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GENATLAS PHENOTYPE

last update : 09-01-2009

Symbol	BLOD
Location	3p21.3
Name	Blomstrand chondrodysplasia, lethal dwarfism
Corresponding gene	PTH1R
Other symbol(s)	BOCD
Main clinical features	advanced endochondral bone formation and increased bone density short limbs, polyhydramnios, hydrops fetalis, facial anomalies, preductal aortic coarctation, and remarkably advanced skeletal maturation, epiphyseal cartilage markedly reduced with fusoform and occasionally vacuolated chondrocytes; the epiphyseal-metaphyseal junction was wide and irregular; the zone of proliferating cartilage was narrow, but also irregular, bone remodeling was deficient, and the osteoclasts were rare
Genetic determination	autosomal recessive
Function/system disorder	osteo-articular
Type	disease

Gene product

Name	parathyroid hormone related peptide receptor (PTHR1)

Mechanism(s)

Gene mutation	Chromosome rearrangement	Effect	Comments
nonsense		truncated protein	nonsense mutation (R104X)in type 1

Remark(s)

Genotype/Phenotype correlations

type I is caused by a complete inactivation of the PTHR1 whereas low levels of residual activity due to a near complete inactivation of the PTHR1 result in the relatively milder presentation of type II