Clericuzio-Type Poikiloderma With Neutropenia Syndrome in Three Sibs With Mutations in the C16orf57 Gene: Delineation of the Phenotype

Article (PDF Available)inAmerican Journal of Medical Genetics Part A 152A(10):2588-94 · October 2010with153 Reads
DOI: 10.1002/ajmg.a.33600 · Source: PubMed
Abstract
We report on three sibs who have autosomal recessive Clericuzio-type poikiloderma neutropenia (PN) syndrome. Recently, this consanguineous family was reported and shown to be informative in identifying the C16orf57 gene as the causative gene for this syndrome. Here we present the clinical data in detail. PN is a distinct and recognizable entity belonging to the group of poikiloderma syndromes among which Rothmund-Thomson is perhaps the best described and understood. PN is characterized by cutaneous poikiloderma, hyperkeratotic nails, generalized hyperkeratosis on palms and soles, neutropenia, short stature, and recurrent pulmonary infections. In order to delineate the phenotype of this rare genodermatosis, the clinical presentation together with the molecular investigations in our patients are reported and compared to those from the literature.
CLINICAL REPORT
Clericuzio-Type Poikiloderma With Neutropenia
Syndrome in Three Sibs With Mutations in the
C16orf57 Gene: Delineation of the Phenotype
D. Concolino,
1
* G. Roversi,
2,3
G.L. Muzzi,
1
S. Sestito,
1
E.A. Colombo,
2
L. Volpi,
4
L. Larizza,
2
and P. Strisciuglio
5
1
Dipartimento di Pediatria, Universit
a ‘‘Magna Graecia,’’ Catanzaro, Italy
2
Genetica Medica, Dipartimento Medicina, Chirurgia e Odontoiatria, Universit
a degli Studi di Milano, Milano, Italy
3
Unit
a di Genetica Medica, Fondazione IRCCS, Istituto Nazionale Tumori, Milano, Italy
4
Dipartimento di Biologia e Genetica per le Scienze Mediche, Universit
a degli Studi di Milano, Milano, Italy
5
Indirizzo attuale: Dipartimento di Pediatria, Universit
a ‘‘Federico II’’, Napoli, Italy
Received 19 September 2009; Accepted 24 May 2010
We report on three sibs who have autosomal recessive Clericuzio-
type poikiloderma neutropenia (PN) syndrome. Recently, this
consanguineous family was reported and shown to be informa-
tive in identifying the C16orf57 gene as the causative gene for this
syndrome. Here we present the clinical data in detail. PN is a
distinct and recognizable entity belonging to the group of
poikiloderma syndromes among which RothmundThomson is
perhaps the best described and understood. PN is characterized
by cutaneous poikiloderma, hyperkeratotic nails, generalized
hyperkeratosis on palms and soles, neutropenia, short stature,
and recurrent pulmonary infections. In order to delineate the
phenotype of this rare genodermat osis, the clinical presentation
together with the molecular investigations in our patients are
reported and compared to those from the literature.
2010 Wiley-Liss, Inc.
Key words: poikiloderma; genodermatosis; congenital neutropenia
INTRODUCTION
Clericuzio-type poikiloderma with neutropenia (PN OMIM
#604173) represents a well-defined phenotype characterized by
In this article Concolino and colleagues describe the phenotype in
three sibs with the Clercuzio-type poikiloderma with neutropenia
syndrome (PN). Most of the authors are also co-authors on the
article by Volpi et al. published in the January issue of the
American Journal of Human Genetics where the causative gene for
PN is identified in this family. In the ensuing report herein
Concolino et al. provide comprehensive phenotypic data on the
sibs who were succinctly presented in the AJHG paper. Continuing
on this theme, I would turn the reader’s attention to a related
article on this topic by Tanaka and colleagues, published in the
June issue of the Journal [Tanaka et al., 2010. Identification of a
homozygous deletion mutation in C16orf57 in a family with
Clericuzio-type poikiloderma with neutropenia, Am J Med Genet
Part A 152A:1347–1348] where the authors identify a homozygous
deletion in sibs previously reported in the Journal in 2008.
John C. Carey
Editor-in-Chief
Editor’s Note
Grant sponsor: Nando Peretti Foundation; Grant number: 2007/14; Grant
sponsor: Associazione Italiana per la Ricerca sul Cancro (AIRC); Grant
number: 20082009/4217.
