18p - syndrome with a single central maxillary incisor

Solitary Median Maxillary Central Incisor Syndrome: A Case Report of a Unique Dental Anomaly

Solitary median maxillary central incisor (SMMCI) syndrome is complex and usually develops 35-38 days postconception during the intrauterine period. A noteworthy discovery is that just one central incisor in the maxillary alveolus, found exactly on the centerline, is present in both deciduous and permanent dentitions with other congenital anomalies. Around one in every 50,000 live babies exhibits this abnormality. This report describes the case of a 13-year-old female patient with SMMCI syndrome with a complaint about an unsightly appearance due to a single large upper front tooth. We underline the importance of increasing clinician awareness of SMMCI syndrome and the need for a multidisciplinary approach to its care.

Solitary Median Maxillary Central Incisor Syndrome: A Case Report

Aim

This report intends to present a case of solitary median maxillary central incisor syndrome (SMMCI) and its multidisciplinary team approach for diagnosis of other associated anomalies, with special emphasis on their management.

Background

Solitary median maxillary central incisor syndrome is a unique developmental condition characterized by only maxillary central incisor and a series of developmental defects, appearing as a syndrome. The appearance of a single incisor may take place due to the union of two incisor teeth or the absence of tooth germs. The mechanism of the fusion is still uncertain.

Case description

A 9-year-old female child reported with a chief complaint of pain in the right lower back tooth for the past 10 days. The presence of a single maxillary central incisor was an incidental finding. Then a detailed history and multidisciplinary evaluations revealed the diagnosis of SMMCI syndrome.

Conclusion

The effort in diagnosing and managing this syndrome had a strong impact on the child's life of which the parent was highly motivated and got a better understanding of associated problems of overall development.

Clinical significance

In SMMCI syndrome, the patient requires a multidisciplinary health team in order to improve their quality of life. It is of greater importance to diagnose the syndrome and treatment of these median line deformities.

How to cite this article

Balasubramanian S, Haridoss S, Swaminathan K. Solitary Median Maxillary Central Incisor Syndrome: A Case Report. Int J Clin Pediatr Dent 2022;15(4):458-461.

Solitary Median Maxillary Central Incisor Syndrome: An Exploration of the Pathogenic Mechanism

This study aimed to identify the genetic cause of one Chinese family with solitary median maxillary central incisor (SMMCI) and explore the relationship between genotype and its phenotype. One Chinese family with clinical diagnosis of SMMCI was collected. Single Nucleotide Polymorphism (SNP) array was performed and identified variation was confirmed by whole-genome sequencing (WGS). The reported chromosomal abnormalities and pathogenic genes in patients with SMMCI in literature were reviewed and summarized. The proband was an 8-year-old boy presenting a typical solitary median maxillary central incisor with a range of other phenotypic anomalies, including ptosis. SNP array revealed a 14.3 Mbp heterozygous deletion at chromosome 18p11.32-p11.21 in the proband but not in the unaffected parents. WGS further confirmed the identified deletion. 194 genes were involved in the chromosome region. Among them, 12 genes had been shown to be associated with diseases, including TGIF1, a reported SMMCI gene. The de novo 18p deletion resulted in SMMCI in the present study. Our results provide new genetic evidence that structural abnormality in chromosome 18p contributes to solitary median maxillary central incisor.

Orthodontic space closure in a young female patient with solitary median maxillary central incisor syndrome

A solitary median maxillary incisor can occur as a rare single dental anomaly or a symptom of the early-intrauterine developmental brain disorder of holoprosencephaly. The few published case reports about orthodontic treatment for this disorder have only described space opening for prosthodontic replacement of a central incisor. In contrast, the present patient was treated with extraction of the solitary median maxillary central incisor and orthodontic space closure with subsequent minimally invasive restorations in order to avoid looming esthetic or periodontal sequelae associated with any type of fixed bridgework or implant-borne crowns in the sensitive maxillary anterior area-which is especially indicated in young girls with a hyperdivergent growth pattern.

