Johns Hopkins, gene NKX2-1, Benign Hereditary Chorea

Message

Collect at NMCP only Mon-Thursday by 1200

Test Code

NMCP036

Includes

Genes: NKX2-1; chr14q13.3

Preferred Specimen

Pediatric: lavender top EDTA minimum 3ml; Adult: lavender top EDTA minimum 6ml; Cord Blood: lavender top EDTA minimum 3 ml (maternal blood sample required)

Methodology
Bidirectional sequencing of the coding regions and intron-exon boundaries of NKX2-1; Multiplex ligation-dependent probe amplification (MLPA) for gene deletions

Report Available

"Sequencing: 2-3 weeks
MLPA: up to 4 weeks
"

Limitations

This test is offered as an automatic reflex to MLPA analysis if the sequencing assay does not detect a potential disease-causing mutation. NKX2-1 mutations are also associated with Choreoathetosis, Hypothyroidism, and Neonatal Respiratory Distress Syndrome (also known as Brain Lung Thyroid Syndrome).

Reference Range

Autosomal Dominant

Clinical Significance

"Benign Hereditary Chorea (BHC) is an autosomal dominant condition in which patients experience early onset (by 5 years), non-progressive or slowly progressive chorea. Dysarthria and gait abnormalities are also reported. Unlike patients with Huntington Disease, BHC patients do not develop dementia. Intelligence is normal to slightly below normal. BHC is heterogeneous, and not all families have been linked to chromosome 14 or the NKX2-1 gene. Identification of causative mutations in known or highly suspicious cases of BHC; rule-out inherited causes of chorea; diagnostic or presymptomatic testing of at-risk relatives of a proband; predictive prenatal testing when familial mutation is known. We were not able to locate any published series of patients with BHC who were evaluated for NKX2-1 mutations. Of reported mutations, 9 are point mutations and 1 is a gene deletion. Our combined sequencing and MLPA assay should detect all reported mutations. In a series of families undergoing linkage analysis, 3 of 7 families showed linkage to chromosome 14. Sequencing: Greater than 97% for nucleotides analyzed. All reports will indicate if a certain percentage of nucleotides were not called or were analyzed in a single direction.
MLPA: Analytical sensitivity for deletions is estimated to be at least 90%. "

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.