*Correspondence to:
D. Concolino, M.D., Department of Pediatrics, University ‘‘Magna
Graecia’’ of Catanzaro, c/o Ospedale Civile ‘‘A. Pugliese,’’ Viale Pio X,
88100 Catanzaro, Italy. E-mail: dconcolino@unicz.it
Published online 23 August 2010 in Wiley Online Library
(wileyonlinelibrary.com).
DOI 10.1002/ajmg.a.33600
How to Cite this Article:
Concolino D, Roversi G, Muzzi GL, Sestito S,
Colombo EA, Volpi L, Larizza L, Strisciuglio
P. 2010. Clericuzio-type Poikiloderma with
neutropenia syndrome in three sibs with
mutations in the C16orf57 gene: Delineation
of the phenotype.
Am J Med Genet Part A 152A:25882594.
2010 Wiley-Liss, Inc. 2588
poikiloderma, hyperkeratotic nails, generalized hyperkeratosis
on palms and soles, neutropenia, short stature, and recurrent
pulmonary infections [Clericuzio et al., 1991].
The dermatologic onset consists of the occurrence of a papular
erythematous rash during the first months of life that spreads on to
the limbs centrifugally. When the papulae vanish, hypo/hyper
pigmentation and telangiectasia develop.
The differential diagnosis includes other poikiloderma condi-
tions, that is, RAPADALINO and RothmundThomson syn-
dromes (RTS, OMIM #268400) [Van Hove et al., 2005]. Due
to the overlap of some distinctive clinical features, PN patients
may be misdiagnosed as RTS, even if cataract and digestive tract
involvement (hallmark features of RTS) are not preset. In PN
patients chronic neutropenia is a distinguishing manifestation. At
the molecular level RECQL4 helicase gene mutations are present in
about 6065% of RTS cases [Larizza et al. , 2010] but are not present
in all PN patients, strengthening the hypothesis of distinct genetic
mechanism responsible for PN [Wang et al., 2003; Van Hove et al.,
2005; Mostefai et al., 2008]. Recently, we demonstrated that muta-
tions in the C16orf57 gene are responsible for the PN phenotype in
the reported three sibs [Volpi et al., 2010]. In this report we present
the clinical data in more detail.
The sibs hip reported underlines the intrafamilial variable
expressivity and the natural history of PN syndrome. Moreover,
we compare the clinical features in our patients with the 11 so far
published [Pianigiani et al., 2001; Wang et al., 2003; Van Hove et al.,
2005; Mostefai et al., 2008] to better delineate the spectrum of this
rare syndrome.
CLINICAL REPORTS
Family history and genetic testing: Three siblings, one male
(Patient 1) and two females (Patients 2 and 3), from healthy
consanguineous (Fig. 1) Italian parents were born at term after
uneventful pregnancy, absence of perinatal problems; all growth
parameters were in the normal range. At birth none showed skin
manifestations and/or dysmorphic signs. As shown in the simpli-
fied pedigree (Fig. 1) [see full pedigree, Volpi et al., 2010] the
siblings are born to double second cousins, and the father himself is
son of a consanguineous marriage.
Patient 1
The cutaneous manifestations began at 6 months of age as a rash
involving primarily the cheeks, extensor surface of the arms, and
then the knees (Fig. 1, V2). During his first months of life the child
had recurrent pulmonary infections, otitis media, and sinusitis
until the age of 3 years. He showed poor growth starting in infancy
but no delay in psychomotor development. Skin findings including
reticular pattern of hyper- and hypopigmentation with slight
telangiectasia and atrophy of his cheeks, upper trunk, and extremi-
ties, allowed a clinical diagnosis of RTS at the age of 5 years. At the
age of 6 years because of a pulmonary infection he was hospitalized
and at that time he showed a weight of 17.7 kg (10th centile), a
height of 106 cm (3rd centile), and normal mental development.
During hospitalization the biological data as laboratory inves-
tigations showed leukopenia (2.5 10
3
mL) with neutropenia
(700 mm
3
), increased creatine phosphokinase (CPK, 250 U/L,
n.v. < 180), and lactate dehydrogenase (LDH, 700 U/L, n.v. < 500)
while viral serology, erythrocyte sedimentation rate, C reactive
protein, immunoglobulin subclasses (IgA, IgM, IgG), complement
factors (C3 and C4), AGA, EMA, tTG, and thyroid hormones were
in the normal range for age. Bone marrow smears showed abnormal
maturation of neutrophil line age, with increased numbers of
immature cells, but no abnormal clonality. The skeletal investiga-
tion, electromyography, electroencephalography, abdominal ultra-
sonography, echocardiography, and bone scintigraphy with Tc99m
were normal. No ophthalmologic abnormality and specifically no
cataracts were found.
