Phenotypic discordance in three siblings affected by atypical cystic fibrosis with the F508del/D614G genotype.
ABSTRACT We report an example of atypical CF, i.e., a family in which three siblings were affected by late-diagnosed mild CF, and showed discordant pulmonary and pancreatic phenotypes. Sibling no. 1 (male), showed a severe pulmonary involvement and pancreatic sufficiency; sibling no. 2 (female) showed a mild pulmonary disease with pancreatic sufficiency; sibling no. 3 (male) had a very mild pulmonary expression and pancreatic insufficiency. The sweat test was altered in all three siblings, and all had intestinal occlusion in young age. The whole scanning of CFTR revealed the rare F508del/D614G genotype. The discordance of clinical expression within the same family reinforces the putative role of modifier genes of CF phenotype.
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ABSTRACT: Many Cystic Fibrosis (CF) carriers have been detected testing some subjects with chronic pancreatitis for a limited number of mutations. The aim of this study was to find out if some subjects with pancreatitis and a CFTR mutation actually carry another, undetected mutation. We screened for 18 CFTR mutations plus the CFTR intron 8 poly(T) tract length a population of 67 patients suffering from idiopathic either acute, or recurrent acute, or chronic pancreatitis. Three of them were diagnosed as affected by CF. Among the others, a subset of 14 (8 CFTR mutation carriers, 4 5T carriers, and 2 sweat chloride borderliners) was selected and analyzed by denaturing gradient gel electrophoresis. Six possibly CF-related mutations were detected: L997F and 3878delG were found in two of the subjects already carrying another mutation, S1235R and L997F in one patient carrying the 5T, and L997F and D614G in the two patients with borderline sweat chloride. Among the 14 selected cases a total of 11 patients carried at least one mutation, and three of them were compound heterozygotes. Though it is debatable whether these three individuals can be considered affected by CF, their pancreatitis is possibly a clinical manifestation of some CFTR-related disease. Hum Mutat 18:166, 2001.Human Mutation 09/2001; 18(2):166. · 5.21 Impact Factor
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ABSTRACT: An analysis of 274 non-delta F508 Italian cystic fibrosis chromosomes was carried out to determine their molecular defect. In a first step, the delta F508 and 59 other mutations were detected by polyacrylamide gel electrophoresis, restriction digestion, and the amplification refractory mutation system (ARMS) technique. The molecular defects of the other chromosomes were screened for by denaturing gradient gel electrophoresis analysis of exons 3, 4, 7, 11, 12, 13, 14a, 17b, 19 and 20. Direct sequencing was carried out if necessary. This approach allowed us to identify 3 novel mutations, namely M348K, D614G and F693L.Human Heredity 01/1993; 43(5):295-300. · 1.57 Impact Factor
- Cell 08/1993; 73(7):1251-4. · 31.96 Impact Factor
Phenotypic discordance in three siblings affected by atypical cystic
fibrosis with the F508del/D614G genotype
Giuseppe Castaldoa,b,*, Rossella Tomaiuolob, Borghina Vanacoreb,
Pietro Ferrarac, Stefania del Vecchioc, Vincenzo Carnovalec,
Pasquale Abetec, Franco Rengoc, Francesco Salvatoreb
aUniversita ` del Molise Facolta ` di SS MM FF NN Via Mazzini 86170 Isernia Italia
bCEINGE Biotechnologie Avanzate scarl Via Comunale Margherita 482 80145 Napoli Italia
cDepartment of Clinical Medicine, Cardiovascular and Immunological Sciences Adult Unit Campania Regional Cystic Fibrosis Center, Naples, Italy
Received 30 November 2005; received in revised form 30 November 2005; accepted 1 December 2005
Available online 14 February 2006
We report an example of atypical CF, i.e., a family in which three siblings were affected by late-diagnosed mild CF, and showed
discordant pulmonary and pancreatic phenotypes. Sibling no. 1 (male), showed a severe pulmonary involvement and pancreatic sufficiency;
sibling no. 2 (female) showed a mild pulmonary disease with pancreatic sufficiency; sibling no. 3 (male) had a very mild pulmonary
expression and pancreatic insufficiency. The sweat test was altered in all three siblings, and all had intestinal occlusion in young age. The
whole scanning of CFTR revealed the rare F508del/D614G genotype. The discordance of clinical expression within the same family
reinforces the putative role of modifier genes of CF phenotype.
