Dwarfism is the term applied when the patient’s height is far less than normal for his age and sex. The generally accepted definition is a height less than 147 cm or 4 feet 10 inches.
Most of these people have an average life expectancy and remain productive.
The reported incidence is 1 per 25,000 births.
Types of Dwarfism
Proportionate dwarfism
In this type of dwarfism, the head, trunk, and limbs are all proportionate to each other, but much smaller than the average.
An example would be hormonal deficiency where all the parts are stunted proportionally.
Disproportionate dwarfism
The most common type of dwarfism where the body parts that are not in proportion. to each other.
For example, achondroplasia results in shorter limbs but the trunk is relatively unaffected.
Causes of Dwarfism
Often the dwarfism results from a genetic mutation.
It could be a spontaeous mutation or inherited from affected/carrier parent
Both dominant and recessive transmission patterns are known.
Apart from mutation malnutrition or hormone deficiency could lead to short stature.
There are over 200 different conditions associated with dwarfism. Following are the common ones.
- Achondrogenesis-Disorders affecting cartilage and bone development
- Achondroplasia, Pseudoachondroplasia, and hypochondroplasia- Growth plate disorders
- Acrodysostosis – Rare genetic disorder leading to dysplasia and short stature
- Skeletal Dysplasias – heritable disorders of cartilage and bone growth
- Acromesomelic Dysplasia
- Diastrophic Dysplasia
- Chondrodysplasia Punctata
- Ellis Van-Creveld Syndrome
- Kneist Dysplasia
- Langer Mesomelic Dysplasia
- Metaphyseal Chondrodysplasiam[Schmid and McKusick Type]
- Multiple Epiphyseal Dysplasia
- Léri-Weill Dyschondrosteosis
- Spondyloepiphyseal Dysplasia congenita (SEDc)
- Spondyloepimetaphyseal Dysplasia (SEMD)
- Spondyloperiphereal Dysplasia
- Thanatophoric Dysplasia
- Morquio Syndrome
- Osteogenesis Imperfecta
- Primordial Dwarfism- results in a smaller body size
- Russel-Silver Syndrome
- Microcephalic Osteodysplastic Primordial Dwarfism Type I/III
- Microcephalic Osteodysplastic Primordial Dwarfism Type II
- Seckel Syndrome
- Meier-Gorlin Syndrome
- Turner Syndrome
Brief on different terms used in relation to dwarfism
Location
- Rhizomelic – root, i.e., bones of the upper arm or thigh
- Mesomelic – middle, i.e., bones of the forearm or lower leg
- Acromelic – end, i.e., bones of hands and feet.
- Micromelic – entire limbs are shortened
Source of the problem
- Chondro- of cartilage
- Osteo – of bone
- Spondylo- of the vertebrae
- Plasia- form
- Trophy- growth
Brief about Important Conditions Causing Dwarfism
Achondroplasia
Achondroplasia is the most common cause of dwarfism. It is a genetic disorder that occurs in one out of 25,000 to 40,000 babies. It is inherited as an autosomal dominant trait.
The condition is evident at birth. The affected persons have a long trunk and shortened upper parts of their upper limbs and lower limbs.
In achondroplasia, there is a process does not happen as effectively.
Other features are
- a large head with a prominent forehead
- a flattened bridge of the nose
- protruding jaw
- crowded teeth
- spine curvature abnormalities
Read more about Achondroplasia.
Spondyloepiphyseal Dysplasia Congenita
It is a genetic mutation that growth problems in the spine, and limbs.
The affected persons are dwarf and have the following problems
- Spine deformities
- Foot deformities such as club foot
- Cleft palate
- Joint diseases
- Degenerative changes in hip
- barrel-chested appearance
- Flattened facial bones
It affects approximately one in 95,000 babies.
Read about Spondyloepihyseal dysplasia congenita
Diastrophic Dysplasia
It is a rare form of dwarfism, diastrophic dysplasia occurs in about one in 100,000 births. The affected persons have shortened forearms and calves ( mesomelic shortening).
Other signs can include
- Deformed hands and feet
- Limited range of motion
- Cleft palate
- Cauliflower ears
- Scoliosis
- Clubfoot
Few children die of respiratory problems.
Turner syndrome
These children are predominantly girls. They have agenesis of their gonads. The chromosomal pattern is 45+XO. They have a characteristically short webbed neck, low hairline, square and shield-like chest, cubitus valgus and mental retardation. Although short, they grow at the rate of 4 cm each year with normal bone age and dental age but absent pubertal growth spurt, so that during adolescence, the skeletal age is delayed due to the absence of sex hormones (streak ovaries).
Other Causes of Dwarfism
- Growth hormone deficiency
- Hypothyroidism
- Intrauterine growth retardation
- Constitutional delayed growth and puberty
- Hypopituitarism
- Malnutrition
Appearance of the newborn at birth may lead to the diagnosis. Physical examination and x-rays would confirm the diagnosis.
Prenatal diagnosis can be attempted by ultrasound. If suspected or high risk [dwarf parents] amniocentesis can be done
Genetic testing may distinguish between causes of dwarfism. A diagnosis of achondroplasia, diastrophic dysplasia, or spondyloepiphyseal dysplasia can be confirmed through genetic testing. It can be done as part of prenatal
Sometimes dwarfism develop later in a child’s life. Following signs can indicate potential dwarfism.
- a larger head
- late development of certain motor skills [sitting up or walking]
- breathing problems
- Spine deformities
- bowed legs
- joint stiffness and arthritis
- crowding of teeth
Blood tests can be done to look for growth hormone level and other hormones affecting growth.
Treatment of Dwarfism
In some cases of metabolic and hormonal cause, the dwarfism may be reversible by supplementing for the hormone deficiency.
But there is no cure for most of the cases of dwarfism.
These people may need help with related medical conditions but these people lead normal life.
These people have special medical requirements and need regular medical consultation.
Surgery may be required for deformity correction, spine decompression, shunting the brain CSF [for hydrocephalus], tonsil removal or for weight loss.
Frequent complications that could develop and require treatment are a bowed leg, arthritis, spine deformity, neural compression, hydrocephalus, sleep apnea, and obesity.
Pregnancy in dwarfism requires cesarean for delivery as pelvis is small and vaginal delivery is not feasible.