Solitary median maxillary central incisor syndrome: A rare entity

Solitary median maxillary central incisor (SMMCI) syndrome is a complex disorder and a rare dental anomaly, which is estimated to occur in approximately 1:50,000 live births. It is a unique developmental abnormality which involves the central incisor tooth germs, occurring with or without systemic involvement; hence, its early diagnosis is of great importance. The objective of this study was to discuss a case of SMMCI syndrome and various dental treatment alternatives available in management of such cases. Due to the possible association of this syndrome with other developmental problems, an early diagnosis and management becomes important. Moreover, when it is associated with other developmental malformation and defects, the management becomes multidisciplinary.

The solitary median maxillary central incisor (SMMCI) syndrome: Associations, prenatal diagnosis, and outcomes

Solitary median maxillary central incisor (SMMCI) syndrome is a complex disorder consisting of multiple, developmental defects involving midline structures of the head, which includes the cranial bones, the maxilla, and its container dentition (specifically the central incisor tooth germ), together with other midline structures of the body. SMMCI may appear as an isolated trait or in association with other midline developmental anomalies. We describe the case of a patient with SMMCI. He presented with a solitary median maxillary incisor, short stature, corpus callosum anomalies and a microform of holoprosencephaly (HPE), diabetes insipidus, and neurodevelopmental delay. The diagnosis was performed postnatally based on clinical features, radiological imaging, and a comprehensive genetic study. SMMCI can be diagnosed during the prenatal or neonatal periods or during infancy. Evaluation of the superior maxillary bone is important for prenatal diagnosis. Direct evaluation through bidimensional ultrasound or the use of multiplanar ultrasound or tridimensional reconstruction should be performed in cases of brain or face malformations. Early diagnosis can contribute to improved prenatal assessment and postnatal management.

Genotypic and phenotypic variation in six patients with solitary median maxillary central incisor syndrome

Solitary Median Maxillary Central Incisor occurs in 1 of 50,000 live births. It is the mildest manifestation of the holoprosencephaly spectrum and is genetically heterogeneous. Here we report six patients with solitary median maxillary central incisor, and a range of other phenotypic anomalies with different degrees of severity, varying from mild signs of holoprosencephaly to associated intellectual disability, and with different genetic background. Using array comparative genomic hybridization, pathogenic copy number variants were found in three of the six patients. Two patients had a deletion at the 18p11 chromosomal region that includes TGIF1 while the other patient had a deletion at 7q36, including the SHH gene. In one patient, a mutation in SIX3 was detected with exome sequencing, while in the two remaining patients all known holoprosencephaly genes were excluded using multiplex ligation-dependent probe amplification and sequencing, and remain unsolved. One of the two latter patients had isolated solitary median maxillary central incisor without other visible dentofacial anomalies, while the other had clinical features not part of the known holoprosencephaly spectrum.

Síndrome do incisivo central superior solitário: relato de caso

INTRODUÇÃO: a presença de um incisivo central superior solitário é um evento bastante incomum na população. A prevalência da chamada Síndrome do Incisivo Central Superior Solitário (SICSS) é verificada em 1:50.000 nascimentos, sendo registrado um maior acometimento no sexo feminino. Essa alteração no desenvolvimento da oclusão dentária é caracterizada por más formações estruturais, sobretudo na região de linha média do paciente. O diagnóstico precoce e o tratamento adequado dessa síndrome são de grande importância, pois essa condição talvez seja um indicativo de que o paciente pode apresentar outras más formações congênitas severas, não devendo ser a SICSS considerada uma simples anomalia dentária. Os procedimentos ortodônticos, nesses casos, variam dependendo do grau de comprometimento das estruturas ósseas da maxila, da oclusão em si, e principalmente da sutura palatina mediana. OBJETIVO: discutir, baseado em evidências científicas, aspectos importantes relacionados à SICSS, bem como apresentar um caso clínico de paciente do sexo feminino com SICSS, que foi submetida a tratamento ortodôntico na Clínica Odontológica Integrada Infantil da Universidade Federal de Santa Maria / RS. CONCLUSÃO: pela análise crítica da literatura, verifica-se ser muito importante o diagnóstico correto e precoce acerca dessa síndrome, visto que há possibilidade da mesma estar associada a outros problemas de desenvolvimento. Além disso, o paciente acometido pela SICSS deve ser assistido por uma equipe multidisciplinar de saúde, de forma a otimizar os resultados clínicos e devolver-lhe qualidade de vida.

