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Disease Profile

Trichothiodystrophy

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

Unknown

Age of onset

Infancy

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ICD-10

L67.8

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Categories

Congenital and Genetic Diseases; Male Reproductive Diseases; Skin Diseases

Summary

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.
orphanet

Orpha Number: 33364

Definition
Trichothiodystrophy or TTD is a heterogeneous group disorders characterized by short, brittle hair with low-sulphur content (due to an abnormal synthesis of the sulphur containing keratins).

Epidemiology
The exact prevalence of TTD is unknown, but it appears to be rather uncommon.

Clinical description
Within the spectrum of the TTD syndromes are numerous syndromes affecting mainly organs derived from the neuroectoderm. The clinical appearance is always characterized by brittle and fragile hair, often combined with growth retardation and intellectual deficit, congenital ichthyosis and nail abnormalities, among other symptoms. The abnormalities are usually obvious at birth, with variable clinical expression. The variants of TTD, depending on their different associations, are: BIDS syndrome (or TTD type D or Amish Brittle Hair syndrome), IBIDS syndrome (or Tay syndrome or TTD typeE), PIBIDS syndrome (or TTD type F), Sabinas syndrome (TTD type B), SIBIDS syndrome, ONMRS (Itin syndrome) and Pollitt syndrome (TTD type C).

Etiology
About half of the patients with TTD exhibit marked photosensitivity, due to abnormalities in excision repair of ultraviolet (UV)-damaged DNA. In most cases, the deficiency in DNA excision repair is indistinguishable from that observed in Xeroderma Pigmentosum type D. In this photosensitive group of patients, the majority of cases (95% of patients) are due to mutations within the XPD (ERCC2) gene (localized to 19q13.2-q13.3). The remaining cases are caused by mutations within the XPB gene. These genes encode the DNA-dependent ATPase/helicase subunits of TFIIH (transcription factor). So far, no gene has been isolated for the nonphotosensitive group.

Diagnostic methods
The diagnostic findings of TTD are short, unruly, brittle hair, with alternating dark and light bands under polarizing microscopy (tiger-tail pattern), trichoschisis (or trichorrhexis), and an absent or defective cuticle visualized by scanning electron microscopy.

Differential diagnosis
TTD is a differential diagnosis in congenital alopecias.

Antenatal diagnosis
Prenatal diagnosis, based on measurement of DNA repair in trophoblasts or amniotic cells, is available.

Genetic counseling
TTD is an autosomal recessive disorder.

Management and treatment
There is no specific treatment.

Visit the Orphanet disease page for more resources.

Symptoms

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
HPO ID
5%-29% of people have these symptoms
Abnormal pyramidal sign
0007256
Abnormality of prenatal development or birth
0001197
Absence of subcutaneous fat
Absent fat below the skin
Lack of fatty tissue below the skin

[ more ]

0007485
Alopecia of scalp
Pathologic hair loss from scalp
Scalp hair loss

[ more ]

0002293
Anemia
Low number of red blood cells or hemoglobin
0001903
Aplasia/Hypoplasia of the nails
Absent/small nails
Absent/underdeveloped nails

[ more ]

0008386
Astigmatism
Abnormal curving of the cornea or lens of the eye
0000483
Bilateral microphthalmos
Abnormally small eyeball on both sides
0007633
Bilateral sensorineural hearing impairment
0008619
Bird-like facies
Bird-like facial appearance
0000320
Brittle hair
0002299
Bronchospasm
0025428
Cardiomyopathy
Disease of the heart muscle
0001638
Carious teeth
Dental cavities
Tooth cavities
Tooth decay

[ more ]

0000670
Cerebral cortical atrophy
Decrease in size of the outer layer of the brain due to loss of brain cells
0002120
Cerebral dysmyelination
0007266
Clubbing
Clubbing of fingers and toes
0001217
Coarse facial features
Coarse facial appearance
0000280
Concave nail
Spoon-shaped nails
0001598
Congenital exfoliative erythroderma
0007381
Craniosynostosis
0001363
Cryptorchidism
Undescended testes
Undescended testis

[ more ]

0000028
Cutaneous photosensitivity
Photosensitive skin
Photosensitive skin rashes
Photosensitivity
Sensitivity to sunlight
Skin photosensitivity
Sun sensitivity

[ more ]

0000992
Defective DNA repair after ultraviolet radiation damage
0003079
Delayed skeletal maturation
Delayed bone maturation
Delayed skeletal development

[ more ]

0002750
Developmental cataract
Clouding of the lens of the eye at birth
0000519
Diffuse cerebellar atrophy
0100275
Dry skin
0000958
Dysarthria
Difficulty articulating speech
0001260
Dysphonia
Inability to produce voice sounds
0001618
Dystrophic fingernails
Poor fingernail formation
0008391
Ectropion
Eyelid turned out
0000656
Eczema
0000964
Epicanthus
Eye folds
Prominent eye folds

[ more ]

0000286
Esotropia
Inward turning cross eyed
0000565
Fragile nails
Brittle nails
0001808
Gait ataxia
Inability to coordinate movements when walking
0002066
Generalized hyperreflexia
0007034
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

0001290
Generalized-onset seizure
0002197
Global developmental delay
0001263
Gonadal dysgenesis
0000133
High, narrow palate
Narrow, high-arched roof of mouth
Narrow, highly arched roof of mouth

[ more ]

0002705
Hypertelorism
Wide-set eyes
Widely spaced eyes

[ more ]

0000316
Hypoplasia of dental enamel
Underdeveloped teeth enamel
0006297
Hypoplasia of mandible relative to maxilla
0410219
Hyporeflexia
Decreased reflex response
Decreased reflexes

[ more ]

0001265
Hypotelorism
Abnormally close eyes
Closely spaced eyes

[ more ]

0000601
Ichthyosis
0008064
Impaired social reciprocity
0012760
Increased bone mineral density
Increased bone density
0011001
Increased mean corpuscular hemoglobin concentration
0025548
Intention tremor
0002080
Intrauterine growth retardation
Prenatal growth deficiency
Prenatal growth retardation

[ more ]

0001511
Joint dislocation
Joint dislocations
Recurrent joint dislocations

[ more ]

0001373
Keratoconjunctivitis sicca
Dry eyes
0001097
Low-set nipples
0002562
Macular degeneration
0000608
Microcephaly
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference

[ more ]

0000252
Microcornea
Cornea of eye less than 10mm in diameter
0000482
Multiple joint

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) lists the subtypes and associated genes for Trichothiodystrophy in a table called Phenotypic Series. Each entry in OMIM includes a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.

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