Scientific background:

Summary: Microdeletion in this gene have been identified to cause Pseudohypoparathyroidism type IB by impaired impriting of the promotor region of the GNAS1 gene.

Gene: The gene spans about 30kb. Two splice variant with 9 and 8 translated exons are indentified.

Methodology:

	clinical test	Method		Genomic sequencing of the entire coding region
		Turn-around time		25 working days
		Effort		little
		Specimen		DNA
		Quality assessment		Internal quality control only
	All known and new missense, nonsense and splice mutations can be detected.
	clinical test	Method		Multiplex Ligation-Dependent Probe Amplification
		Turn-around time		25 working days
		Effort		little
		Specimen		DNA
		Quality assessment		Internal quality control only
	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.

Literature: 

Jüppner H et al. (2006) Autosomal-dominant pseudohypoparathyroidism type Ib is caused by different microdeletions within or upstream of the GNAS locus.
Jüppner H et al. (2006) Different mutations within or upstream of the GNAS locus cause distinct forms of pseudohypoparathyroidism.
Linglart A et al. (2005) A novel STX16 deletion in autosomal dominant pseudohypoparathyroidism type Ib redefines the boundaries of a cis-acting imprinting control element of GNAS.
Laspa E et al. (2004) Phenotypic and molecular genetic aspects of pseudohypoparathyroidism type Ib in a Greek kindred: evidence for enhanced uric acid excretion due to parathyroid hormone resistance.
Liu J et al. (2005) Distinct patterns of abnormal GNAS imprinting in familial and sporadic pseudohypoparathyroidism type IB.
Bastepe M et al. (2003) Autosomal dominant pseudohypoparathyroidism type Ib is associated with a heterozygous microdeletion that likely disrupts a putative imprinting control element of GNAS.
Bastepe M et al. (1999) Two frequent tetra-nucleotide repeat polymorphisms between VAPB and STX16 on chromosome 20q13.