A child with 18p- syndrome: a case report

18p- syndrome is caused by the deletion of all or a portion of genetic material on the short (p) arm of chromosome 18. It was first described in 1963 and since then there have been a variety of clinical characteristics associated with this syndrome. The patient described presented with learning difficulties, epilepsy, a characteristic round face and anti-mongoloid slant to the eyes. Orally he had a single maxillary central incisor and a high caries rate which necessitated comprehensive dental treatment under general anesthesia.

Contiguous gene syndrome of holoprosencephaly and hypotrichosis simplex: association with an 18p11.3 deletion

We report a patient with a unique combination of features, including microcephaly; mental retardation; poorly developed frontal lobes; hypoplastic pituitary gland; hypothyroidism; alopecia universalis; single maxillary central incisor; taurodontism; median palatal ridge; longitudinally grooved nails; and scoliosis. His unbalanced karyotype was found to be 45,XY,der(15;18)(q10;q10). The constellation of anomalies appears to represent a contiguous gene syndrome caused, at least in part, by deletion of TGIF and the gene responsible for hereditary hypotrichosis simplex. The phenotype of our patient differs other reported patients with del(18p). Possible explanations include (1) the effects of a different deleted region, (2) a positional effect caused by a gene close by, or (3) by interruption of a different gene resulting from chromosomal translocation.

Solitary median maxillary central incisor (SMMCI) syndrome

Solitary median maxillary central incisor syndrome (SMMCI) is a complex disorder consisting of multiple, mainly midline defects of development resulting from unknown factor(s) operating in utero about the 35th-38th day(s) from conception. It is estimated to occur in 1:50,000 live births. Aetiology is uncertain. Missense mutation in the SHH gene (I111F) at 7q36 may be associated with SMMCI. The SMMCI tooth differs from the normal central incisor, in that the crown form is symmetric; it develops and erupts precisely in the midline of the maxillary dental arch in both primary and permanent dentitions. Congenital nasal malformation (choanal atresia, midnasal stenosis or congenital pyriform aperture stenosis) is positively associated with SMMCI. The presence of an SMMCI tooth can predict associated anomalies and in particular the serious anomaly holoprosencephaly. Common congenital anomalies associated with SMMCI are: severe to mild intellectual disability, congenital heart disease, cleft lip and/or palate and less frequently, microcephaly, hypopituitarism, hypotelorism, convergent strabismus, oesophageal and duodenal atresia, cervical hemivertebrae, cervical dermoid, hypothyroidism, scoliosis, absent kidney, micropenis and ambiguous genitalia. Short stature is present in half the children. Diagnosis should be made by eight months of age, but can be made at birth and even prenatally at 18-22 weeks from the routine mid-trimester ultrasound scan. Management depends upon the individual anomalies present. Choanal stenosis requires emergency surgical treatment. Short stature may require growth hormone therapy. SMMCI tooth itself is mainly an aesthetic problem, which is ideally managed by combined orthodontic, prosthodontic and oral surgical treatment; alternatively, it can be left untreated.

Solitary median maxillary central incisor and normal stature: a report of three cases

Solitary median maxillary central incisor (SMMCI) is a rare finding. Growth deficiency or other systemic abnormalities may or may not be seen in children with this anomaly. Nevertheless, the growth and development of all children with SMMCI should be closely monitored. This article reports the dental findings of three Chinese girls with SMMCI, but no growth deficiency or other systemic involvement.

A patient with hypopituitarism and isochromosome 18q mosaicism

AIMS

Patients with isochromosome 18 [i(18q)] have features of both trisomy 18 and deletion of 18p [del(18p)] syndromes. Although, hypopituitarism has been reported in patients with del(18p) syndrome, it has not been described in patients with i(18q) syndrome previously. We describe a case with i(18q)/del(18p) mosaicism associated with a novel finding of hypopituitarism.

METHODS

Clinical characteristics of the patient have been discussed in the light of the literature.

