THG1L-related disorder is associated with a spectrum of features:
• Developmental delays
• Small or underdeveloped cerebellum (cerebellar hypoplasia)
• Impaired coordination (ataxia)
• Abnormal involuntary eye movements (nystagmus)
• Slow or slurred speech due to weakness of the muscles used for speech (dysarthria)
• Low muscle tone (hypotonia)
• Smaller than expected head circumference (microcephaly)
• Seizures
• Softening and floppiness of the tissues of the voice box (laryngomalacia)
• Heart abnormalities*
• Abnormalities of the blood*
• Inguinal hernia*
• Slow growth in the womb (intrauterine growth restriction)
*Symptom only reported in one individual
Individuals with two copies of the specific variant p.(Val55Ala) variant have been reported with mild and slowly progress or non-progressive features. These features include mild motor developmental delays, ataxia, cerebellar vermis hypoplasia, and near normal/ normal intelligence.
Individuals with one copy of the p.(Val55Ala) variant and one copy of another variant, have been reported to have more severe symptoms.
THG1L