 1 / 26,000.Currently this disease has been listed as China's announcement of rare diseases, it is estimated that the incidence of Taiwan should be one ten thousandth or less.Mode of inheritance is autosomal recessive disease, which means that the parents of each gene with a mutation, regardless of gender will be the next generation of tires every chance of suffering from this disease a quarter.Clinical manifestations nephropathy type / infantile patients are usually asymptomatic newborn first few months, but in the 6-9 months old when that is gradually emerging anorexia, vomiting, polyuria, growth retardation situation, and the emergence of kidneys and other organs of the lesion . The main clinical manifestations are renal Fanconi syndrome.Fanconi syndrome (renal Fanconi syndrome):Often occurs in June a large, tubular unable to due to water, electrolytes, bicarbonate, phosphate, calcium, carnitine, molecules such as glucose and amino acid reabsorption, and the emergence polyuria, polydipsia, dehydration Even acidosis symptoms.Electrolytes and amino acids and other molecules loss would patients with a variety of ailments, including: (1) low-phosphate rickets, often causing the patient's pain when walking. (2) low blood calcium, causing limbs twitching, severe low will hinder the heart's normal conduction. (3) occasionally hyponatremia and hypomagnesemia from happening. (4) will be higher than the actual age of bone behind.Due to the gradual glomerular damage, poor growth and severe renal glomerular filtration rate decreased, 10-year-old kidney failure that may occur.Corneal cystine crystals (cornea) cystine crystals:Patients often appear in the 2-3 age symptoms of photophobia, after corneal examination, can be found in the cornea of ​​the eye cystine crystals (corneal crystals) can occur before age 1. Untreated nephropathy in patients with type often after 16 months old can be found in this characterization.Also often appear retinopathy (peripheral retinal lesions), repeated corneal injury (recurring) corneal erosion, low visual acuity change characterization. Some childhood eye disease that occurs in patients even lead to blindness.Growth retardation is usually found at six months oldA situation occurs that may arise hypothyroidism, pituitary gonadal function and insulin secretion disorders.Other normal intelligence, but may occur late in the disease and brain atrophy neurological lesions.Intermediate / juvenile relatively mild symptoms of kidney disease, occurrence time is late, usually in the 6-8 age of onset.Non nephropathy type / adult symptoms of this type for the eyes and bone marrow have cystine crystals, usually only appear photophobia symptoms.Diagnosis may use cysteine ​​protein binding technique (cystine binding protein assay) to detect blood leukocyte cystine (cystine) concentration; nephropathy type / infantile often normal value 50-100 times. This detection technology can also be used to detect fibrous tissue, conjunctival tissue and muscle intracellular homocysteine ​​levels. The first three months of pregnancy can also be from the skin, the cultured amniotic fluid cells or chorionic fibrous tissue cells for prenatal diagnosis.Treatment study found that homocysteine ​​(cysteamine tartaric acid, medicines called Cystagon) drug treatment, the preferred treatment for the disease cystine way, this a free state thiols, cystine structures can be dissolved from more than 90% of the cystine cells, will be able to effectively control the renal disease progression in patients with variant.Long-term active treatment can avoid or delay kidney failure, and the incidence of hypothyroidism, and can dissolve the cystine accumulation in muscle tissue to relieve symptoms and improve patient growth situation.Diagnosis, provide treatment as soon as possible; within one month after birth if that is underway, the treatment can often get the best results, and helps the growth of kidney and avoid deterioration of renal function. Found that long-term treatment, although they can not cure the disease, but can be avoided in patients with significant late complications.Side effects that may occur in nausea and vomiting, but may be due to drugs with unpleasant odors caused with taste; recent research suggests can be used with gastrointestinal medication ─ omeprazole, in order to improve on the stomach discomfort.It must be noted that, oral medications cysteine, are not intended to improve corneal cystine crystals, it is recommended that patients using cysteamine hydrobromide (cysteamine hydrochloride) eye drops, to within a few months to reduce corneal cystine crystals, a few weeks reduce eye sensitivity to light, dark or while wearing sunglasses, but also to reduce the sunlight brought photophobia situation.The main treatment goals for replenish electrolytes caused by kidney disease, loss of amino acids and other substances, including water, sodium, potassium, phosphorus, calcium, magnesium, vitamin Ḏ ... etc., the amount of intake required under depending on the patient's condition and the body should be regularly monitored in order to achieve the desired.In case of hypothyroidism, pituitary gonadal function problems such as endocrine disorders may accept the associated endocrine therapy.When the progressive deterioration of renal function outcome to renal failure, patients are usually required to undergo blood or peritoneal dialysis treatment, and may need to consider a kidney transplant. After kidney transplantation, even cystine crystals deposited in the kidney transplant, but still does not produce Fanconi syndrome may occur more frequently after transplantation rejection situations, patients need to track return visits regularly to provide immediate treatment