What are the physical characteristics of Primordial Dwarfism?

Below are 3 photographs of patients with MOPD II. Probably the most consistent physical characteristic in these children is severe intrauterine growth retardation (IUGR). Recognition of the deficiency can occur as early as 13 weeks gestation and it becomes progressively more severe over the length of the pregnancy. At term infants typically weigh less than 3 lbs and are less than 16 inches in length. Most children however are born slightly premature at 35 weeks with an average birth weight of 2 lbs 3 oz. This is about the average size of a 28 week premature neonate. Adult heights are typically less than 33" and the voice is high pitched.

Face and Skull:

• Microcephaly. Head size is proportionate to body size at birth. However, as children grow and develop, the head grows slower than the body and becomes disproportionately small.
• Premature closure of the soft spots (fontanelles) and craniosynostosis
• Prominent nose and eyes. The conspicuous nose may be obvious at birth or it may develop over the first year.
• Small teeth with deficient enamel and increased spaces between them. Small roots in the secondary teeth. Secondary teeth can be missing or lost prematurely.

Trunk, Chest and Spine:

• Proportionately small trunk, chest, and spine.
• Scoliosis and thoracic kyphosis in later childhood

Arms and legs:

• Disproportionately short forearm in childhood, causing mesomelia.
• Dislocated radial head with decreased range of motion at the elbows.
• Dislocated hips and coxa vara at birth.
• Lumbar lordosis, as a consequence of coxa vara.
• Ligamentous laxity develops with age

Other characteristics:

• Fine and relatively sparse hair.
• Pigmentary dysplasia of the skin.

What are the x-ray characteristics?

In the newborn, the x-rays typically do not demonstrate major structural abnormalities, although the pelvis is narrow with small iliac wings and flattened acetabular angles. The long bones may be overtubulated. Eleven rib pairs are sometimes seen, rather than twelve. As the children age, the bones appear thin and delicate with progressive metaphyseal widening at the ends of the long bones.

Bone age studies usually show decreased bone age; that is, the skeletal maturation process is slowed in these children and can be delayed 2 - 5 years behind the actual age.

• What are the physical characteristics of Primordial Dwarfism?
• How is the diagnosis made?
• What are the associated medical problems?
• What are things to watch out for?
• References