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Trichothiodystrophy 7, nonphotosensitive(TTD7)

MedGen UID:
1684762
Concept ID:
C5231403
Disease or Syndrome
Synonyms: TRICHOTHIODYSTROPHY 7, NONPHOTOSENSITIVE; TTD7
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
141025
Concept ID:
C0441748
Intellectual Product
Sources: HPO, OMIM
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
 
Gene (location): TARS1 (5p13.3)
 
Monarch Initiative: MONDO:0032806
OMIM®: 618546

Definition

Nonphotosensitive trichothiodystrophy-7 (TTD7) is an autosomal recessive disorder characterized by cysteine- and threonine-deficient hair that displays a diagnostic alternating light and dark 'tiger-tail' banding pattern under polarization microscopy, as well as ichthyosis (Theil et al., 2019). For a discussion of genetic heterogeneity of trichothiodystrophy, see 601675. [from OMIM]

Clinical features

From HPO
Ichthyosis
MedGen UID:
7002
Concept ID:
C0020757
Disease or Syndrome
A group of inherited or acquired skin disorders characterized by a dry, thickened, and scaly skin. The skin changes range from mild to severe.
Congenital nonbullous ichthyosiform erythroderma
MedGen UID:
38180
Concept ID:
C0079154
Disease or Syndrome
Congenital ichthyosiform erythroderma (CIE) is a variant of autosomal recessive congenital ichthyosis (ARCI; see this term), a rare epidermal disease, characterized by fine, whitish scales on a background of erythematous skin over the whole body.
Brittle hair
MedGen UID:
120480
Concept ID:
C0263490
Disease or Syndrome
Fragile, easily breakable hair, i.e., with reduced tensile strength.
Follicular hyperkeratosis
MedGen UID:
83101
Concept ID:
C0334013
Disease or Syndrome
A skin condition characterized by excessive development of keratin in hair follicles, resulting in rough, cone-shaped, elevated papules resulting from closure of hair follicles with a white plug of sebum.
Cutaneous photosensitivity
MedGen UID:
87601
Concept ID:
C0349506
Pathologic Function
An increased sensitivity of the skin to light. Photosensitivity may result in a rash upon exposure to the sun (which is known as photodermatosis). Photosensitivity can be diagnosed by phototests in which light is shone on small areas of skin.
Tiger tail banding
MedGen UID:
892884
Concept ID:
C4073178
Finding
An abnormal appearance of hair under polarizing microscopy (using crossed polarizers), whereby hair shafts show striking alternating bright and dark bands, often referred to as tiger tail banding.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVTrichothiodystrophy 7, nonphotosensitive

Recent clinical studies

Diagnosis

La Serna-Infantes J, Pastor MC, Trubnykova M, Velásquez FC, Sotomayor FV, Barriga HA
Eur J Med Genet 2018 Jul;61(7):388-392. Epub 2018 Feb 5 doi: 10.1016/j.ejmg.2018.02.004. PMID: 29421601

Clinical prediction guides

Nakabayashi K, Amann D, Ren Y, Saarialho-Kere U, Avidan N, Gentles S, MacDonald JR, Puffenberger EG, Christiano AM, Martinez-Mir A, Salas-Alanis JC, Rizzo R, Vamos E, Raams A, Les C, Seboun E, Jaspers NG, Beckmann JS, Jackson CE, Scherer SW
Am J Hum Genet 2005 Mar;76(3):510-6. Epub 2005 Jan 11 doi: 10.1086/428141. PMID: 15645389Free PMC Article

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