Benign Hereditary Chorea/Brain-Thyroid-Lung Syndrome
Choreoathetosis, Congenital Hypothyroidism and Neonatal Respiratory Distress
Gene: NKX2-1
Protein: homeobox protein Nkx-2.1
Clinical Characteristics
Benign Hereditary Chorea
- Childhood onset chorea, usually before age 5 years
- Delayed motor development
- Dysarthria and gait abnormalities may occur
- No dementia (in contrast to Huntington’s disease)
- Little or no progression beyond second decade of life
Choreoathetosis, Congenital Hypothyroidism and Neonatal Respiratory Distress
- Also known as brain-lung-thyroid syndrome
- Onset at birth
- Involuntary movements
- Neonatal respiratory distress and risk for recurrent respiratory infections
- Congenital hypothyroidism
- Global developmental delay
- Hypotonia, ataxia and dysarthria may occur
Both show variable expressivity between, and within, families.
Inheritance pattern: Autosomal dominant
What Can Be Learned From This Test
Testing is performed by sequencing the entire coding region of NKX2-1. This will detect point mutations, small deletions and small insertions. Copy number analysis will be performed to detect a whole or partial gene deletion, since deletions of the entire NKX2-1 gene have been reported in affected individuals.
NKX2-1 is the only gene known to be associated with these specific disorders. However, a negative test result does not rule out a genetic cause of early onset chorea or congenital hypothyroidism. There are other genes associated with other types of movement disorders, as well as other hypothyroid disorders.
Sample Requirements
Draw 2ml–4ml of blood in EDTA/purple-top tube (minimum of 1ml–2ml for infants).
Turnaround time: 10-14 business days
CPT Codes and Cost
Full Gene Sequencing & Deletion Testing
Code: 81479
Cost: $600
Known Variant Testing
Code: 81479
Cost: $225