Amniotic Fluid Digestive Enzyme Analysis Is Useful for Identifying CFTR Gene Mutations of Unclear Significance.

Clin Chem. 2009 Oct 15. [Epub ahead of print]

Amniotic Fluid Digestive Enzyme Analysis Is Useful for Identifying CFTR Gene Mutations of Unclear Significance.

Oca F, Dreux S, Gérard B, Simon-Bouy B, de Becdelièvre A, Ferec C, Girodon E, Muller F.

Biochimie-Hormonologie, Hôpital Robert Debré, AP-HP, Paris, France.

BACKGROUND: The large number of CFTR [cystic fibrosis transmembrane conductance regulator (ATP-binding cassette sub-family C, member 7)] mutations and the existence of variants of unclear significance complicate the prenatal diagnosis of cystic fibrosis (CF). The aim of this study was to determine whether the pattern of amniotic fluid digestive enzymes (AF-DEs) could be correlated with the severity of CFTR mutations.

METHODS: The AF-DE pattern (gamma-glutamyltranspeptidase, aminopeptidase M, and the intestinal isoform of alkaline phosphatase) was retrospectively analyzed in 43 AF samples. All fetuses presented 2 CFTR mutations, which were classified according to the severity of the disease: CF/CF (n = 38); CF/CFTR-related disorders (n = 1); and CF/unknown variant (n = 4). The relationships between clinical CF status, CFTR mutations, and AF-DE pattern were studied.

RESULTS: Of 38 severely affected CF fetuses, an "obstructive" AF-DE pattern was observed in 15 of 15 samples collected before 22 weeks, irrespective of the CFTR mutation (diagnostic sensitivity, 100%; diagnostic specificity, 99.8%). In the 23 fetuses evaluated after 22 weeks, the AF-DE pattern was abnormal in 7 cases and noncontributive in 16 (diagnostic sensitivity, 30.4%; diagnostic specificity, 99.8%). Of the 5 questionable cases (F508del/N1224K, F508del/L73F, 3849+10kbC>T/G1127E, F508del/S1235R, F508del/G622D), all were CF symptom free at 2-4 years of follow-up. The AF-DE pattern (<22 weeks) was typical in 3 cases but abnormal in the last 2 cases.

CONCLUSIONS: AF-DE analysis is of value for prenatal CF diagnosis in classic forms of CF and could be helpful in nonclassic CF.

PMID: 19833837 [PubMed - as supplied by publisher]

Cystic fibrosis: defining a disease under-diagnosed in Pakistan

Trop Med Int Health. 2009 May;14(5):542-5.

Cystic fibrosis: defining a disease under-diagnosed in Pakistan.Shah U, Frossard P, Moatter T.Harvard Medical School Dubai Center, Dubai, UAE.Objective

Cystic fibrosis is frequently missed in the Pakistani population due to lack of appropriate diagnostic tools. Thus our aim was to define unknown disease-causing mutations to help create suitable diagnostic tests and improve understanding of what appears to be an aggressive and under-diagnosed disease in this population.

Methods Patients with elevated sweat chloride values and clinically suspected CF were recruited from Aga Khan University, Pakistan. Mutations DF508, S549R, S549N, Y569D, 296 + 12(T>C), G553X, G551D and G551X were screened for by allele specific polymerase chain reactions. CFTR exons 10, 11 and 12 were sequenced by direct DNA sequencing.

Results Of 150 patients tested by PCR, 26 (17.3%) were positive for DeltaF508. One patient was a F508/S549N compound heterozygote. Eighty-three of 87 patients sequenced for mutations in exon 10 were normal; 42/43 for exon 11 and 29 for exon 12 were normal.

Conclusion This first step in defining mutations involved in Pakistani CF suggests that DeltaF508 is uncommon and S549 was the only additional mutation identified in CFTR exons 10, 11 and 12. Identification of the remaining mutations and their frequency is required to design appropriate tests and improve understanding and management of the disease.

PMID: 19645745 [PubMed - in process]

Lung Disease at Diagnosis in Infants with Cystic Fibrosis Detected by Newborn Screening.

Lung Disease at Diagnosis in Infants with Cystic Fibrosis Detected by Newborn Screening.

http://snipurl.com/g5wuv

Sly PD, Brennan S, Gangell C, de Klerk N, Murray C, Mott L, Stick SM, Robinson PJ, Robertson CF, Ranganathan SC.

Division of Clinical Sciences, Telethon Institute for Child Health Research and Centre for Child Health Research , University of Western Australia, Perth, Western Australia, Australia; Department of Respiratory Medicine, Princess Margaret Hospital for Children, Perth, Western Australia, Australia.

RATIONALE: The promise of newborn screening (NBS) for cystic fibrosis (CF) has not been fully realised, with improvement in respiratory outcomes unclear. We hypothesised that significant lung disease was present at diagnosis.

OBJECTIVES: To determine the extent of lung disease in a geographically-defined population of infants with CF diagnosed following detection by NBS.

METHODS: Fifty seven infants (median age 3.6 months) with CF underwent bronchoalveolar lavage (BAL) and chest computed tomography (CT) using a 3-slice inspiratory and expiratory protocol.

MAIN RESULTS: Despite the absence of respiratory symptoms in 48 (84.2%), a substantial proportion of infants had lung disease with: bacterial infection detected in 12 (21.1%), including S. aureus (n=4) and P. aeruginosa (N=3); neutrophilic inflammation (41.4 x10(3) cells/ml representing 18.7 % of total cell count); pro-inflammatory cytokines with 44 (77.2%) having detectable IL-8 ; and 17 (29.8%) having detectable free neutrophil elastase (NE) activity. Inflammation was increased in those with infection and respiratory symptoms however the majority of those infected were asymptomatic. Radiological evidence of structural lung disease was common with 46 (80.7%) having an abnormal CT; 11 (18.6%) had bronchial dilatation, 27 (45.0%) had bronchial wall thickening and 40 (66.7%) had gas trapping. On multivariate analysis free NE activity was associated with structural lung disease. Most children with structural lung disease had no clinically-apparent lung disease.

CONCLUSIONS: These data support the need for full evaluation in infancy and argue for new treatment strategies, especially those targeting neutrophilic inflammation, if the promise of NBS for CF is to be realised.