Scientific background:

Summary: This gene is one of two genes involved in cystinuria.

Gene: The gene with the current short name SLC3A1 also known as rBAT. It is located on chromosome 2 (2 p16.3). Its size is about 45 kb and it consists of 10 Exons.

Pathology: Together with the small subunit the protein product of this gene forms a heterodimer which is involved in cystine and dibasic and neutral amino acid transport in proximal tubule and intestine. But only cystinuria gains clinical importance as a result of kidney stone formation.

Clinical signs: The symptomes of cystinuria are defined by the formation of cystein kidney stones. These stones show a glistening yellow color. When recognized early a prophylaxis is possible. Mutations of this great subunit of the amino acid transporter appear clinically as type I cystinuria according to ROSENBERG.

Epidemiology: The frequency is 1:7.000. This way cystinuria is one of the most frequent inherited diseases.

Interpretation: The finding of a relavant mutation confirms a clinical diagnosis.

Test strategy: The genetic test is provided for effective family couselling and confirmation of a clinical suspicion to provide an early prophylaxis.

Methodology:

	clinical test	Method		Genomic sequencing of the entire coding region
		Turn-around time		25 working days
		Effort		medium
		Specimen		DNA
		Quality assessment		Internal quality control only
	All known and new missense, nonsense and splice mutations can be detected.
	clinical test	Method		Carrier testing
		Turn-around time		5 working days
		Effort		little
		Specimen		DNA
		Quality assessment		Internal quality control only
	The test is only specific about the mutation already known in this kindred.
	research test	Method		Gene dosage measurements
		Turn-around time		25 working days
		Effort		medium
		Specimen		DNA
		Quality assessment		Internal quality control only
	Of the gene rearrangements, this method is useful to detect large deletions or duplications.

Literature: 

Langman CB et al. (2004) The molecular basis of kidney stones.
Goodyer P et al. (2004) The molecular basis of cystinuria.
Dello Strologo L et al. (2006) Cystinuria.