RESULTS

The patient had dysmorphic findings that are predominantly seen in del(18p) syndrome such as low nasal bridge, wide mouth, large ears, high forehead, hypopigmentation, upturned nostrils and hypopituitarism (TSH, ACTH, and GH deficiencies, and pituitary hypoplasia on magnetic resonance imaging). In addition, she also had upturning of upper lip and seizures, which are features of trisomy 18 syndrome.

CONCLUSIONS

In agreement with the previous clinical reports, this case further supports the presence of a factor, which is involved in pituitary development and/or function, on the short arm of chromosome 18.

Velocardiofacial syndrome with single central incisor

Three siblings and their mother are reported who all had cytogenetically proven velocardiofacial syndrome (VCFS). One boy had normal dental and craniofacial findings, except for an increased cranial base angle. His sister had only one central incisor in the maxilla. One central incisor had also been missing in the primary dentition. She had no labial frenulum present. Cephalometry showed a small maxillary unit length indicating mild maxillary hypoplasia, an increased anterior face height, steep mandibular plane angle, retruded chin, and a large cranial base angle. Dental measurements showed retroclined lower incisors and increased interincisal angle. A second sister had a cleft of the secondary palate. All permanent teeth were present with the exception of a missing central incisor in the lower jaw: the single lower central incisor was situated in the midline. Her cephalometry showed similar findings as in her sister. All three siblings required palate surgery for speech. Mother was not available for detailed dental and other oral investigations. A single maxillary central incisor has previously been reported in VCFS, but to our knowledge a single central incisor in the mandible has not been reported previously in this entity.

SHH mutation is associated with solitary median maxillary central incisor: a study of 13 patients and review of the literature

Solitary median maxillary central incisor (SMMCI) or single central incisor is a rare dental anomaly. It has been reported in holoprosencephaly (HPE) cases with severe facial anomalies or as a microform in autosomal dominant HPE (ADHPE). In our review of the literature, we note that SMMCI may also occur as an isolated finding or in association with other systemic abnormalities. These anomalies include short stature, pituitary insufficiency, microcephaly, choanal atresia, midnasal stenosis, and congenital nasal pyriform aperture stenosis. SMMCI can also be a feature of recognized syndromes or associations or a finding in patients with specific chromosomal abnormalities. We performed a molecular study on a cohort of 13 SMMCI patients who did not have HPE. We studied two genes, Sonic Hedgehog (SHH) and SIX3, in which mutations have been reported in patients showing SMMCI as part of the HPE spectrum. A new missense mutation in SHH (I111F), segregating in one SMMCI family, was identified. Our results suggest that this mutation may be specific for the SMMCI phenotype since it has not been found in the HPE population or in normal controls. Published 2001 Wiley-Liss, Inc.

Heterotaxy with left atrial isomerism in a patient with deletion 18p

We report on a female infant with partial deletion of the short arm of chromosome 18 (del 18p) and heterotaxy with left atrial isomerism. Congenital heart defect (CHD) is found in 10% of the literature reports. Interestingly, situs abnormalities have been diagnosed in four patients with del 18p, including ours. This finding could imply that a locus or loci involved in the development of normal body situs lies within this chromosomal region. Del 18p must be consid- ered when evaluating a patient with phenotypic anomalies and CHD in lateralization defects.

A solitary maxillary central incisor treated orthodontically: a case report

The presentation of a solitary maxillary central incisor is reported and its association with other congenital abnormalities discussed. It is an important finding for dental health professionals, since it may indicate the presence of other significant midline congenital abnormalities. It may also indicate the presence of associated disorders that profoundly affect growth and development and which, once identified, may be treated.

Solitary maxillary central incisor in the midline associated with systemic disorders

A single maxillary central incisor in the midline is a rare developmental anomaly. The appearance of a single incisor in place of two teeth may occur as an isolated dental finding that can be related to fusion of two neighboring teeth or to agenesis of a tooth germ. However, the condition has also been reported to occur in association with autosomal dominant holoprosencephaly, growth retardation, and midline developmental defects. This article reports on other systemic defects that can be found in association with a single maxillary central incisor.