The patient came to our attention for the first time at the age of
17 years and though a history of persistent neutropenia was
reported, no recent infectious episodes were recorded. At that
time his weight was 49 kg (<5th centile), his height 156 cm
(<3rd centile), his head circumference 56 cm (50th centile),
and Tanner stage was P5B5. Until age 3 years, growth velocity had
always been under 5th centile; his genetic target for the height was
170 8 cm. Puberty had begun at age 14 years without pubertal
growth spurt.
The clinical exam at the age of 21 (Fig. 2) showed dysmorphic
signs including eyebrows hypoplasia with normal hair, frontal
bossing, widely spaced eyes without telecanthus, midface hypopla-
sia, small nose with depressed nasal bridge, and mild prognathism.
Generalized fine hyperkeratosis with poikilo derma on the face and
arms with several areas of skin atrophy was detected. Hyperkerato-
sis was more pronounced at extremities, with hyperkeratotic palms/
soles and pachyonychia. A bilateral hyperlaxity of fingers (Fig. 2)
and a joint stiffness in elbows were present.
The skin biopsy showed edema in the papillary derma, necrosis
of keratinocytes with apoptosis, acute perivascular inflammation
with granulomatous vasculitis of derma middle blood vessels.
Standard karyotype on skin biopsy was normal. No screening for
increased breakage was performed. No bone abnormalities were
found. Skeletal X-rays were normal, and MRI showed normal
intensity of medullar bone signal of explore d segments. The bone
age was appropriate for chronological age.
FIG. 1. Pedigree of the family.
CONCOLINO ET AL. 2589
FIG. 2. Patient 1 at the age of 21 years. Note eyebrows hypoplasia, severe midface hypoplasia, the pattern of the poikiloderma, pachyonychia and
plantar hyperkeratosis, hypermobile fingers.
2590 AMERICAN JOURNAL OF MEDICAL GENETICS PART A
The mental development was normal. Mild splenomegaly was
detected by abdominal ultrasonogra phy. Laboratory investiga-
tions showed a leukopenia (GB 2.2 10
3
mL) with neutropenia
(550 mm
3
), elevated LDH (800 U/L, n.v. < 500), and CPK (280 U/
L, n.v. < 180).
Patient 2
The skin manifestations appeared at 8 months of age with a rash
involving primarily the face and the extensor surface of the arms
evolving in classic poikiloderma (Fig. 1, V4). During the first
years of life no history of recur rent infections was reported but
neutropenia was found at the age of 2 years. At the age of 3 years she
showed a reduction of height velocity with a height age of 2 years.
At age 4 a high-resolution cytogenetic analysis confirmed a 46,XX
karyotype.
When she first came to our attention at the age of 9 years and
11 months; the clinical examination showed a weight of 25 kg (10th
centile), a height of 120 cm (<3rd centile), a head circumference of
52 cm (50th centile), prepubertal stage and mental development
were normal. Exam showed poikiloderma on the face, arms, and
thorax, nail dystrophy, hypoplasia of eyebrows, mild midface
hypoplasia, and mild splenomegaly (Fig. 3). She showed leukopenia
(3.5 10
9
mL) with neutropenia (600 mm
3
). CPK and LDH were
elevated. Viral serology, AGA, EMA, tTG, were normal. Normal
levels of all immunoglobulin classes and of complement factors
(C3 and C4) were found. Renal and cardiac functions were normal.
Electromyography, electroenc ephalography, and bone scintigra-
phy with technetium were normal. Abdominal ultrasonography
showed a spleen size of 16 cm.
Physical examination at the age of 16 years showed
midface hypoplasia with a small mandible, hypoplasia of lateral
eyebrows, hypertelorism (interpupillar distance >95th centile),
long philtrum, hypermobile fingers with ‘‘beak of swan’’ appe ar-
ance (Fig. 3b).
Patient 3
The child was evaluated at our hospital at the age of 8 years and 8
months (Fig. 1, V5). She showed the characteristic poikiloderm-
atous rash that had first appeared at age 10 months as a facial rash.
