Hypochondroplasia Research Paper

HYPOCHONDROPLASIA

Crystal Tucker
Developmental Disabilities
Friday, October 4, 2013

What is Hypochondroplasia

Hypochondroplasia, is an autosomal dominant disorder, which is caused by the mutation in the fibroblast growth factor receptor 3, also known as FGFR3, located on chromosome 4. It remains unclear at this time as to how these mutations lead to the features one inherits from having hypochondroplasia, there are researchers who believe that the cause may be due to these genetic changes causing the protein to be overly active, thus interfering with the skeletal development. This, in the end leads to the disturbances in bone growth which are the characteristics of this disorder. Individuals
If a child is born with 2 altered copies of the FGFR3 gene (meaning both parents are affected), they tend to have more severe problems with bone growth then a child would if it were born with just 1 FGFR3 mutation. However, a child can be born with hypochondroplasia to average size parents. This happens due to a new chance change (mutation), meaning that the risk of this happening again is virtually zero. Hypochondroplasia, is just one of many in a family of bone dysplasias which are caused by the same mutation in the FGFR3 gene. Some examples of other conditions in this family are, achondroplasia (which is the closest to hypochondroplasia but more severe), SADDAN syndrome, and thanatophoric dysplasia. Hypochondroplasia however, is known to be the mildest in this particular series of related conditions. Common features of one with hypochondroplasia are, short arms, short legs, broad, short hands and feet, large head, limited range of motion at the elbows, sway of the lower back, and bowed legs. It is estimated that 1 in every 15,000 to 40,000 newborns are born with hypochondroplasia each year, in the USA alone. This works out to only 0.01% of the population. One site reports that there are approximately 180,000 to 312,000 known live births, to
Special programing and teachers directed to an individual’s specific needs are available for those who require the assistance.

EARS & HEARING Many children with hypochondroplasia (unfortunately it is not known exactly how many at this point in time), will develop middle ear dysfunction. This can be recurrent and persistent and is accompanied by conductive hearing loss. If this is not treated right away it can lead to delays in one’s language and speech. A surgical incision into the eardrum, in order to relieve pressure or drain fluid (also known as myringotomy) can be performed, including tube placement. However, if a child is in need of ventilation tubes, they should be maintained until the age of 8 years.

LIMITED ELBOW EXTENSION The average person has an elbow extension of 150˚, for an individual with hypochondroplasia however, a limitation of 20˚ to 60˚ is common. This effects ones effective reach, making it difficult to perform certain tasks (e.g. for toileting). One with these limitations can use adaptive devices if necessary (e.g. bottom wiper for