1. Confirm the diagnosis by radiographic studies
(the diagnosis of approximately 20% of patients with achondroplasia
has been missed in the past, because it was not suspected on physical
examination in the newborn period and consequently no radiographs
2. Document measurements, including arm span, occipital
frontal circumference (OFC), body length, and upper to lower body
segment ratio. Review the phenotype with the parents and discuss
the specific findings with both parents whenever possible.
3. The OFC should be measured monthly during the
first year. Ultrasound studies of the brain to determine ventricular
size should be considered if the fontanelle size is unusually large,
OFC increases disproportionately, or symptoms of hydrocephalus develop.
1. Discuss the specific findings of achondroplasia with the parents,
-- Autosomal dominant
inheritance. About 75% of cases are new mutations. Germline mosaicism
(in which some germ cells are derived from a normal cell line and
some are from a cell line with a mutation) has been reported, but
clearly the risk of recurrence in sporadic cases is far below 1%.
-- Most individuals with
achondroplasia have normal intelligence and normal life expectancy.
-- Growth hormone and
other drug therapies are not effective in increasing stature. Experimental
work is being done on leg-lengthening procedures at an older age
-- Special achondroplasia
growth curves and infant development charts have been developed,
and the final expected adult height for persons with achondroplasia
is in the range of about 4 ft .
2. Discuss the following
possible severe medical complications:
-- Unexpected infant
death in less than 3% of those affected, usually only in the most
severe cases . Severe upper airway obstruction in less than
5% of those affected, but consider sleep studies if there appears
to be a problem with breathing at rest or during sleep, especially
if developmental landmarks lag .
-- Restrictive pulmonary
disease with or without reactive airway disease occurs in less than
5% of children with achondroplasia who are younger than 3 years
; consider pulse oximetry or evaluation for cor pulmonale if
there are signs of breathing problems.
-- Development of thoracolumbar
kyphosis is associated with unsupported sitting before there is
adequate trunk muscle strength .
-- All infants with achondroplasia
have a relatively small foramen magnum, but few become symptomatic
from cord compression at the cervicomedullary junction . This
complication may be manifested by signs and symptoms of a high cervical
myelopathy, central apnea, or both . Rarely, formamen magnum
decompression may be recommended.
-- Hydrocephalus may
develop during the first 2 years , so OFC size should be monitored
carefully during this time. If a problem is suspected, refer the
infant to a pediatric neurologist or pediatric neurosurgeon.
-- The common complication
of spinal stenosis rarely occurs in childhood but manifests in older
individuals with numbness, weakness, and altered deep tendon reflexes
. Children with severe thoracolumbar kyphosis are at greater
risk for this problem. It is for this reason that unsupported sitting
before there is adequate trunk muscle strength is discouraged.
3. Discuss the psychosocial
issues related to disproportionate short stature. Refer the affected
individual, or the parent of an affected individual, to a support
group such as Little People of America or Human Growth Foundation
(see ÒResources for New ParentsÓ). If parents do not
wish to join a group, they may want to meet with or talk to other
affected individuals or parents. Remind parents that most individuals
with achondroplasia lead productive, independent lives.
4. Discuss with the parents
how to tell their family and friends about their childÕs
5. Supply the parents
with educational books and pamphlets (see ÒResources for
6. Discuss the realistic
functional problems for affected individuals.
7. Discuss individual
resources for support, such as family, clergy, social workers, and
8. Review the prenatal
diagnosis and recurrence risks for subsequent pregnancies.