The rash was erythematous and macular with few atrophic areas.
During the first months of life the girl had recurrent pulmonary
infections, otitis media, and sinusitis until 3 years of age.
Leukopenia (3.2 10
3
mL) was found with severe neutropenia
(0.6 10
3
mL) at age 18 months. The short stature was discovered
at the age of 3 years and her growth velocity was always under 5th
centile in the following years. High-resolution karyotype was
46,XX.
Clinical examination showed a weight of 23 kg (1025th centile),
a height of 121.5 cm (<3rd centile), a head circumference of 52 cm
(5070th centile), prepubertal stage, and mental development were
normal. The patient showed poikiloderma, microretrognathism,
and a low posterior hairline (Fig. 4a). At the age of 12 years a
dysmorphic examination revealed lateral hypoplasia of eyebrows,
hypoplasia alae nasal, mild retromicrognatia, and hypermo bile
fingers with ‘‘beak of swan’’ appearance (Fig. 4b).
The routine laboratory investigations showed increased CPK
and LDH, leukopenia (GB 3.2 10
3
mL) with marked neutropenia
(500 mm
3
). Levels of immunoglobulin classes and complement
factors (C3 and C4) were normal. Abdominal and cardiac ultraso-
nography, electromyography, and muscular biopsy (histochemical
and biochemi cal analyses) were normal.
FIG. 3. Patient 2: (a) at the age of 10 years: note poikiloderma of face and arms and foot pachyonychia and (b) at the age of 16 years: note a mild
midface hypoplasia with a small mandible, hypoplasia of lateral eyebrows, hypertelorism, long philtrum, hypermobile fingers with ‘‘beak of swan’’
appearance.
CONCOLINO ET AL. 2591
In both sisters the bone age matched the chronological age and
endocrine exams showed that IGF1 and IGFBP3 levels, arginine/
L-dopa-stimulated growth hormone analysis, TSH, and T3 levels
were in the normal range. The growth velocity was between 5 and
10th centile and the puberty started at the age of 11 and 12 years,
respectively, without pubertal spurt. Their genetic target was
157 8 cm.
At the 6-month follow-up, evaluation of the patients’
neutropenia found a persistent neutropenia with a mean value of
700 mm
3
(range of 5001,100 mm
3
). Bone marrow smears showed
myelodysplastic features, abnormal maturation of neutrophil
lineage, and an increased number of immature cells. None of
the three patients showed skin sensitivity to sun exposure and
there were no evidence of cancer skin lesions. None of them
developed cataracts.
To exclude a possible diagnosis of RTS, the RECQL4 gene was
capillary sequen ced in the propositus, Patient 1, and no mutations
were found in all exons and introns, in keeping with the finding that
the three affected sibs do not share intragenic RECQL4 SNPs (data
not shown). Autozygosity mapping performed by a genome-wide
SNP array from 18 family members identified a candidate region of
3.4 Mb map ping at 16q inherited identically by descent (IBD) in all
affected family members. Next gen eration sequencing of the entire
repeats-masked candidate region, including coding and noncoding
sequence, revealed a homozygous change at IVS IV donor splice site
of the C16orf57 gene. Details of the multimethod procedure used
to hunt and validate the causative gene have been reported [Volpi
et al., 2010].
DISCUSSION
We report on the clinical features of three siblings affected with
Clericuzio poikiloderma with neutropenia syndrome, all carrying
the same homozygous c.504-2A > C mutation at the acceptor splice
site of intron 4 of C16orf57 gene [Volpi et al., 2010]. Our molecular
data conclusively confirm the notion that this rare poikiloderm a
syndrome is a genetically distinct entity [Van Ho ve et al., 2005;
Mostefai et al., 2008].
Since the first description by Clericuzio in 14 Navajo Indians
[Clericuzio et al., 1991], 5 other kindreds have been described
[Wang et al., 2003; Van Hove et al., 2005; Mostefai et al., 2008]
with a total of 10 affected subjects, coming from different countries
(2 Navajo, 1 Turkish/British, 2 Scottish, 2 Turkish, and 3
Moroccan). All reported patients, including ours, had a clinical
diagnosis of PN and absence of RECQL4 mutations. Moreover, an
Italian patient, first reported as RTS and myelodysplasia [Pianigiani
et al., 2001] but displayed a typical PN phenotype , was found to
be a compound heterozygote for C16orf57 mutations (c.502A > G
and c.666-676 þ 1del12) [Volpi et al., 2010]. This confirms that
PN is a genetic disease likely occurring in all ethnicities and not
restricted to the American Navajo population [Erickson, 1999].
