Download Hereditary Vitamin D-Resistant Rickets, (HVDRR)

SKELETALDISORDERS
HereditaryVitaminD-ResistantRickets,
(HVDRR)
Inbrief
Hereditary vitamin D-resistant rickets (HVDRR) is characterised by
defectsinthevitaminDreceptorsoftheend-organs.Bonemineralization
is inhibited in HVDRR causing softening and bending of the bones and
skeletal malformations. The clinical signs of HVDRR include limb
deformitiesandjointpain.ThecausativemutationforHVDRRhasbeen
identified in Pomeranians. The condition is inherited as an autosomal
recessivetrait.
Clinicaloverview
The underlying cause for hereditary vitamin D-resistant rickets is a
defectinthevitaminDreceptorthatpreventsvitaminDfromreachingits
target tissues. HVDRR is characterised by low calcium levels leading to
secondaryhyperparathyroidism.VitaminDenhancesbonemineralization
andcalciumisessentialforhardnessandstrengthofthebones.Vitamin
D-resistance causes dysfunctional bone mineralization leading to the
softeningofbonesandskeletaldeformities.TheclinicalsignsofHVDRR
includejointpain,lameness,limbdeformities,spontaneousfractures,jaw
deformities, and neurological signs. HVDRR can also cause alopecia
(hairlessness). Affected dogs can be treated by oral administration of
active vitamin D and calcium supplements. The bone deformities are,
however,irreversible.
References
Onlinedatabase
OnlineMendelianInheritanceinAnimals,OMIA
(http://omia.angis.org.au/).FacultyofVeterinaryScience,Universityof
Sydney.
Scientificarticles
LeVineDN,ZhouY,GhiloniRJ,FieldsEL,BirkenheuerAJ,GookinJL,
RoberstonID,MalloyPJ,FeldmanD.Hereditary1,25-dihydroxyvitaminDresistantricketsinaPomeraniandogcausedbyanovelmutationinthe
vitaminDreceptorgene.JVetInternMed23:1278-83,2009.
Diseaseseverity
Severe
Clinicalsigns
Hypocalcemia
Secondary
hyperparathyroidism
Hypomineralisationofbones
Bonemalformations
Rickets
Jointpain
Lameness
Limbdeformities
Spontaneousfractures
Alopecia
ModeofInheritance
AutosomalRecessive
Resultsofthegenetic
testarereportedas
follows:
Clear
Carrier
Atrisk
Mutation(s)foundin:
Pomeranian