What chromosome is affected in achondroplasia?
Although this condition can be inherited in an autosomal dominant manner, 80% of cases are due to new, sporadic mutations. Mutations involve the gene encoding fibroblast growth factor receptor 3 (FGFR3), situated on chromosome 4.
What chromosome is FGFR3 on?
FGFR3, a tyrosine kinase receptor gene, is located at chromosome 4p16. 3 and is composed of 19 exons [14]. The extracellular portion can bind with fibroblast growth factors, initiating cascades of downstream signals that ultimately influence cell growth, migration, angiogenesis, and differentiation [14].
What type of DNA mutation causes achondroplasia?
What is achondroplasia? Achondroplasia is caused by a gene alteration (mutation) in the FGFR3 gene. The FGFR3 gene makes a protein called fibroblast growth factor receptor 3 that is involved in converting cartilage to bone. FGFR3 is the only gene known to be associated with achondroplasia.
What does achondroplasia cause?
Achondroplasia is a bone growth disorder that causes disproportionate dwarfism. Dwarfism is defined as a condition of short stature as an adult. People with achondroplasia are short in stature with a normal sized torso and short limbs. It’s the most common type of disproportionate dwarfism.
Is dwarfism a gene or chromosomal mutation?
Dwarfism is usually the result of a genetic mutation. But having a gene or genes responsible for dwarfism can occur in a couple of ways. In some cases, it can happen spontaneously. You may not be born with mutated genes inherited from a parent.
Is achondroplasia a substitution mutation?
Virtually all cases of achondroplasia are caused by a single nucleotide substitution in the FGFR3 gene, which alters one amino acid in the FGR3 protein (Gly380Arg). Other mutations in this gene cause other skeletal disorders in humans. Very few genetic disorders are as mutation-specific as in achondroplasia.
What are the genotypes and phenotypes of achondroplasia?
In the case of achondroplasia, the homozygous dominant genotype results in a lethal phenotype. These fetuses are stillborn or die shortly after birth. The phenotype is determined by a dominant allele that interferes with bone growth during development.
Is achondroplasia homozygous or heterozygous?
Achondroplasia is an autosomal dominant condition and has three main forms. The lethal homozygous form, the non-lethal heterozygous form and the third in which the achondroplasia is severe and is associated with developmental delay and acanthosis nigricans (SADDAN).
How does achondroplasia affect the skeletal system?
Achondroplasia is the most common form of skeletal dysplasia, occurring in about one in every 40,000 births. Achondroplasia impairs the growth of bone in the limbs and causes abnormal growth in the spine and skull.
