TABLE 1.

Summary of the alopecia scalp and hair follicle microbiota.

STUDY	TYPE OF ALOPECIA	MICROBIOME SAMPLING TECHNIQUE	SEQUENCING METHOD	FINDINGS
Juhasz et al, 202018	AA	Swab sample	16S rRNA and ITS 16S rRNA sequencing	Decreased Clostridia and Malasseziomycetes in AA scalp relative to control.
Pinto et al, 202016	AA	Swab and biopsy samples	16S rRNA sequencing	Swab results: Increased Propionibacterium acnes and decreased Staphylococcus epidermidis in AA relative to control. Biopsy results: Decreased Acinetobacter genus, Candidatus Aquiluna rubra, Staphylococcus epidermidis, and 2 genera of Microthrixacea and ACK-M1 families in AA dermis. Increased Anaerococcus and Neisseria, decreased Staphylococcus, and absent SMB53 in AA epidermis relative to control.
Filaire et al, 202012	AGA	Swab sample	16S rRNA sequencing and amplification of ITS1 regions	Decreased Malassezia genus and increased Wallemia and Eurotium genera in AGA relative to healthy subjects. Significantly decreased M. restricta and M.globosa in AGA relative to healthy subjects
Pinto et al, 201915	AA	Swab and biopsy samples	16S rRNA sequencing	Swab results: Increased Cutibacterium acnes and decreased Staphylococcus epidermidis in AA relative to control. Increased ratio of C. acnes/S.epidermidis and increased ratio of C.acnes/S.aureus in AA. Biopsy results: Increased Proteobacteria, Bacteroidetes, and Firmicutes in AA relative to control. Prevotella copri and Akkermansia muciniphila were found in the AA subepidermal compartments.
Ho et al, 201934	AA	Biopsy sample	16S rRNA sequencing	Increased microbial variation in AGA vs control in lower portion of the hair follicle relative to middle. Increased C. acnes and decreased Brevibacterium in lower portion of AGA occipital follicle vs control. Association between microbial changes in AGA and hair follicle miniaturization. Increased C. acnes and decreased Burkholderia spp. in middle portion of miniaturized follicles from vertex vs non-miniaturized in AGA. Decreased M. komagatae, Sphingomonadaceae, and Brevibacterium in lower portion of miniaturized follicles from vertex vs non-miniaturized in AGA.
Huang et al, 201940	AGA	Hair root sample	High Throughput- Sequencing	Increased positivity rate for Malassezia in AGA specimen than control. Increased Malassezia abundance in the calvaria area in AGA relative to control. Increased Malassezia on scalp relative to occipital region in AGA. Increased M. globosa and M. restricta in the calvaria area and occipital area in AGA relative to control.