D 2005 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.
Keywords: Cystic fibrosis; Genotype–phenotype correlation; Late diagnosis mild CF
1. Case reports
Patient 1: A 46-year-old male (current age) was referred to
our Centre 5 years ago because of CBAVD and
bronchiectasis. He was born to unrelated parents
from Southern Italy. He underwent appendectomy
at the age of 10 years for intestinal occlusion, and
had experienced several episodes of pulmonary
worsening. At admission, sweat chloride was 79
mEq/L and sweat sodium was 70 mEq/L (cut-off
levels: 60 mEq/L). Imaging evaluation confirmed
a chronic severe bronchopneumopathy with bron-
chiectasis, and the sputum culture was positive to
and 51% of predicted, respectively, indicating
moderate pulmonary involvement . The patient
was pancreatic-sufficient and did not report
episodes of pancreatitis. He is affected by glucose
by ultrasound (US) scanning and laboratory is
normal. Molecular analysis revealed the F508del
CF was diagnosed, the patient was colonised by
Pseudomonas aeruginosa and then by Achromo-
bacter spp. Sporadic presence of Burkholderia
cepacia, Stenotrophomonas maltophilia and Aci-
netobacter spp. in the sputum culture were also
recorded, as well as an episode of allergic
bronchopulmonary aspergillosis (ABPA).
After CF was diagnosed in patient no. 1, we
counseled family members, and they agreed to
undergo molecular analysis for carrier detection.
The analysis revealed the F508del mutation in a
brother and in a sister of patient. Surprisingly,
1569-1993/$ - see front matter D 2005 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.
* Corresponding author.
E-mail address: email@example.com (G. Castaldo).
Journal of Cystic Fibrosis 5 (2006) 193 – 195
CF; hence, they were referred to our Centre. The
gene sequencing scanning of the whole coding
region of the CFTR gene in the three siblings
revealed the second mutation, i.e., D614G. Thus,
the CFTR genotype was F508del/D614G.
Patient 2: This 44-year-old (current age) female underwent
appendectomy because of intestinal occlusion at
the age of 16 years; she has smoked cigarettes
since she was 13 years old (about 20 cigarettes/
day). At our evaluation, the sweat analysis
showed chloride levels of 55 mEq/L and sodium
levels of 71 mEq/L. Pulmonary radiographic
evaluation showed a mild chronic bronchop-
neumopathy with rare bronchiectasis. FVC and
FEV1 were 80% and 84% of predicted, respec-
tively. She was pancreatic-sufficient and did not
report any episode of pancreatitis. Liver function,
as evaluated clinically, by US scanning and
laboratory is normal. She is not affected by
glucose intolerance. She is infertile, and under-
went several cycles of in vitro fertilization and
embryo transfer with no pregnancy outcome.
During the 3 years since CF was diagnosed, she
had a single episode of acute pulmonary infection
by P. aeruginosa with haemoptysis. Two years
ago, she had a breast carcinoma, which was
treated by surgery followed by chemotherapy.
Patient 3: 35-year-old (current age) male. At the age of
7 years, he underwent appendectomy because of
intestinal occlusion. He had nasal polypectomy at
the age of 16 years. He has smoked cigarettes
since he was 15 years old (about 20 cigarettes/
day). Upon admission to our Centre (3 years ago),
the sweat test showed chloride levels of 97 mEq/L
and sodium levels of 73 mEq/L. The imaging
evaluation demonstrated a mild chronic bron-
chopneumopathy. FVC and FEV1 were 99% and
(reverted by pancreatic supplementation) and was
pancreatic insufficient as evaluated by the stea-
tocrit. During the last 3 years, the patient had one
episode of ABPA. There was no glucose
intolerance. Liver function was normal. In the
last 6 months he had one episode of acute
pulmonary infection by S. aureus. Clinical find-
ings and US scanning demonstrated CBAVD.
Noone and Knowles  have reviewed the phenotypes
associated with ‘‘atypical’’ CF, which includes CBAVD in
males, mild pulmonary expression with bronchiectasis and
possible colonisation by P. aeruginosa, idiopathic chronic
pancreatitis, sinusitis, allergic bronchopulmonary aspergil-
losis and asthma. In most atypical CF patients, only one of
these symptoms is present and the onset of symptoms is late.
