Calcitriol-resistant rickets with alopecia.

Area of Science:

• Endocrinology
• Genetics
• Dermatology

Background:

• Vitamin D is crucial for bone health and calcium homeostasis.
• Defects in vitamin D metabolism or receptor function can lead to rickets.
• Alopecia, or hair loss, can have various underlying causes.

Observation:

• Four children from two families presented with severe rickets resistant to standard treatment.
• These children also exhibited alopecia (hair loss).
• Scalp biopsies showed normal hair and follicle morphology.

Findings:

• The rickets and alopecia were attributed to defective cytoplasmic and nuclear receptors for calcitriol (1,25-dihydroxyvitamin D3).
• This indicates a genetic basis for calcitriol resistance.
• The hair loss was not due to apparent abnormalities in the hair follicles themselves.

Implications:

• Calcitriol-resistant rickets should be recognized as an inherited disorder affecting hair growth.
• The co-occurrence of rickets and alopecia warrants consideration in the differential diagnosis of hair loss.
• This highlights the systemic effects of vitamin D receptor defects beyond bone metabolism.