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Keywords:

  • mandibulo-facial dysostosis;
  • microcephaly;
  • developmental delay;
  • microtia;
  • choanal atresia

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. DISCUSSION
  6. Acknowledgements
  7. REFERENCES

Treacher Collins syndrome (TCS, OMIM 154500) is a well-defined mandibulofacial dysostosis characterized by symmetric facial anomalies consisting of malar hypoplasia, coloboma of the lower eyelid, dysplastic ears, micrognathia, cleft palate and deafness. Other mandibulofacial dysostoses (MDs) such as Toriello (OMIM 301950), Bauru (OMIM 604830), Hedera–Toriello–Petty (OMIM 608257), and Guion-Almeida (OMIM 610536) syndromes are less well characterized and much rarer. Here we describe three unrelated patients showing clinical features overlapping with TCS, but who in addition have developmental delay, microcephaly and a distinct facial gestalt. Because of the distinct ear anomalies and the hearing loss a HOXA2 mutation was taken into account. CHARGE syndrome was discussed because of ear anomalies, choanal atresia, and developmental delay in our patients. But mutational analyses including sequencing of the TCOF1, the HOXA2, and the CHD7 genes, deletion screening of the TCOF1 gene as well as genomewide array analyses revealed normal results. We suggest that these three patients have a new type of mandibulofacial dysostosis. As all three cases are sporadic and both sexes are affected the pattern of inheritance might be autosomal dominant or autosomal recessive. Identification of additional patients will allow to further delineate the phenotype, to assign the inheritance pattern and to identify the molecular basis. © 2009 Wiley-Liss, Inc.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. DISCUSSION
  6. Acknowledgements
  7. REFERENCES

Several mandibulofacial dysostoses (MDs) with distinct associated anomalies and different inheritance patterns have been described. As of now, the Treacher Collins syndrome (OMIM 154500), which is the most frequent and best known MD, is the only MD that has been associated with single gene alterations, namely heterozygous mutations of the TCOF1 gene [Treacher Collins Collaborative Group, 1996]. All other MDs are rarer—each with less than eight patients described in the literature—and, therefore the latter are less well characterized and their specific genetic etiology is still unknown. These MDs include autosomal dominant types, such as Hedera–Toriello–Petty (OMIM 608257) [Hedera et al., 2002], Bauru (OMIM 604830) [Marcano and Richieri-Costa, 1998], and Guion-Almeida (OMIM 610536) [Guion-Almeida et al., 2006] as well as the X-linked type Toriello (OMIM 301950) [Toriello et al., 1985].

Mutations in the HOX2A gene were described to be responsible for microtia, deafness and cleft palate by Alasti et al. 2008 and the combination of ear anomalies, deafness, choanal atresia, and developmental delay is characteristic in patients with CHARGE syndrome [Vissers et al., 2004].

Here we describe three unrelated patients with microcephaly, microtia with preauricular and buccal tags, choanal atresia and global developmental delay. We did not find any mutation in the TCOF1 (5q33.1), CHD7 (8q12.2), and HOXA2 (7p15.2) genes and no chromosomal aberrations were identified. The clinical phenotype was different from TCS, the other MD's, OAVS (OMIM 164210), and oto-facial syndrome (OMIM 221300). Therefore, we hypothesize that the three patients reported here represent a new, previously unreported MD.

CLINICAL REPORTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. DISCUSSION
  6. Acknowledgements
  7. REFERENCES

Patient 1

Patient 1, a girl, was born to a healthy nonconsanguineous Turkish couple after premature amniorrhexis at 34 gestational weeks with normal measurements for weight [1,500 g (−1.8 SD)] and length [45 cm (−0.2 SD)], but with microcephaly [OFC: 27 cm (−2.8 SD)]. She had bilateral microtia with hypoplasia especially of the upper part of the helix and a narrow auditory canal, left-sided preauricular tag, bilateral choanal atresia and a mild pulmonary stenosis (Fig. 1A–C). Her facial features comprise malar hypoplasia, micrognathia and downslanting palpebral fissures. A conductive hearing loss was diagnosed.

