Trichothiodystrophy (TTD) is an autosomal recessive inherited disorder characterised by brittle hair and intellectual impairment. The word breaks down into tricho – "hair", thio – "sulphur", and dystrophy – "wasting away" or literally "bad nourishment". TTD is associated with a range of symptoms connected with organs of the ectoderm and neuroectoderm. TTD may be subclassified into four syndromes: Approximately half of all patients with trichothiodystrophy have photosensitivity, which divides the classification into syndromes with or without photosensitivity; BIDS and PBIDS, and IBIDS and PIBIDS. Modern covering usage is TTD-P (photosensitive), and TTD.[1]


BIDS syndrome
Classification and external resources
OMIM 234050
DiseasesDB 32649

Features of TTD can include photosensitivity, icthyosis, brittle hair and nails, intellectual impairment, decreased fertility and short stature. The acronyms PIBIDS, IBIDS, BIDS and PBIDS give the initials of the words involved. BIDS syndrome, also called Amish brittle hair brain syndrome and hair-brain syndrome,[2] is an autosomal recessive[3] inherited disease. It is nonphotosensitive. BIDS is characterized by brittle hair, intellectual impairment, decreased fertility, and short stature.[4]:501 There is a photosensitive syndrome, PBIDS.[5]

BIDS is associated with the gene MPLKIP (TTDN1).[6]

Classification and external resources
OMIM [7] 601675[7]

IBIDS syndrome, following the acronym from ichthyosis, brittle hair and nails, intellectual impairment and short stature, is the Tay syndrome or sulfur-deficient brittle hair syndrome, first described by Tay in 1971.[8] (Chong Hai Tay was the Singaporean doctor who was the first doctor in South East Asia to have a disease named after him). Tay syndrome should not be confused with the Tay-Sachs disease.[4]:485[9][10][11] It is an autosomal recessive[12] congenital disease.[4]:501[13] In some cases, it can be diagnosed prenatally.[14] IBIDS syndrome is nonphotosensitive.

The photosensitive form is referred to as PIBIDS, and is associated with ERCC2[9] and ERCC3.[7]

Photosensitive forms

All photosensitive TTD syndromes have defects in the nucleotide excision repair (NER) pathway, which is a vital DNA repair system that removes many kinds of DNA lesions. This defect is not present in the nonphotosensitive TTD's.[15] These type of defects can result in other rare autosomal recessive diseases like xeroderma pigmentosum and Cockayne syndrome.[16]

See also


  1. Lambert WC, Gagna CE and Lambert MW. Trichothiodystrophy: Photosensitive, TTD-P, TTD, Tay Syndrome.PMID 20687499
  2. Online Mendelian Inheritance in Man (OMIM) 234050
  3. Baden, H. P.; Jackson, C. E.; Weiss, L.; Jimbow, K.; Lee, L.; Kubilus, J.; Gold, R. J. (Sep 1976). "The physicochemical properties of hair in the BIDS syndrome". American Journal of Human Genetics. 28 (5): 514521. PMC 1685097Freely accessible. PMID 984047.
  4. 1 2 3 Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.
  5. Hashimo S, and Egly JM. Trichothiodystrophy view from the molecular basis of DNA repair transcription factor
  6. Nakabayashi K, Amann D, Ren Y, et al. (March 2005). "Identification of C7orf11 (TTDN1) gene mutations and genetic heterogeneity in nonphotosensitive trichothiodystrophy". Am. J. Hum. Genet. 76 (3): 510–6. doi:10.1086/428141. PMC 1196401Freely accessible. PMID 15645389.
  7. 1 2 3 Online Mendelian Inheritance in Man (OMIM) 616390
  8. Tay CH (1971). "Ichthyosiform erythroderma, hair shaft abnormalities, and mental and growth retardation. A new recessive disorder". Arch Dermatol. 104 (1): 4–13. doi:10.1001/archderm.104.1.4. PMID 5120162.
  9. 1 2 Online Mendelian Inheritance in Man (OMIM) 601675
  10. Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN 1-4160-2999-0.
  11. Hashimoto S, and Egly JM,
  12. Stefanini M, B. E.; Botta, E.; Lanzafame, M.; Orioli, D. (January 2010). "Trichothiodystrophy: from basic mechanisms to clinical implications". DNA Repair. 9 (1): 210. doi:10.1016/j.dnarep.2009.10.005. PMID 19931493.
  13. James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology (10th ed.). Saunders. p. 575. ISBN 0-7216-2921-0.
  14. Kleijer WJ, van der Sterre ML, Garritsen VH, Raams A, Jaspers NG (Dec 2007). "Prenatal diagnosis of xeroderma pigmentosum and trichothiodystrophy in 76 pregnancies at risk". Prenat. Diagn. 27 (12): 1133–1137. doi:10.1002/pd.1849. PMID 17880036.
  15. Hashimoto S, and Egly JM
  16. Peserico, A.; Battistella, P. A.; Bertoli, P. (1 January 1992). "MRI of a very rare hereditary ectodermal dysplasia: PIBI(D)S". Neuroradiology. 34 (4): 316–317. doi:10.1007/BF00588190.
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