Multiplex Ligation-dependent Probe Amplification improves the detection rate of NKX2.1 mutations in patients affected by brain-lung-thyroid syndrome.

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.

Quantitative lung perfusion scan as a predictor of aerosol distribution heterogeneity and disease severity in children with cystic fibrosis.

BACKGROUND: The assessment of lung ventilation by radionuclide imaging has proved useful for the optimization of aerosol therapy in children with cystic fibrosis. Further analysis of lung perfusion may provide additional information. METHODS: Quantitative analysis of regional lung aerosol distribution (Tc phytates) and perfusion (Tc macroaggregates) homogeneity was performed in 18 children with cystic fibrosis, using the third and fourth spatial moments (skew and Kurtosis) of count distribution. Patients were chosen from a prospective study whose goal was to compare the efficacy of two nebulization methods of a radiolabelled aerosol: one session involved a nebulizer activated by patient inspiratory flow (control session), whereas the other involved a nebulizer powered by a pressure support device (PS session). RESULTS: Quantitative regional distribution of perfusion was similar to aerosol distribution, although skew and Kurtosis were lower, indicating better homogeneity. Perfusion skew was inversely correlated with pulmonary volumes and Shwachman score, even more significantly than ventilation skew. Using receiver operating characteristic curve analysis, a perfusion skew threshold of 0.67 was predictive of disease severity (FEV1 > or =60% or FEV1 <60%) with 86% sensitivity and 91% specificity. Furthermore, same skew threshold allowed the identification of patients who were 'PS responders' (greater amount of radioactivity deposited after the PS session) or 'PS non-responders' with 80% sensitivity and 77% specificity. CONCLUSION: Quantification of regional lung perfusion is easy to perform and heterogeneity of the distribution is closely correlated to disease severity. Moreover, perfusion skew can identify patients who are likely to benefit from pressure support (to optimize aerosol therapy) and may be helpful for orienting potential non-responders towards alternative therapies.