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Figure 1. Facial phenotype of patient 1 (AC) in the newborn period and (DF) at the age of 3 months. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.].

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At re-examination at the age of equation image months (corrected to 2 months due to preterm birth) she still was microcephalic [OFC: 32 cm (−2.8 SD)] and short stature [length: 49 cm (−2.5 SD)] became apparent. She still needed a tube for respiration because of narrow upper airways. She showed craniofacial dysmorphism with microcephaly, flat malar regions, upturned nose possibly due to the implanted stents, micrognathia, and bilateral microtia (Fig. 1D–F). Her psychomotor development was delayed.

Chromosomal analysis from lymphocytes revealed a normal female karyotype (46,XX) at a banding resolution of ∼400 bands per haploid genome. Sequencing of the CHD7, HOXA2, and TCOF1 genes was normal. TCOF1 variants detected in this patient are not listed in dbSNP (BUILD 129) and not located within putative transcription factor binding sites.

Patient 2

Patient 2, a boy, was born after an uneventful pregnancy to a 35-year-old mother and a 37-year-old father of German origin. Both parents are healthy and they are nonconsanguineous. Birth occurred at 42 weeks of gestation with a normal length [52 cm (−1.2 SD)] but with dystrophy [3,180 g (−3.1 SD)] and microcephaly [33 cm (−2.2 SD)]. The newborn period was complicated due to bilateral choanal atresia requiring stents until the age of 4 months. He also had a median cleft palate, hypertelorism, upward slanting palpebral fissures, short nose with anteverted nares, a thin upper lip, bilateral microtia with atresia of external auditory canal, and a preauricular and a buccal tag on the left side (Fig. 2A–C). A CT scan of the petrosal bone showed normal inner ear structures and a normal internal auditory canal on both sides. To correct conductive hearing loss he received bone conduction hearing aids. An atrial septal defect type II was diagnosed. An MRI scan of the brain at the age of 12 months revealed a delayed myelinisation. A radiograph of the left hand taken at the age of 15 months showed that his bone age was retarded by 3 months.

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Figure 2. Facial phenotype of patient 2 (AC) at the age of 3 months, (D) at the age of 10 months, (E) at the age of 3 years, (F) at the age of 7 years. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.].

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At re-examination at the age of equation image years, he had normal height [100 cm (mean)] and weight [15 kg (mean)] but he was still microcephalic [45 cm (−4.0 SD)]. His psychomotor development was delayed: Sitting at 8 months, walking without support at 16 months, first words at 21 months. He presented with upslanting palpebral fissures, hypertelorism, anteverted nares, small teeth, bilateral microtia with hypoplasia especially of the upper part of the helix (Fig. 2D–F) and hypoplastic toenails.

At age 8 years, he now attends a school for the physically handicapped and has mild mental retardation. Generalized seizures became apparent at the age of 7 years.

Chromosomal analysis from lymphocytes revealed a normal male karyotype (46,XY) at a banding resolution of 410 bands per haploid genome. Mutational analysis of the TCOF1, the CHD7, and the HOXA2 genes showed no apparent pathogenic mutation. Fluorescent in situ hybridization (FISH) analysis with BAC-probes CTD-2514E15 and RP11-802B10, both spanning the whole TCOF1 gene, gave normal results and MLPA of the CHD7 gene did not reveal a deletion. A SNP array analysis (GeneChip® Human Mapping 250 K SNP array (StyI), Affymetrix, Santa Clara) showed no pathogenic aberration.

Patient 3

Patient 3, a girl, is the first child of a nonconsanguineous Spanish couple. The father has a very mild malar hypoplasia, but no further facial dysmorphism or anomaly is present.

