Vitamin D-Dependent Rickets, Type II

Alternative Names

  • VDDR2A
  • Vitamin D-Dependent Rickets, Type 2a, with or without Alopecia
  • Rickets, Hereditary Vitamin D-Resistant
  • HVDRR
  • Generalized Resistance to 1,25-Dihydroxyvitamin D
  • Vitamin D-Resistant Rickets with End-Organ Unresponsiveness to 1,25-Dihydroxycholecalciferol
  • Pseudovitamin D-Deficiency, Type IIA
  • PDDR IIA
  • Hypocalcemic Vitamin D-Resistant Rickets
  • HVDRR
  • Rickets-Alopecia Syndrome

Associated Genes

Vitamin D Receptor
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WHO-ICD-10 version:2010

Endocrine, nutritional and metabolic diseases

Metabolic disorders

OMIM Number

277440

Mode of Inheritance

Autosomal recessive

Gene Map Locus

12q12-q14

Description

Vitamin D-dependent rickets type II (VDDR II) is an autosomal recessive disorder resulting from the defective response of vitamin D receptors (VDR) in the target tissues to the active hormonal form of vitamin D. Vitamin D is important for enhancing the absorption of calcium from the small intestine and for normal bone development. VDDR II is characterized by the early onset of rickets, alopecia, hypocalcemia, hypophosphatemia, secondary hyperparathyroidism, and elevated 1,25-(OH)2D3 levels.

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
277440.1.1LebanonMaleYesYes Hypocalcemia ; Spasticity ; Generalize... NM_001017535.1:c.1190A>CHomozygousAutosomal, RecessiveAndary et al, 2017 Proband
277440.2.1LebanonFemaleYesYes Hypocalcemia ; Rickets ; Alopecia ; W... NM_001017535.1:c.1171C>AHomozygousAutosomal, RecessiveAndary et al, 2017 Proband
277440.3.1LebanonMaleYesYes Hypocalcemia ; Alopecia totalis ; Gene... NM_001017535.1:c.1171C>AHomozygousAutosomal, RecessiveAndary et al, 2017 Proband
277440.3.2LebanonFemaleYesYes Hypocalcemia ; Alopecia totalis ; Broa... NM_001017535.1:c.1171C>AHomozygousAutosomal, RecessiveAndary et al, 2017 Sister of 277440.3.1
277440.4.1Saudi ArabiaMaleYesYes Hypocalcemia ; Rickets ; Alopecia ; H... NM_001364085.1:c.137G>THomozygousAutosomal, RecessiveLin et al. 1996 Proband
277440.5.1United Arab EmiratesMaleYesYes Hypocalcemia ; Broad carpal bones ; Ra... NM_001364085.1:c.821G>AHomozygousAutosomal, RecessiveAljubeh et al. 2011 Proband
277440.6.1United Arab EmiratesFemaleNoNo Hypocalcemia ; Rickets ; Broad carpal ... NM_001364085.1:c.821G>AHomozygousAutosomal, RecessiveAljubeh et al. 2011

Other Reports

Bahrain

Khan et al, 1996 were the first to report vitamin D-dependent rickets type II (VDDR II) in a consanguineous Bahraini family. 

[Khan IM, Al-Hermi B, Al-Abbasi AJ, Al-Rufai M, Al-Arrayed S. Hereditary 1,25-dihydroxyvitamin D-resistant rickets: a report of several cases in a kindred. Bahrain Med Bull. 1996; 18(1):28-30.]

Kuwait

Al Anzy et al, 1998 described the clinical features of three siblings with clinically different severity of vitamin D dependent rikets type II with alopecia. 

[Al-Anzy HM, Alsaleh QA, Salem MT, Nadi H, Sameer E. A new variant of 1,25-dihydroxyvitamin D-receptor-defect rickets and alopecia associated with mental retardation and hearing loss. Gulf J Dermatol. 1998; 5(1):30-1.]

Oman

Paul and Al-Khusaiby, 1987 reported vitamin D dependent rickets with alopecia in an 18-month-old Omani male born to non-consanguineous parents.

[Paul G, Al-Khusaiby SBM. Vitamin D dependent rickets type II with alopecia. Medical Newsletter. 1987; 3(3):2-6.] 

Saudi Arabia

Al-Khenaizan and Vitale, 2003 report two Saudi brothers with vitamin D-dependent rickets type II disease associated with alopecia of the scalp or the body.

United Arab Emirates

Jabur, 2009 described the clinical features of two sisters with osteomalacia.

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