Solitary median maxillary central incisor, short stature, choanal atresia/midnasal stenosis (SMMCI) syndrome

This article describes a series of 21 consecutive cases, each involving a solitary median maxillary central incisor; the patients were seen in the Department of Dentistry or the Victorian Clinical Genetics Unit, Murdoch Institute, at the Royal Children's Hospital, Melbourne, from 1966 to 1997. The spectrum of anomalies and associated features present in these cases--solitary median maxillary central incisor, choanal atresia, and holoprosencephaly--is described, and the literature related to the features, including genetic studies in these conditions, is reviewed. We relate our findings in these cases to current knowledge of developmental embryology. It is hoped that the findings, together with our interpretation of them, will help to clarify understanding of solitary median maxillary central incisor syndrome. This syndrome was previously considered a simple midline defect of the dental lamina, but it is now recognized as a possible predictor of holoprosencephalies of varying degrees in the proband, in members of the proband's family, and in the family's descendants.

Single mandibular incisor in a patient with del (18p) anomaly

A single mandibular incisor and an unusually narrow mandible and tongue were noted in an 8-year-old moderately retarded boy with 18p- (45, XY, der dic (18) (18qter-p11.2::22p 11.2-qter). While a single maxillary incisor, considered a minor feature of holoprosencephaly, was reported in three cases of 18p-, reduction of mandibular incisors has been a very rare finding and has never been noted in similar cases.

A retrospective CISS hybridization analysis of a case with de novo translocation t(18;22) resulting in an 18p- syndrome

An unbalanced de novo translocation t(18;22) leading to a severely malformed liveborn girl with 18p- syndrome is described. Using the chromosomal in situ suppression (CISS) hybridization technique on 4-year-old G-banded chromosome preparations, it could be demonstrated that the translocation chromosome is composed of the long arm including the centromere of a chromosome 22 and the long arm of a chromosome 18. Consequently, the patient described here has lost the short arm including the centromere of chromosome 18. The possibility of restudying cytogenetically unsolved cases in clinical cytogenetics using older G-banded chromosome preparations with the fluorescence in situ hybridization techniques is pointed out.

Single maxillary central incisor in a girl with del(18p) syndrome

We present a girl with del(18p) syndrome and a single maxillary central incisor; she is only the second patient in whom this association has been reported.

Two unrelated cases of single maxillary central incisor with 7q terminal deletion

Two unrelated cases of single maxillary central incisor (SM-CI) with 7q terminal deletion of the same breakpoint at 7q36.1 were described. They had mental retardation, microcephaly, hypotelorism, short stature, and normal levels of plasma growth hormone. One case had bilateral caudal ectopic kidneys, double renal pelves, and dilated ureters. The other had bilateral hydroureteronephrosis. The present cases suggest that 7q terminal deletion is one of the causes of SMCI.

Perspectives on holoprosencephaly: Part III. Spectra, distinctions, continuities, and discontinuities

This paper attempts to balance our knowledge of holoprosencephalic spectra and continuities with important distinctions and discontinuities. Prevalence studies and syndrome delineation are briefly reviewed. The following topics receive detailed coverage: human teratogens, special aspects of forebrain and hindbrain malformations, aprosencephaly/atelencephaly, association with neural tube defects, current assessment of "facial principles," and endocrine abnormalities.

18p- syndrome with partial sacral agenesis

Images

Single maxillary central incisor and coloboma in hypomelanosis of Ito

Incontinentia Pigmenti Achromians is a neurocutaneous disorder of uncertain etiology that has been associated with other systemic manifestations including ophthalmologic, musculoskeletal, neurologic and dental abnormalities. Chromosome abnormalities have been documented in some cases but may be coincidental. We describe a 16-month-old black female with an iris coloboma and single central deciduous maxillary incisor in addition to the hypopigmented skin lesions of hypomelanosis of Ito. The combination has not been previously described.

Segregation patterns and phenotypes of unbalanced offspring in a large family with (10;18) chromosome translocation

We describe a large family in whom a balanced 10;18 chromosome translocation is segregating through five generations. Six severely mentally retarded relatives and an abnormal fetus further define the phenotypic expression of dup (18q21----qter). Other segregants detected prenatally included a fetus with deletion 18q21----qter and two fetuses with dup(18pter----q21) owing to tertiary trisomy. One of the latter also had an extra X chromosome; this might be another example of possible nonhomologous pairing in man.