Early in pregnancy an increased nuchal translucency was detected. On amniocentesis a normal karyotype was observed (46,XX). Microcephaly was evident on ultrasound examination at 30 weeks of gestation. Birth occurred at 39 weeks of gestation, APGAR scores were 9 and 10 at 1 and 5 min, respectively. She presented with microcephaly [OFC: 30 cm (−3.7 SD)] and bilateral microtia (Fig. 1A–B), weight and length were in the lower normal range [weight: 2,850 g (−1.1 SD); length 46 cm (−1.8 SD)]. Because of swallowing problems a gastrostomy was performed at the age of 6 weeks and is continued until now. There is no apparent drooling. The girl has the tendency to sleep in a strange position; but sleep apneas have been excluded. Bilateral conductive hearing loss required bone-anchored hearing aids (BAHA).

Upon examination at the age of 3 years, she still showed severe microcephaly [OFC: 41 cm (−6.0 SD)] but normal measurements for weight [16.2 kg (1.3 SD)] and height [93.5 cm (−0.8 SD)]. Craniofacial features consisted of a sloping forehead, a very small anterior fontanelle, short and horizontal palpebral fissures, malar hypoplasia, prominent nasal bridge, microretrognathia, dysplastic and hypoplastic ears, stenosis of the right external auditory canal and two bilateral preauricular tags (removed on the right side) (Fig. 3C–G). She also has unilateral choanal atresia. Short neck, slender fingers with proximally located and mildly hypoplastic thumbs with unilateral decreased mobility at the interphalangeal joint were also noted (Fig. 3H). She presented with mild to moderate developmental delay with walking without support at the age of 2 years and speaking of first words at 20 months of age with a very poor expressive language development at the age of 3 years.

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Figure 3. Facial phenotype of patient 3 (A,B) in the newborn period with dyplastic ears, more severely on right side, (C,D) at 3 months of age, (E) at 24 months of age, (F) at equation image years, (G) at 5 years. H: Right hand of the patient with hypoplastic thumb. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.].

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Cerebral and abdominal ultrasound, echocardiography and brain MRI were normal. Cranial CT revealed hypoplastic middle ear ossicles and hypoplastic lateral semicircular canals. Radiographs of the skull, lateral thoracolumbar spine, upper and lower limb did not show any abnormalities besides microcephaly and slightly proximally placed thumbs.

Chromosomal analysis from blood lymphocytes revealed a normal karyotype (46,XX) and an 1 Mb BAC array extended with additional BACs in targeted regions [Cuscó et al., 2008] did not show any pathogenic change. Mutational analysis of the TCOF1, the HOXA2, and the CHD7 genes did not reveal any mutations.

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. DISCUSSION
  6. Acknowledgements
  7. REFERENCES

The three patients described here show a combination of microcephaly, microtia, preauricular tags, choanal atresia, and developmental delay. In all three, the initial tentative diagnosis was Treacher Collins syndrome (TCS, Franceschetti–Klein syndrome, OMIM 154500). However, molecular testing including point mutation and deletion analysis of the TCOF1 gene [Treacher Collins Collaborative Group, 1996] showed normal results. All clinical findings of the three patients have been described in patients with TCS. However, microcephaly and global developmental delay are uncommon in patients with TCS who show mutations in the TCOF1 gene (1/36 and 3/24 patients, respectively [own unpublished data and Teber et al., 2004]). In addition, the patients described here have distinctive ear malformations: the lower part of the ear is nearly normal, whereas the upper part is severely hypoplastic due to the absence of the triangular fossa and the superior (posterior) crus of the anthelix [Hunter and Yotsuyanagi, 2005]. In addition, the external auditory canal is stenotic or atretic. These findings result in a specific form of microtia. Preauricular and buccal tags, often associated with microtia, have also been reported in TCS, but especially buccal tags are uncommon in TCS (own unpublished data). Therefore, the pattern of clinical findings in our three patients is not compatible with that seen in patients with TCS. The negative results of TCOF1 mutation analysis also indicate that these children do not have TCS, although the mutation detection rate varies between 60% and 93% (60% [Edwards et al., 1997], −77% [Teber et al., 2004], −93% [Splendore et al., 2000]).

