Cystinuria gene 2

This gene is one of two genes involved in cystinuria.

Epidemiology

Cystinuria is not rare. The prevalence is 1:7.000

Gene Structure

The gene SLC7A9 formerly named b(0,+)AT is localized on chromosom 19 (19q13.1). It is about 40kb in size an consits of 13 exons, 12 of them translated.

Phenotype

The most important symptome is cystinuria. This leads to cysine stone formation because of the bad solubility of cystine in urinary environment. Later on in the history of the disease there might be recurrent urinary infections dominating the clinical picture. End stage renal failure is rare. According to the classical differention of cystinuria mutations in this small subunit may be classified as type 2 and 3 (ROSENBERG).

Pathology

The protein product of this gene is in its functional form highly glycosilated. It forms a heterodimer with a big subunit. This heterodimer is the transporter for dibasic amino acids. It can be found on the luminal membrane of enterocyzes and proximal tubulus cells. The resultant defect in transport refers not only to cystein but other dibasic amino acids lysine and arginine are effected too. But only the transport defect of cystine gains clinical importance.

Test Strategy

Confirmation of the diagnosis when cystinuria is suspected. Family screening if a patient in the family is known.

Interpretation

The importance of the genetic testing of this gne can be seen in family consuling and early prophylaxis.

Genetests:

Related Diseases:

Cystinuria
	SLC3A1
	SLC7A9

References:

1.	None (2004) The molecular basis of kidney stones.

2.	None (2004) The molecular basis of cystinuria.

3.	Dello Strologo L et al. (2006) Cystinuria.

4.	NCBI article NCBI 11136

5.	OMIM.ORG article Omim 604144

6.	Orphanet article Orphanet ID 119713

7.	Wikipedia article Wikipedia EN (SLC7A9)