We compared the phenotype of our affected sibs with that of
previously described patients (Table I) including the first patients
who have been molecularly assessed to delineate the spectrum of
clinical findings. We suggest that this description may be helpful to
recruit and select patient candidates to be tested for the C16orf57
gene.
With regard to RTS, which enters in the differential diagnosis
with PN, we underline the differential profile of the skin changes;
they start in both syndromes in the first year of life with the same
morphology and evolution of the lesions (from acute rash to
chronic poikiloderma with prevalent acral distribution). Peripheral
involvement of arms and legs at the onset, then spreading centrifu-
gally has been described in most of the previously PN reported cases
[Van Hove et al., 2005]. This observati on has led to an emphasis on
the initial localizati on of the rash as one of the main differential
hallmarks between PN and RTS, where the rash starts on the face
[Wang et al., 2003; Van Hove et al., 2005]. In our patients the skin
FIG. 4. Patient 3: (a) at the age of 8 years: note face poikiloderma. b: At the age of 12: note eyebrows hypoplasia, mild retromicrognatia, hypermobile
fingers with ‘‘beak of swan’’ appearance.
2592 AMERICAN JOURNAL OF MEDICAL GENETICS PART A
TABLE I. Clinical and Laboratory Findings in 14 Patients With Poikiloderma Neutropenia Syndrome
Present report
(one kindred)
Mostefai et al.
[2008]
(one kindred)
Van Hove et al.
[2005]
(one kindred)
Wang et al. [2003]
(three kindreds)
Pianigiani et al.
[2001]
(one kindred)
Ethnicity
Italian Moroccan Turkish Navajo
Turkish/
British Scottish Italian
1231 2 3 12121 12 1
Skin manifestations
Age onset 6mo 8mo 10mo 14mo 15d 6mo 8mo 11mo / / 3mo 2mo 2mo 67mo
Initial localization Cheeks Face Face Face,
extremities
Face,
extremities
Face,
extremities
Arms, legs / / / Lower
extremities
Arms, legs Arms, legs /
Pachyonychia þþþþ þ þþþþþ þþ þ
Growth delay þþ þ þ þ (3y) þþ (3y) / /// / / / þ
Dysmorphic features þþþ ///////// þ
Recurrent infections
Pneumonia þþþ þ þ þþþþ/ þþ þ
Otitis media þþ þ þ þþþþ/ þþ þ
Other S FC; A A BL GS BL; CO / / / / / GS
Neutropenia
Age onset 6mo 2y 18mo 14mo 12mo 6mo 7d 21d / / 20mo 20mo 20mo /
Absolute number
(mm
3
)
5001,100 600 800 350700 220884 3451,541 1835,200 150500 / / / 300 100900 100900 355
Laboratory findings
CPK þþ/ ///þ// / / / /
LDH þþþ ///þþ// / / / /
Splenomegaly þþþ þ þ þþ// / / / þ
/, not reported; , absent; þ, present; S, sinusitis; FC, facial cellulitis; A, adenitis; BL, blepharitis; GS, gastroenteritis; CO, conjunctivitis; mo, months, y, years; d, days.
CONCOLINO ET AL. 2593
lesions manifes ted in the first year of the age but primarily involved
the cheeks, then spreading to extensor surface of the arms and
finally to the knees. The same onset was also reported in the
Moroccan PN patients [Mostefai et al., 2008]. Thus, we posit out
that the first localization of the rash may be variable and does not
represent per se a criterion for establishing or exc luding PN
diagnosis. The histology on the skin was not diagnostic and was
not a distinctive feature compared with RTS.
