photosensitive trichothiodystrophy 3

Photosensitive Trichothiodystrophy 3 (TTD3) Description

Photosensitive trichothiodystrophy 3, also known as TTD3, is a rare autosomal recessive disorder characterized by brittle, sulfur-deficient hair that displays a diagnostic alternating light and dark banding pattern, called 'tiger tail banding,' under polarizing microscopy [1][2]. This condition affects many parts of the body and is caused by variants in the TFB5 gene (GTF2H5) [3].

The hallmark feature of TTD3 is short, unruly, brittle hair with alternating dark and light bands under polarizing microscopy [4]. Other clinical features may include photosensitivity, ichthy

Photosensitive Trichothiodystrophy Signs and Symptoms

Trichothiodystrophy (TTD) is a rare genetic disorder that affects multiple systems in the body, including the skin. One of the clinical features of TTD is photosensitivity, which means an increased sensitivity to sunlight.

• Skin symptoms: People with TTD may experience skin symptoms such as:
  • Ichthyosis: A condition characterized by dry, scaly, and thickened skin [3][6].
  • Cutaneous photosensitivity: An increased sensitivity to sunlight, leading to skin redness, blistering, or rashes upon exposure to UV light [8].
• Other clinical features: In addition to photosensitive skin symptoms, TTD is also associated with other clinical features such as:
  • Short stature
  • Decreased fertility
  • Intellectual impairment
  • Haematological abnormalities

It's essential to note that the signs and symptoms of TTD can vary widely among individuals, even within the same family. Mild cases may involve only the hair, while more severe cases can affect multiple systems in the body.

References: [3] What is trichothiodystrophy? Trichothiodystrophy is a rare, multisystem, autosomal-recessive disorder characterised by sulphur-deficient, short, brittle hair. Other clinical features may include photosensitivity, ichthyosis, intellectual impairment, haematological abnormalities, decreased fertility, and short stature [1].. [6] The major clinical features seen in this group of conditions are brittle hair, ichthyosis, short stature, decreased fertility, intellectual impairment, ... [8] The most relevant features are hair abnormalities, physical and mental retardation, ichthyosis, signs of premature aging and cutaneous photosensitivity.

Diagnostic Tests for Photosensitive Trichothiodystrophy 3

Photosensitive trichothiodystrophy 3 (TTD3) is a rare autosomal recessive disorder characterized by brittle, sulfur-deficient hair with a distinctive 'tiger tail banding' pattern. Diagnosing TTD3 can be challenging, but several diagnostic tests are available to confirm the condition.

• Biochemical analysis of hair shafts: This test measures the low sulphur content in hair shafts, which is a hallmark of TTD3 (7). A decreased high sulphur matrix protein can also be detected through this test (13).
• Polarizing microscopy: Under polarizing microscopy, the hair shafts of individuals with TTD3 display a diagnostic alternating light and dark banding pattern, known as 'tiger tail banding' (6, 12). This is a reliable diagnostic feature of TTD3.
• Genetic testing: Genetic testing can confirm the diagnosis of TTD3 by identifying mutations in one of three genes: ERCC2, ERCC3, or GTF2H5 (4, 10). Sequence analysis of the entire coding region and next-generation sequencing technology are available for genetic testing (10).
• Clinical Molecular Genetics test: This test is specifically designed to diagnose TTD3 and involves sequence analysis of the entire coding region using next-generation sequencing technology (10).

These diagnostic tests can help confirm the diagnosis of photosensitive trichothiodystrophy 3. However, it's essential to note that genetic testing may not be available for all forms of TTD, and other conditions with similar hair shaft abnormalities may need to be ruled out through additional testing.

References: [4] [6] [7] [10] [12] [13]

Treatment Options for Photosensitive Trichothiodystrophy 3

Photosensitive trichothiodystrophy 3 is a rare and autosomal recessive disorder characterized by extreme sensitivity to light, among other symptoms. While there is no cure for this condition, various treatment options can help manage its manifestations.

• Dupilumab: A monoclonal antibody that blocks the biologic effects of interleukin (IL)-4 and IL-13 has been successfully used in treating a patient with trichothiodystrophy 3. This treatment option may be considered for patients who are extremely sensitive to light, as it can help reduce inflammation and prevent skin damage [1][2].
• Photoprotection: Adequate sun protection is essential for individuals with photosensitive trich

Differential Diagnoses for Photosensitive Trichothiodystrophy 3

Photosensitive trichothiodystrophy 3 (TTDP) is a rare autosomal recessive disorder characterized by brittle, sulfur-deficient hair and cutaneous photosensitivity. When considering differential diagnoses for TTDP, the following conditions should be taken into account:

• Cockayne Syndrome: A rare autosomal-recessive disorder of DNA repair, characterized by photosensitivity, short stature, ocular abnormalities, premature aging, and neurological dysfunction [1].
• Xeroderma Pigmentosum: A genetic disorder that affects the body's ability to repair DNA damage caused by ultraviolet (UV) light from the sun or other sources, leading to skin sensitivity and increased risk of skin cancer [not mentioned in context but relevant condition]
• Tay Syndrome: Also known as trichothiodystrophy type 1, this is a rare autosomal recessive disorder characterized by brittle hair, intellectual disability, and short stature [14].
• PIBIDS (Photosensitive Ichthyosis with Brittle Hair and Intellectual Disability Syndrome): A rare autosomal recessive disorder that presents with photosensitivity, ichthyosis, brittle hair, intellectual disability, and short stature [8].

Key Features to Consider

When differentiating TTDP from other conditions, the following features should be taken into account:

• Brittle hair: Characterized by a "tiger-tail" pattern under polarizing microscopy, which is diagnostic for trichothiodystrophy [5][7].
• Photosensitivity: A common feature in TTDP, particularly in patients with nucleotide excision repair (NER) defects [4][9].
• Ichthyosis: A skin condition characterized by dry, scaly skin that can be present in TTDP and other conditions like PIBIDS [8].

Genetic Considerations

TTDP is caused by variants in one of three genes: ERCC2, ERCC3, or GTF2H5 [4][9]. Understanding the genetic basis of TTDP can help differentiate it from other conditions.

In summary, when considering differential diagnoses for photosensitive trichothiodystrophy 3 (TTDP), it is essential to take into account the key features and genetic considerations mentioned above.