nonphotosensitive trichothiodystrophy 5

Nonphotosensitive Trichothiodystrophy (TTD7) Description

Nonphotosensitive trichothiodystrophy, also known as TTD7, is a rare autosomal recessive disorder characterized by specific features in the hair. The hallmark of this condition is the presence of brittle and sulfur-deficient hair that displays a distinctive "tiger-tail" banding pattern [5]. This unique characteristic is a diagnostic feature of nonphotosensitive trichothiodystrophy, making it an important tool for diagnosis.

In individuals with TTD7, the hair is often described as being short and brittle, with a tendency to break easily. The sulfur deficiency in the hair is a key feature of this condition, which distinguishes it from other forms of trichothiodystrophy [5].

Overall, nonphotosensitive trichothiodystrophy (TTD7) is a rare genetic disorder that affects the hair and is characterized by its distinctive features.

References:

• [5] Description. Trichothiodystrophy is a rare autosomal recessive disorder in which patients have brittle, sulfur-deficient hair that displays a diagnostic "tiger-tail" banding pattern.
• [8] Nonphotosensitive trichothiodystrophy-7 (TTD7) is an autosomal recessive disorder characterized by cysteine- and threonine-deficient hair with a 'tiger-tail' banding ...

Diagnostic Tests for Nonphotosensitive Trichothiodystrophy 5

Nonphotosensitive trichothiodystrophy 5 is a rare inherited condition that affects many parts of the body. The diagnostic tests for this condition are crucial in confirming the diagnosis.

• Genetic Testing: Genetic testing is often necessary to confirm the diagnosis of nonphotosensitive trichothiodystrophy 5. This involves analyzing the genes responsible for the condition, which can help identify mutations or abnormalities that contribute to the development of the disease [1].
• Biochemical Analysis: Biochemical analysis of hair shafts can also be used to diagnose nonphotosensitive trichothiodystrophy 5. This test measures the sulfur content in the hair, which is typically low in individuals with this condition [6][7].
• Exome-Based NextGen Sequencing: Exome-based next-generation sequencing (NGS) with CNV analysis is a favored testing approach for nonphotosensitive trichothiodystrophy 5. This test allows for cost-effective reflexing to PGxome or other exome-based tests [8].

It's essential to note that the diagnosis of nonphotosensitive trichothiodystrophy 5 may involve a combination of these tests, and the specific diagnostic approach may vary depending on individual circumstances.

References: [1] - Context result 4 [6] - Context result 6 [7] - Context result 7 [8] - Context result 8

Differential Diagnosis of Nonphotosensitive Trichothiodystrophy

Nonphotosensitive trichothiodystrophy (TTD) is a rare autosomal recessive disorder characterized by short, brittle hair and multisystem abnormalities. The differential diagnosis for nonphotosensitive TTD includes:

• Cockayne syndrome: A rare autosomal–recessive disorder of DNA repair that presents with photosensitivity, distinctive facial appearance, short stature, ocular abnormalities, premature aging, and neurological dysfunction.
• Other congenital alopecias: Nonphotosensitive TTD can be a differential diagnosis in cases of congenital alopecia, where the hair is short, dry, brittle, and sulfur-deficient.

Key Features

The main diagnostic criteria for nonphotosensitive TTD include:

• Brittle hair with low sulfur content
• Mental and growth retardation
• Typical facies (facial appearance)
• Ichthyosis (dry, scaly skin)

Genetic Basis

Variants in at least seven genes have been reported to cause non-photosensitive forms of trichothiodystrophy. The most commonly affected gene is the MPLKIP gene.

References

• [6] Trichothiodystrophy (TTD) is a rare, autosomal recessive disease, characterized by brittle, sulfur deficient hair and multisystem abnormalities.
• [7] The main diagnostic criteria of TTD are brittle hair, mental and growth retardation, typical facies, and ichthyosis. The hair abnormalities are considered the hallmark feature of nonphotosensitive TTD.
• [9] Variants in at least seven genes have been reported to cause non-photosensitive forms of trichothiodystrophy.
• [12] Establishing a differential diagnosis in patients with a suspected LD or gLE will begin by identifying these clinical features, assessing neurologic and systemic symptoms, and then performing appropriate diagnostic investigations (i.e. genetic testing).