Isolated persistent severe neutropenia is the hallmark of this
genodermatosis, appearing between the first weeks and 20 months
of age. In Patients 2 and 3 the neutropenia was diagnosed at 2 years
and 18 months, respectively, while in Patient 1 the first observation
of neutropenia was at age 6, being unav ailable previous measure-
ments. We followed up the evolution of neutropenia in all three
patients for 4 years, and we never found a significant variation in
neutrophils absolute number (5001,100 mm
3
) suggesting that
neutropenia is no t cyclic as reported by Wang et al. [2003]. The
leukopenia can explain the several pulmonary infections, otit is
media, and sinusitis while it is not clear why the infective episodes
became less frequent during the adolescence and adult age as
observed in our patients though the neutropenia is persistent in
the long-term follow-up. Besides neutropenia, myelodysplasia
could be another distinctive feature of PN, as pointed out in
previous reports [Pianigiani et al., 2001; Van Hove et al., 2005;
Mostefai et al., 2008]. The detection of C16orf57 mutations in the
patient described by Pianigiani et al. [2001] is consistent with the
opinion that a few patients previously reported as RTS [Rizzari and
Conter, 1996] who also show myelodysplasia probably belong to
this syndromic entity.
Increase of enzymes as LDH and CPK has been reported by Van
Hove et al. [2005] and a possible muscle involvement has been
suggested. Our three sibs all had a slightly and episodic increase of
CPK (250380 U/L), while LDH was significantly increased with
values between 500 and 1,200 U/L. However, the electromyography
and muscular biopsy did not show any abnormality either in our
patients or in the patient described by Van Hove, preventing to
ascertain the origin of these enzymatic increases. The increased CPK
and LDH serum levels, in the absence of clinical evidence, appear to
be distinctive biochemical markers of PN, as they have never been
reported in RTS patients.
Growth delay is reported in some PN patients and it is probably
due to recurrent infectious diseases common in this syndrome.
Short stature, in our patients appeared in the first years of life, with
a deceleration of growth velocity after the age of 3 years, but no
sib had GH deficiency based on provocative GH test, or other
apparent causes of short stature.
Moreover, dysmorphic features such as hypoplasia of eyebrows,
frontal bossing, widely spaced eyes, midface hypoplasia, small nose,
depressed nasal bridge, and prognatism are common signs in our
siblings. Though an examination has not been made in all previ-
ously reported cases, the high similarity of craniofacial dysmor-
phisms between our male patient (Fig. 2) and the male patient
described by Van Hove et al. [2005], in particular, midface hypo-
plasia is recognizable by photographs. Moreover, moderate facial
dysmorphisms like ‘‘saddle nose’’ and hypertelorism are also
reported in the other Italian compound heterozygote for C16orf57
mutations [Pianigiani et al., 2001; Volp i et al., 2010]. Our clinical
report points to the wide phenotypic heterogeneity of PN syndrome
which deserves other observations to be further defined. Careful
bone marrow smears examination and follow-up for the hemato-
logic disease are needed to check the onset of myelodysplasia or
leukemic transformation.
Genome-wide SNPs array-based homozygosity mapping and
targeted next generation sequencing have proven to be the best
strategy to appoint C16orf57 as Clericuzio-type poikiloderma with
neutropenia gene, allowing to provide a complete genetic counsel-
ing from carrier testing through at-risk relatives, and hence to
plan out a targeted onco-hematologic surveillance for the affected
patients.
ACKNOWLEDGMENTS
This work was supporte d by the Nando Peretti Foundation (grant
2007/14) and by Associazione Italiana per la Ricerca sul Cancro
(AIRC) (grant 20082009/4217 to L.L.).
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2594 AMERICAN JOURNAL OF MEDICAL GENETICS PART A
    • "PN also features chronic neutropenia and bone marrow abnormalities, leading to infections mainly of the respiratory system and eventually to myelodysplasia associated with the risk of leukemic transformation (Arnold et al., 2010; Chantorn and Shwayder, 2012; Clericuzio et al., 2011; Clericuzio et al., 1991; Colombo et al., 2012; Concolino et al., 2010; Piard et al., 2012; Tanaka et al., 2010; Volpi et al., 2010; Walne et al., 2010). To date, 38 PN patients have been reported in the literature, and they bear 19 different mutations in the gene C16orf57 (Arnold et al., 2010; Chantorn and Shwayder, 2012; Clericuzio et al., 2011; Colombo et al., 2012; Concolino et al., 2010; Piard et al., 2012; Tanaka et al., 2010; Volpi et al., 2010; Walne et al., 2010), which encodes a 247 amino acid protein herein referred to as hMpn1 (for mutated in PN protein 1). Several PN patients have been misdiagnosed with dyskeratosis congenita (DC) or Rothmund- Thomson syndrome (RTS) because of a large overlap of the clinical manifestations of these syndromes (Colombo et al., 2012; Walne et al., 2010). "
    [Show abstract] [Hide abstract] ABSTRACT: Clericuzio-type poikiloderma with neutropenia (PN) is a rare genodermatosis associated with mutations in the C16orf57 gene, which codes for the uncharacterized protein hMpn1. We show here that, in both fission yeasts and humans, Mpn1 processes the spliceosomal U6 small nuclear RNA (snRNA) posttranscriptionally. In Mpn1-deficient cells, U6 molecules carry 3' end polyuridine tails that are longer than those in normal cells and lack a terminal 2',3' cyclic phosphate group. In mpn1Δ yeast cells, U6 snRNA and U4/U6 di-small nuclear RNA protein complex levels are diminished, leading to precursor messenger RNA splicing defects, which are reverted by expression of either yeast or human Mpn1 and by overexpression of U6. Recombinant hMpn1 is a 3'-to-5' RNA exonuclease that removes uridines from U6 3' ends, generating terminal 2',3' cyclic phosphates in vitro. Finally, U6 degradation rates increase in mpn1Δ yeasts and in lymphoblasts established from individuals affected by PN. Our data indicate that Mpn1 promotes U6 stability through 3' end posttranscriptional processing and implicate altered U6 metabolism as a potential mechanism for PN pathogenesis.
