Achondroplasia / Hypochondroplasia

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Achondroplasia is a genetic disorder that results in dwarfism. The word achondroplasia literally means “without cartilage formation.” Cartilage is a tough but flexible tissue that makes up much of the skeleton during early development. However, in achondroplasia the problem is not in forming cartilage but in converting it to bone (a process called ossification), particularly in the long bones of the arms and legs. Achondroplasia is similar to another skeletal disorder called hypochondroplasia, but the features of achondroplasia tend to be more severe.

In people with achondroplasia arms and legs are short, while the trunk is usually of normal length. They have short fingers and an enlarged head with a prominent forehead. Their intelligence is generally not affected.

The disease is caused by mutations in the FGFR3 gene (Fibroblast Growth Factor Receptor 3) and is inherited in an autosomal dominant pattern. Approximately 99% of patients with achondroplasia harbor the same mutation (G380R) in FGFR3 gene. Hypochondroplasia is also caused by mutations in FGFR3 gene.

Method

Molecular analysis for achondroplasia is carried out using ARMS-PCR for the detection of the G380R mutation in FGFR3 gene.

Complete analysis of FGFR3 gene (coding exons and adjascent intron-exon boundaries) using bidirectional Sanger sequencing is performed for the detection of all possible mutations that could lead to the development of hypochondroplasia.

Sample type: Peripheral blood in EDTA

Time to result: 1 week for G380R mutation and 2 weeks for FGFR3 gene sequencing

There is the possibility of prenatal diagnosis for achondroplasia or hypochondroplasia in chorionic villi or amniotic fluid samples.