In the literature a few chromosomal aberrations that can result in MD have been described. Stevenson et al. 2007 reported a de novo translocation [t(2;17)] that disrupts the HOXD cluster and results in a phenotype with mandibulofacial dysostosis. An interstitial deletion [del(3)(p23p24.12)] was reported in a patient with mild mandibulofacial dysostosis [Arn et al., 1993]. Patients with clinical diagnosis of TCS have been shown to carry a deletion [del(4)(p15.32p14)] [Jabs et al., 1991] or a translocation [t(6;16)(p21.31;p13.11)] [Dixon et al., 1991]. The three patients reported here had a normal karyotype. In addition, 250 k SNP array analysis in patient 2 and BAC array CGH in patient 3 revealed a normal profile in both patients. Therefore it is unlikely that the clinical phenotype in our patients is caused by a chromosomal aberration.

Oculo-auriculo-vertebral spectrum (OAVS, OMIM164210) is another differential diagnosis (Table I) which has to be discussed in our patients because of microtia, isolated or combined with other anomalies, is accepted to be the minimal manifestation of this disease [Rollnick et al., 1987]. Therefore, formally one could diagnose bilateral OAVS in our three patients. However, none of the three patients has any facial asymmetry or any other major clinical features of OAVS, for example, dermoids and vertebral defects. Moreover, some consistent findings in our three patients, namely choanal stenosis/atresia, microcephaly (8%) and global developmental delay (9%), are uncommon in OAVS [Tasse et al., 2005]. Therefore, this diagnosis is not appropriate for our patients.

Table I. Clinical Findings in These Patients Reported Here Compared to Differential Diagnoses
 Patient 1Patient 2Patient 3Treacher Collins syndromeaCHARGE syndromebHOXA2 related microtiacOto-facial syndromedWieczorek et al. 2007OAVSeMD Toriello typeMD Toriello–Hedera–Petty typeMD Bauru typeMD Guion-Almeida type
  • +, present; −, absent; n.r., not reported.

  • a

    Teber et al. 2004.

  • b

    Sanlaville and Verloes 2007.

  • c

    Alasti et al. 2008.

  • d

    Mégarbané et al. 2005.

  • e

    Tasse et al. 2005.

Prenatal microcephaly+++(−)n.r.++(+)++
Postnatal microcephaly+++4%(−)n.r.++(+)++
Gobal developmental delay(+)++11%>70%n.r.++(+)(+)+
Craniofacial dysmorphism             
Palpebral fissuresDownslantingUpslantingUpslantingDownslantingHorizontaln.r.UpslantingUpslantingHorizontalDownslantingDownslantingUpslantingUpslanting
Lower eyelid coloboma50%n.r.n.r.
Malar hypoplasia+++100%n.r.n.r.+++++
Microtia+++78%95–100%++++++++
Atresia/stenosis of external auditory canalBilateralBilateralUnilateral27%+++++++++
Preauricular tagUnilateralUnilateralBilateral27%+n.r.+++
Buccal tagUnilateraln.r.+
Micrognathia+++89%+n.r.n.r.++++++
Cleft palate+33%15–20%++++++
Choanal atresiaBilateralBilateralUnilateral28%35–65%n.r.n.r.n.r.+
Conductive hearing loss+++88%60–90%++++++
Congenital heart defectPulmonic stenosisASDII4%50–85%n.r.n.r.++Pulmonic stenosis, mitral incompetenceASD

Patients with very similar anomalies of the ears and hypoplasia of the malar region have been described by Mégarbané et al. 2005 in oto-facial syndrome (OMIM221300) and by Wieczorek et al. 2007. In contrast to the three patients described here, those patients presented with esophageal atresia and short stature, whereas choanal atresia was missing. Thus, we clinically excluded these diagnoses, although patient 2 has a similar facial phenotype.