    Full-text · Article · Sep 2012
    • "Indeed, apart from our patients #17a and the infant #25, all herein described PN patients display overt skeletal signs including zygodactyly between the second and third digit (#26), multiple bone fractures (#11), intermediate osteopetrosis (#21) or X-ray detectable skeletal findings (#16) (Table 1). A relationship may be envisaged between zygodactyly and the swan neck hand hyperflexibility noticed in a few described patients [3,5,33]. More generally delayed bone maturation has been recorded [32] in the girl subsequently confirmed to carry two distinct C16orf57 mutations [6], and diffuse osteosclerosis has been underlined by Porter [26] in the patient found to harbour C16orf57 mutations [10]. "
    [Show abstract] [Hide abstract] ABSTRACT: Poikiloderma with Neutropenia (PN) is a rare autosomal recessive genodermatosis caused by C16orf57 mutations. To date 17 mutations have been identified in 31 PN patients. We characterize six PN patients expanding the clinical phenotype of the syndrome and the mutational repertoire of the gene. We detect the two novel C16orf57 mutations, c.232C>T and c.265+2T>G, as well as the already reported c.179delC, c.531delA and c.693+1G>T mutations. cDNA analysis evidences the presence of aberrant transcripts, and bioinformatic prediction of C16orf57 protein structure gauges the mutations effects on the folded protein chain. Computational analysis of the C16orf57 protein shows two conserved H-X-S/T-X tetrapeptide motifs marking the active site of a two-fold pseudosymmetric structure recalling the 2H phosphoesterase superfamily. Based on this model C16orf57 is likely a 2H-active site enzyme functioning in RNA processing, as a presumptive RNA ligase. According to bioinformatic prediction, all known C16orf57 mutations, including the novel mutations herein described, impair the protein structure by either removing one or both tetrapeptide motifs or by destroying the symmetry of the native folding.Finally, we analyse the geographical distribution of the recurrent mutations that depicts clusters featuring a founder effect. In cohorts of patients clinically affected by genodermatoses with overlapping symptoms, the molecular screening of C16orf57 gene seems the proper way to address the correct diagnosis of PN, enabling the syndrome-specific oncosurveillance. The bioinformatic prediction of the C16orf57 protein structure denotes a very basic enzymatic function consistent with a housekeeping function. Detection of aberrant transcripts, also in cells from PN patients carrying early truncated mutations, suggests they might be translatable. Tissue-specific sensitivity to the lack of functionally correct protein accounts for the main cutaneous and haematological clinical signs of PN patients.
    Full-text · Article · Jan 2012
  • [Show abstract] [Hide abstract] ABSTRACT: In this paper, the design and experimental testing of a direct-sequence spread spectrum (DSSS) system for wireless indoor infrared network is presented. This method improves the wireless IR communications performances against multipath propagation and narrowband interference. We have implemented an IR-DSSS prototype with 100 MHz code frequency and about 6 Mbps bit rate. We also present some results on a simplified synchronization structure so as to be used on reduced-cost domestic equipment. These systems are suitable for different applications at low and medium rates, especially for in-house communications between domestic appliances.
    Conference Paper · Feb 2004 · Orphanet Journal of Rare Diseases
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