Is dermatophytosis inherited?

Is Dermatophytosis Inherited?

While dermatophytosis itself is not directly inherited, there is evidence of a genetic basis for susceptibility to certain forms of dermatophytosis, particularly onychomycosis, which follows an autosomal dominant pattern of inheritance in some families. 1

Genetic Factors in Dermatophytosis

• Recent studies suggest a genetic basis for susceptibility to onychomycosis, with familial patterns of distal lateral onychomycosis caused by T. rubrum infection that appeared unrelated to interfamilial transmission 1
• Several studies have reported an autosomal dominant pattern of inheritance associated with T. rubrum infection, highlighting the increased risk of developing onychomycosis in subjects where at least one parent had onychomycosis 1
• Genome-wide association studies have identified specific genetic markers associated with dermatophytosis susceptibility, including a significant association with the Tubulointerstitial Nephritis Antigen (TINAG) gene, where carrying two minor G alleles at SNP rs16885197 raised dermatophytosis odds ratio by a factor of 14 2

Specific Genetic Associations

• Genetic analyses have revealed several proven genetic relationships in dermatophytosis susceptibility, including:
  • CARD9 deficiency 2
  • HLA-DR4 and HLA-DR8 types 2
  • Genes encoding interleukin-22 and β-defensin 2 and 4 2
  • Genetic defects in dectin-1 2

Non-Genetic Risk Factors for Dermatophytosis

• While genetic factors play a role in susceptibility, dermatophytosis is primarily an infectious disease caused by dermatophytes, which are keratinophilic fungi that invade keratinized tissue (skin, hair, nails) 3
• Important non-genetic risk factors include:
  • Increasing age (20% prevalence in those over 60 years, up to 50% in those over 70) 1, 4
  • Male gender 1, 4
  • Reduced peripheral circulation 1
  • Immunosuppression (HIV infection, transplant recipients) 1, 4
  • Diabetes mellitus 1
  • Previous nail trauma 1
  • Hyperhidrosis 1

Clinical Implications of Genetic Susceptibility

• Understanding genetic predisposition to dermatophytosis has important implications for:
  • Identifying high-risk individuals who may benefit from prophylactic measures 2
  • Educating family members about increased susceptibility 2
  • Developing targeted therapeutic approaches for those with genetic predisposition 2
• In immunocompromised patients with genetic susceptibilities, dermatophytosis can present as severe forms including extensive and/or invasive dermatophytosis 5

Transmission and Infection

• Despite genetic predisposition, dermatophytosis remains a communicable disease that requires exposure to the causative fungi 3
• Transmission occurs through:
  • Contact with infected individuals 1
  • Contact with infected animals (zoonotic transmission) 3
  • Exposure to contaminated fomites or environments 3
• Arthroconidia (fungal spores) are the primary infectious particles involved in the spread of dermatophyte infections 1

In summary, while dermatophytosis is an infectious disease requiring exposure to dermatophytes, genetic factors significantly influence individual susceptibility, particularly for onychomycosis, which shows clear patterns of familial inheritance following an autosomal dominant pattern in some cases.