The combination of congenital heart defect, choanal stenosis/atresia, retardation of development and ear abnormalities brings up CHARGE (Coloboma, Heart defects, choanal Atresia, Retarded growth and development, Genital abnormalities, and Ear anomalies) syndrome (OMIM 214800) as a further differential diagnosis [Vissers et al., 2004]. In patients with CHARGE syndrome as well as in our patients the vertical ear height is reduced. However, the typical CHARGE ear is characterized by hypoplasia of the lower part of the ear, and in contrast to our patients, the ear is square, low-set, and protruding [Jongmans et al., 2006]. Other clinical features in our patients that are at variance with CHARGE syndrome are microcephaly and malar hypoplasia whereas coloboma of iris or retina, genital anomalies and retardation of growth, which are typical clinical findings of CHARGE syndrome, are lacking in our patients. In addition, mutational analysis of the CHD7 gene did not reveal a pathogenic mutation in patients 1 and 2. Thus, this makes this diagnosis unlikely.

Patients with HOXA2 mutations (OMIM 604685) present with external ear abnormalities—very similar to our patients—in association with hearing loss and cleft palate. Although our three patients showed additional clinical signs not present in the family described by Alasti et al. 2008 we decided to screen the HOXA2 gene for mutations. We could not identify a mutation and therefore concluded that our patients suffer from a condition distinct from the family described by Alasti et al. 2008.

Besides TCS, there are at least four other mandibulofacial dysostoses (MDs) listed in OMIM. They all are rare and their etiology is unknown to date. However, none of these MDs is a likely diagnosis in our patients: (1) Mandibulofacial dysostosis, Toriello type (OMIM 301950), is X-linked—therefore definitely different from our patients—and characterized by microcephaly, downslanting palpebral fissures, low-set protruding ears, bilateral hearing loss, short stature, cryptorchidism, and congenital heart defect. The face resembles a mild form of Treacher Collins syndrome [Toriello et al., 1985; Delb et al., 2001]. (2) Mandibulofacial dysostosis, Hedera–Toriello–Petty type (OMIM 608257), was described in a family with eight affected members with an autosomal dominant inheritance [Hedera et al., 2002]. Clearly different from our patients is the bilateral ptosis, which was absent in all our patients. (3) Mandibulofacial dysostosis, Bauru type (OMIM 604830), is inherited in an autosomal dominant manner and can be distinguished from the other mandibulofacial dysostoses by the presence of cleft lip with/without cleft palate [Marcano and Richieri-Costa, 1998]. (4) Mandibulofacial dysostosis, Guion-Almeida type (OMIM 610536), was reported in four Brazilian patients [Guion-Almeida et al., 2006], who have a similar facial phenotype and similar ears compared to our patients, but do not present with choanal atresia. In addition, they have short stature in contrast to our patients. At present time, one cannot exclude that all these MD's belong to a spectrum of one variable clinical condition.

In conclusion, our three patients appear to have a previously unrecognized mandibulofacial dysostosis of unknown etiology characterized by microcephaly, microtia, preauricular tags, choanal atresia and developmental delay, which is similar but distinct from TCS.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. DISCUSSION
  6. Acknowledgements
  7. REFERENCES

We thank the participating patients and their parents for taking part in this study, Ludger Klein-Hitpass and Ivon Cuscó for performing the array analyses, Corinne Collet for mutational screening of the TCOF1 gene in patient 3, Winfried Imm for providing us with clinical data, Peter Meinecke for helpful discussion and Bernhard Horsthemke for continuous support. This work was supported by grants of the Deutsche Forschungsgemeinschaft (DFG Wi1440/6-4) and the Bundesministerium für Bildung und Forschung, CRANIRARE (BMBF 01GM0802).

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. DISCUSSION
  6. Acknowledgements
  7. REFERENCES
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