Trichothiodystropy (TTD) Flashcards
What is TTD?
It stands for Trichothiodystrophy, a rare inherited disorder affecting neuro-development as well as the hair and skin.
Which medical specialties are involved in TTD management?
Dermatology,
Neonatology,
Paediatrics,
Ophthalmology,
Neurology,
Dentistry,
Infectious disease,
Genetics,
Haematology,
Immunology.
Name 3 characteristics features of TTD.
Photosensitivity
Brittle hair
Intellectual impairment
What are the common acronyms to describe TTD features?
PIBIDS
•photosensitivity
•Ichthyosis
•Brittle hair
•Intellectual impairment
•Decreased fertility
•short Stature
IBIDS
•Ichthyosis
•Brittle hair
•Intellectual impairment
•Decreased fertility
•Short stature
BIDS
•Brittle hair
•Intellectual impairment
•Decreased fertility
•Short stature
What are the common infections in TTD patients?
Respiratory
Gastrointestinal
Urinary
Ear
What is a common skin issue with TTD patients?
Ichthyosis
How is TTD diagnosed?
Low sulphur content on hair, Trichoschisis (tiger-tail banding)
Absent/damaged hair cuticle
What differentiates TTD from Xeroderma pigmentosum (XP) and Cockayne syndrome (CS)?
TTD patients are not at increased risk of developing skin cancer and do not develop pigment art abnormalities.
What is the primary treatment for Ichthyosis in TTD?
Frequent application of moisturisers and exfoliation.
How should TTD patients manage their hair?
Conservative hairdressing,
Avoiding high heat tools,
Routine use of conditioner.
What is the main cause of TTD?
Mutations or variants in specific genes
How many genes have been identified as causal factors in TTD?
A minimum of 10 different genes.
Which genes are primarily associated with the photosensitive form of TTD?
ERCC2
ERCC3
GTF2H5
What is the TFIH complex?
Also known as Transcription Factor IIH
It is a multi sub-unit protein complex, involved in important cellular processes such as DNA repair and gene transcription.
It plays a dual role in facilitating DNA damage repair, especially from UV radiation and initiating gene transcription.
Mutations in components of this complex are often implicated in the photosensitive form of TTD
What is the role of the TFIH complex?
Involved in DNA repair and gene transcription.
What type of DNA repair does the TFIH complex primarily deal with?
Damage incurred by IV radiation.
What phase of protein synthesis is the TFIH complex crucial for?
The initial phase known as gene transcription.
What deficiency is commonly observed in TTD patients?
Deficiency in proteins rich in sulphur
What are the sulphur rich proteins typically responsible for?
Conferring strength to hair strands
What unique pattern is observed in the cross section of hair from individuals with TTD?
Alternating dark and light bands, often likened to a tiger tail.
What spectrum do the manifestations of TTD span?
From mild impact on hair quality to severe developmental delays and susceptibility to recurrent conditions.
What pregnancy complications May mothers of children with TTD face?
Pregnancy-induced hypertension (preeclampsia) and HELLP syndrome (a severe form of preeclampsia, HELLP stands for:
Hemolysis (the process of the breakdown or destruction of red blood cells)
Elevated liver enzymes
Low platelet count
What characteristics are common among children affected by TTD?
Premature delivery
Low birth weight
Stunted growth
What common neurological symptom is found in TTD?
Reduced myelin formation, known as dysmyelination.
How does TTD impact cognitive abilities?
Cognitive impairments and developmental lags are prevalent.
What are common infection related concerns in TTD?
Frequent respiratory infections that can be life threatening
What blood cell abnormalities are found in TTD?
Abnormal red blood cells and elevated levels of haemoglobin subtype A2
What skin symptoms are common in TTD?
Ichthyosis
Nail deformities
Congenital cataracts
What are characteristic hair abnormalities in TTD?
Brittle, sparse hair prone to breakage, especially during febrile illnesses
What do lab tests reveal about the hair in TTD patients?
Diminished sulphur content and aberrant levels of the amino acid cystine.
What are common symptoms related to nail in TTD?
Onychodystrophy; nails may be short, wide, ridged or thick and brittle.
How does TTD affect eyebrows and eyelashes?
Eyebrows are frequently sparse and fragile, while eyelashes may appear nearly normal.
What conditions closely resemble TTD in terms of DNA excision repair defects?
Xeroderma pigmentosum (XP)
Cockayne syndrome (CS)
What diagnostic tests are key in differentiating TTD from XP and CS?
DNA repair assays and gene sequencing
What unique skin feature sets TTD apart from XP?
TTD does not have an elevated risk of skin cancer or pigment art abnormalities
What unique facial characteristics are seen in CS?
Deep set eyes
Prominent ears
What is one diagnostic tool to do efferent iate between TTD, XP and CS regarding hearing?
Audiometric tests
What are the primary symptoms of Menkes disease (MD)?
Abnormal hair structure
Neuro-degeneration
Issues with connective tissue
What is trichorrexis invaginata?
A unique hair shaft defect known as bamboo hair, commonly seen in Netherton syndrome (another DD of TTD)
What are the symptoms of acrodermatitis eneropathica?
Dermatitis
Diarrhoea
Alopecia
(All correctable with zinc supplementation)
What nutritional conditions can mimic TTD symptoms?
Malnutrition
Acrodermatitis enteropathica
What metabolic disorders can present symptoms similar to TTD?
Argininosuccinate lyase deficiency
Ornithine carboxylase deficiency
What test can rule out metabolic disorders that mimic TTD?
Urinary amino acid analysis