Sweat chloride is typically normal or borderline, and the
CFTR genotype includes at least one mild CF mutation that
is dominant over the severe mutation present on the other
allele . Although the three cases reported herein can be
classified ‘‘atypical’’ CF, the phenotypic discordance among
the three siblings, and the presence of several symptoms in
each sibling warrant some comments (Table 1).
The sweat levels of chloride were borderline in sibling
no. 2 and altered in the other two siblings. Consequently, we
should be aware that sweat chloride levels in atypical CF
may be normal, borderline or altered. Indeed, the three
siblings carried the F508del/D614G genotype. D614G [5,6]
is a rare mutation, not included in commercial kits or in
home-made panels . It is associated with aberrant
processing and residual activity of the CFTR chloride
channel . The D614G mutation has been identified in
atypical CF patients with idiopathic pancreatitis [5,6]. Our
report confirms its ‘‘mild’’ character and association with the
atypical CF phenotype.
Clinical expression in the three siblings affected by atypical cystic fibrosis
Sibling 1 Sibling 2Sibling 3
Age at diagnosis
46 years old, male
40 years old
44 year old, female
40 years old
35 year old, male
Severe chronic pneumopathy with bronchiectasis
Mild chronic bronchopneumopathy
Mild chronic bronchopneumopathy
88 FEV1% of predicted
Pancreatic expressionPancreatic sufficiencyPancreatic insufficiency
G. Castaldo et al. / Journal of Cystic Fibrosis 5 (2006) 193–195
Once a patient with atypical CF has been identified,
siblings should undergo molecular analysis to exclude other
cases of atypical CF, which can be associated with very mild
expression, as in the case of our siblings 2 and 3. However,
given the different epidemiology of CFTR mutations
between classical and atypical CF, and the myriad of rare
mutations identified in the latter group, atypical CF may
elude small panels of mutations [2,4]. This suggests that
gene scanning procedures (i.e., direct sequencing, DGGE,
DHPLC) should be used in suspected cases of atypical CF.
Furthermore, given the presence of a severe mutation in
most atypical CF patients, each sibling has a 1:2 risk of
carrying the severe mutation. Consequently, given the 1:25
frequency of CF carriers in the general population, each
carrier has a 1:100 a priori risk of generating children with
the classical, severe form of CF. Molecular analysis and
genetic counseling of the families may contribute to
The pulmonary expression differed in the three siblings,
being more severe in patient no. 1 than in the other two
siblings, although both were smokers. It cannot be excluded
that the pulmonary expression may become more severe in
siblings 2 and 3 (both younger than sibling 1). However, our
finding is in agreement with reports of discordance in the
pulmonary expression of CF in patients bearing the same
CFTR genotype  and in CF siblings , and confirms
that modifier genes play a major role in the CF pulmonary
phenotype . There was also discordance between the
three siblings also in terms of the pancreatic expression of
the disease. Patient nos. 1 and 2 are pancreatic sufficient;
sibling 3 is pancreatic insufficient. The discordance of the
pancreatic status is surprising, since the pancreatic expres-
sion of CF is usually strictly related to the CFTR genotype
. Finally, two of the three siblings had ABPA, and only
patient no. 1 was affected by glucose intolerance. All three
siblings had undergone appendectomy because of intestinal
occlusion. Therefore, also intestinal occlusion in young age
and appendectomy in more siblings of a family should alert
the physician to the possibility of atypical CF. Finally, all
three siblings were sterile (the two males because of
CBAVD), and this report confirms that CBAVD is strongly
suggestive of atypical CF.
To conclude, the atypical forms of CF may feature a
constellation of symptoms, some of which (intestinal
occlusion) are not usually associated with atypical CF.
The variability among the siblings of our study reinforces
the concept that modifier genes are involved in the
phenotypic expression of CF. Molecular analysis, based
on the scanning of the CFTR gene, plays a relevant role in
the diagnosis of atypical CF.
Grants from Ministero della Salute (L. 362/99), MIUR
(FIRB 2001 and PRIN 2002), Universita ` del Molise and
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