THANATOPHORIC DYSPLASIA, TYPE 1
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ALTERNATE NAMES
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TD1; TDI; Dwarf, Thanatophoric; Thanatophoric Dwarfism; Thanatophoric Short Stature;
TD type 1; TD type I
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DESCRIPTION
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Thanatophoric Dysplasia, Type 1 (TD1) is a severe skeletal disorder characterized by a normal-shaped skull, curved thigh
bones and flattened bones of the spine (platyspondyly). The term thanatophoric is
Greek for “death bearing”. Infants with TD1 are usually stillborn or die shortly after
birth from respiratory failure; however, a few affected individuals have survived
into childhood with extensive medical help. This disorder is caused by mutations in
the FGFR3 gene. The gene provides instructions for making a protein that is involved
in the development and maintenance of bone and brain tissue. Mutations in this gene
cause the FGFR3 protein to be overly active, which leads to the severe disturbances
in bone growth. This condition occurs in 1 in 20,000 to 50,000 newborns.
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DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND
ICD-9-CM/ICD-10-CM
CODING
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Diagnostic testing:
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Prenatal ultrasound with findings of growth deficiency, ventriculomegaly, macrocephaly,
well-ossified skull and spine, platyspondyly of the vertebrae, micromelia, bowed femurs,
narrow chest cavity with shortened ribs and polyhydramnios; and
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Molecular genetic testing of the gene FGFR3.
Physical findings:
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Growth deficiency of limbs of less than 5%;
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Platyspondyly of the vertebrae;
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ICD-9: 756.4
ICD-10: G71.13
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PROGRESSION
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Newborns with TD1 are stillborn or die shortly after birth. Very rare reports of survival
into early childhood have been cited. Long-term survivors need neurologic, orthopedic,
and audiologic evaluations, CT to monitor for craniocervical constriction, and EEG
to monitor for seizure activity.
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TREATMENT
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Treatment measures of the few survivors may include: antiepileptic drugs to control
seizures, shunt placement for hydrocephaly, suboccipital decompression for relief
of craniocervical junction constriction, and hearing aids.
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SUGGESTED PROGRAMMATIC ASSESSMENT*
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Suggested MER for Evaluation:
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Clinical examination that describes diagnostic features of the impairment;
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Suggested Listings for Evaluation:
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DETERMINATION
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LISTING |
REMARKS
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Meets
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110.08
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Equals
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* Adjudicators may, at their discretion, use the Medical Evidence of Record or the
listings suggested to evaluate the claim. However, the decision to allow or deny the
claim rests with the adjudicator.
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