Multiplex Ligation-Dependent Probe Amplification Improves the Detection Rate of NKX2.1 Mutations in Patients Affected by Brain-Lung-Thyroid Syndrome

Abstract

Background: NKX2.1 mutations have been identified in patients displaying complete or partial brain-lung-thyroid syndrome, which can include benign hereditary chorea (BHC), hypothyroidism and/or lung disease. Aims and Methods: We evaluated the recently developed Multiplex Ligation-dependent Probe Amplification (MLPA) method to assess the relative copy number of genes. The goal was to determine if MLPA could improve, in addition to direct sequencing, the detection rate of NKX2.1 mutations in a phenotype-selected cohort of 24 patients affected by neurological, thyroid and/or pulmonary disorders. Results: Direct sequencing revealed two heterozygous mutations. Using MLPA, we identified two further heterozygous NKX2.1 gene deletions. MLPA increased the detection rate by 50%. All patients with gene deletions identified were affected by BHC and congenital hypothyroidism. Conclusion: MLPA should be considered as a complementary tool in patients with partial or total brain-lung-thyroid syndrome when direct sequencing failed to identify NKX2.1 mutations. All patients with an NKX2.1 mutation had BHC and congenital hypothyroidism, emphasizing the high prevalence of these signs associated with defective NKX2.1 alleles.