Diastrophic dysplasia
Encyclopedia
Diastrophic dysplasia is an autosomal recessive
dysplasia
which affects cartilage
and bone
development. ("Diastrophism" is a general word referring to a twisting.)
Affected individuals have short stature with very short arms and legs and joint problems that restrict mobility.
, tarsus valgus, and inversion adducted appearances. Furthermore they classically present with scoliosis (progressive curvature of the spine
, and unusually positioned thumbs (hitchhiker thumbs). About half of infants with diastrophic dysplasia are born with an opening in the roof of the mouth called a cleft palate. Swelling of the external ear
s is also common in newborns and can lead to thickened, deformed ears.
The signs and symptoms of diastrophic dysplasia are similar to those of another skeletal disorder called atelosteogenesis, type 2. Diastrophic dysplasia tends to be less severe, however.
Diastrophic dysplasia affects about 1 in 100,000 births. Mutation
s in the SLC26A2
gene
cause diastrophic dysplasia, and it is one of a spectrum of skeletal disorders caused by mutations in the SLC26A2 gene. The protein made by this gene is essential for the normal development of cartilage and for its conversion to bone. Cartilage is a tough, flexible tissue that makes up much of the skeleton
during early development. Most cartilage is later converted to bone, but in adulthood this tissue continues to cover and protect the ends of bones and is present in the nose and external ears. Mutations in the SLC26A2 gene alter the structure of developing cartilage, preventing bones from forming properly and resulting in the skeletal problems characteristic of diastrophic dysplasia.
This condition is an autosomal recessive disorder, which means the defective gene is located on an autosome
, and both parents must carry one copy of the defective gene in order to have a child born with the disorder. The parents of a child with an autosomal recessive disorder are usually not affected by the disorder.
The Little People of America
is an organization of people with all kinds of short-stature syndromes, family members and caregivers, dedicated to improving the quality of life of affected persons, and improving their integration into society.
Recessive
In genetics, the term "recessive gene" refers to an allele that causes a phenotype that is only seen in a homozygous genotype and never in a heterozygous genotype. Every person has two copies of every gene on autosomal chromosomes, one from mother and one from father...
dysplasia
Dysplasia
Dysplasia , is a term used in pathology to refer to an abnormality of development. This generally consists of an expansion of immature cells, with a corresponding decrease in the number and location of mature cells. Dysplasia is often indicative of an early neoplastic process...
which affects cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
and bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
development. ("Diastrophism" is a general word referring to a twisting.)
Affected individuals have short stature with very short arms and legs and joint problems that restrict mobility.
Symptoms
This condition is also characterized by an unusual clubfoot) with twisting of the metatarsals, inward- and downward-turning footFoot
The foot is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws...
, tarsus valgus, and inversion adducted appearances. Furthermore they classically present with scoliosis (progressive curvature of the spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
, and unusually positioned thumbs (hitchhiker thumbs). About half of infants with diastrophic dysplasia are born with an opening in the roof of the mouth called a cleft palate. Swelling of the external ear
Ear
The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....
s is also common in newborns and can lead to thickened, deformed ears.
The signs and symptoms of diastrophic dysplasia are similar to those of another skeletal disorder called atelosteogenesis, type 2. Diastrophic dysplasia tends to be less severe, however.
Genetic prevalence
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
s in the SLC26A2
SLC26A2
The SLC26A2 protein is a member of the solute carrier family. In humans, this transporter is encoded by the SLC26A2 gene.- Function :The diastrophic dysplasia sulfate transporter is a transmembrane glycoprotein implicated in the pathogenesis of several human chondrodysplasias...
gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
cause diastrophic dysplasia, and it is one of a spectrum of skeletal disorders caused by mutations in the SLC26A2 gene. The protein made by this gene is essential for the normal development of cartilage and for its conversion to bone. Cartilage is a tough, flexible tissue that makes up much of the skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
during early development. Most cartilage is later converted to bone, but in adulthood this tissue continues to cover and protect the ends of bones and is present in the nose and external ears. Mutations in the SLC26A2 gene alter the structure of developing cartilage, preventing bones from forming properly and resulting in the skeletal problems characteristic of diastrophic dysplasia.
This condition is an autosomal recessive disorder, which means the defective gene is located on an autosome
Autosome
An autosome is a chromosome that is not a sex chromosome, or allosome; that is to say, there is an equal number of copies of the chromosome in males and females. For example, in humans, there are 22 pairs of autosomes. In addition to autosomes, there are sex chromosomes, to be specific: X and Y...
, and both parents must carry one copy of the defective gene in order to have a child born with the disorder. The parents of a child with an autosomal recessive disorder are usually not affected by the disorder.
See also
Matt Roloff, a businessman and motivational speaker, has diastrophic dysplasia dwarfism. He is a vocal proponent of research and understanding of the disorder, as well as the assimilation of fellow sufferers into everyday lifeThe Little People of America
Little People of America
Little People of America is a non-profit organization which provides support, resources and information to individuals with dwarfism and their families...
is an organization of people with all kinds of short-stature syndromes, family members and caregivers, dedicated to improving the quality of life of affected persons, and improving their integration into society.