Primordial Dwarfism

Group of bone growth disorders

World's Shortest Man Visits Sydney. Credit: Newspix / Contributor / Getty Images

Primordial dwarfism is a group of disorders in which growth is proportional but severely delayed, beginning in the womb. This type of dwarfism is responsible for some of the smallest people in the world. There are over 200 different types of dwarfism, all of which involve bone growth disorders (osteodysplasia) that result in short stature (adult height less than 4-feet-10-inches tall). 

Some people prefer the term "short stature" rather than "dwarf" or "dwarfism." So it's important to be sensitive to the preference of someone who has this disorder.

Short stature disorders do not include familial short stature — short height that's considered a normal variation with normal bone development.

Primordial dwarfism disorders include:

Since these conditions are rare, it is difficult to know how often they occur. It is estimated that about 100 individuals worldwide have been identified as having MOPD Type II. Both males and females of all ethnic backgrounds are affected. Some families have more than one child with MOPD Type II, which suggests that the disorder is inherited in an autosomal recessive pattern.

Symptoms of Primordial Dwarfism

The first symptom of primordial dwarfism is the failure of the fetus to grow normally in the womb, a condition called intrauterine growth retardation (IUGR). At birth, the infant with primordial dwarfism is very small, usually weighing less than 3 pounds (1.4 kg) and is less than 16 inches in length.

Often, the infant is born prematurely at about 35 weeks' gestation. He is fully formed and proportional, but very tiny.

After birth, the child grows extremely slowly, and remains far behind his peers in weight and height. The child develops:

  • Change in body proportions -- the head grows more slowly than the rest of the body (microcephaly) and bones of the arms and legs shorten
  • Loose joints with occasional dislocation or subluxation of the knees, elbows or hips
  • Characteristic facial features associated with the particular syndrome; in MOPD II, prominent nose and eyes, abnormally small or missing teeth, and a high squeaky voice
  • Spine problems such as curvature (scoliosis)

Diagnosing Primordial Dwarfism

Since primordial dwarfism disorders are extremely rare, misdiagnosis is common. Because children with primordial dwarfism do not grow like other children, poor nutrition, a metabolic disorder, or a digestive disorder may be diagnosed initially. The correct diagnosis may not be made until time has passed and it becomes apparent that the child has severe dwarfism, and other causes of the child's small stature have been excluded. Bone x-rays will show changes characteristic of primordial dwarfism, such as thinning of bones and widening of the ends of the long bones.

Treating Primordial Dwarfism

What causes primordial dwarfism is not yet known, and there are as yet no effective treatments for increasing the rate of growth in an affected child. The lack of normal growth in the disorder is not due to a deficiency of growth hormone, as in hypopituitary dwarfism. Giving growth hormones, therefore, has little or no effect on the growth of the individual with PD.

Medical care focuses on treating problems that may develop, such as feeding difficulty in infancy, vision problems, scoliosis, and joint dislocations.


Hall, J.G., Flora, C., Scott, C. Jr., Pauli, R., & Tanaka, K. "Majewski osteodysplastic primordial dwarfism type II (MOPD II): Natural history and clinical findings." American Journal of Medical Genetics 130(2004): 55-72. Print.

Mayo Clinic. Dwarfism.

"Medical Information." 14 Jul 2009.

"Primordial Dwarfism." Skeletal Dysplasia & Disorders. 8 Apr 2009. The Nemours Foundation. 14 Jul 2009.

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