Achondrogenesis is a group of severe disorders that affect cartilage and bone development. These conditions are characterized by a small body, short limbs, and other skeletal abnormalities.
The genetic alterations in achondrogenesis affect the Golgi apparatus. It leads to the lack of protein transmission to the growth hormones. Therefore the growth of bone and cartilage is disturbed, leading to short limbs, a narrow chest, underdeveloped lungs, and a lack of bone development in the spine and pelvis.
Achondrogenesis type IA is caused by mutations in the TRIP11 gene. Achondrogenesis type IB is caused by mutations in the SLC26A2 gene. These two genes are required for the efficient cellular transport of certain cartilage proteins needed to build skeleton and other tissues.
Hypochrondroplasia is a genetic disorder characterized by small stature and disproportionately short arms, legs, hands, and feet (short-limbed dwarfism). Short stature often is not recognized until early to mid childhood or, in some cases, as late as adulthood.
Phocomelia is a rare condition that affects babies at birth. This condition causes the upper or lower limbs of the child to be underdeveloped or missing. Phocomelia can affect one or multiple limbs. This condition can be caused by a genetic syndrome or from exposure to a specific drug during pregnancy.
Noonan syndrome is a genetic disorder that prevents normal development in various parts of the body. A person can be affected by Noonan syndrome in a wide variety of ways. These include unusual facial characteristics, short stature, heart defects, other physical problems and possible developmental delays.
These conditions are characterized by a small body, short limbs, and other skeletal abnormalities. As a result of serious health problems, infants with achondrogenesis usually die before birth, are stillborn, or die soon after birth from respiratory failure.
Two specific mutations in the FGFR3 gene are responsible for almost all cases of achondroplasia. Researchers believe that these mutations cause the FGFR3 protein to be overly active, which interferes with skeletal development and leads to the disturbances in bone growth seen with this disorder.
Mutations in the HYAL2 gene responsible for CLP
The HYAL2 gene encodes hyaluronidase 2, an enzyme responsible for degrading hyaluronan (also known as hyaluronic acid). Hyaluronan is a carbohydrate polymer usually found in connective tissue and the hard palate.
We have two copies of most of our genes, one from each parent. People with osteopetrosis have a gene that causes the body to make too few or abnormal cells called osteoclasts. When the osteoclasts are missing, old bone is not broken down as new bone is made, leading to dense, weak bones.
All types of primordial dwarfism are caused by changes in genes. Different gene mutations cause the different conditions that make up primordial dwarfism. In many cases, but not all, individuals with primordial dwarfism inherit a mutant gene from each parent. This is called an autosomal recessive condition.
Frequency. Leigh syndrome affects at least 1 in 40,000 newborns. The condition is more common in certain populations. For example, the condition occurs in approximately 1 in 2,000 newborns in the Saguenay Lac-Saint-Jean region of Quebec, Canada and in approximately 1 in 1,700 individuals on the Faroe Islands.
Type 1A and 1B Achondrogenesis are both inherited in an autosomal recessive pattern. Type 1A is caused by genetic changes in the TRIP11 gene.
Collapse Section. Cherubism is a disorder characterized by abnormal bone tissue in the jaw. Beginning in early childhood, both the lower jaw (the mandible) and the upper jaw (the maxilla) become enlarged as bone is replaced with painless, cyst-like growths.
Kniest syndrome is a genetic disorder stemming from a type 2 collagen defect (COL2A1) passed on autosomal dominant (one parent passes on the disorder). It affects the cartilage, making it soft and crumbly with a Swiss cheese appearance.
Achondroplasia appears to affect males and females in equal numbers. This disorder begins in the developing fetus and is one of the most common forms of skeletal dysplasia that causes dwarfism. The estimated frequency of achondroplasia has ranged from about one in 15,000 to one in 35,000 births.
If one parent has achondroplasia, the infant has a 50% chance of inheriting the disorder. If both parents have the condition, the infant's chances of being affected increase to 75%. However, most cases (about 80%) appear as spontaneous mutations.
All people who have only a single copy of the normal FGFR3 gene and a single copy of the FGFR3 gene mutation have achondroplasia. Most people who have achondroplasia have average-size parents. In this situation, the FGFR3 gene mutation occurs in one parent's egg or sperm cell before conception.
The majority of people living with achondroplasia have a normal life span and normal intelligence, regardless of delayed development in infancy. Though complications from achondroplasia are a possibility, taking care of symptoms can help prevent serious health problems from occurring later in life.
According to the NHGRI , most people with achondroplasia have a normal life span. However, there's a slightly increased risk of death during the first year of life. There may also be an increased risk of heart disease later in life.
Definition. The presence of abnormally small extremities. [ from HPO]
Williams Syndrome (WS) is a rare genetic disorder characterized by mild to moderate delays in cognitive development or learning difficulties, a distinctive facial appearance, and a unique personality that combines over-friendliness and high levels of empathy with anxiety.
Disease definition. Short stature-webbed neck-heart disease syndrome is characterized by short stature, intellectual deficit, facial dysmorphism, short webbed neck, skin changes and congenital heart defects. It has been reported in four Arab Bedouin sibs born to consanguineous parents.
Russell-Silver syndrome is a growth disorder characterized by slow growth before and after birth. Babies with this condition have a low birth weight and often fail to grow and gain weight at the expected rate (failure to thrive).