You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
aglossia congenita ( ac ) , congenital absence of the tongue , is a rare and unusual midline developmental anomaly usually associated with craniofacial and limb defects and has overlapping features with other syndromes .
all these syndromes are now believed to belong to a family of oromandibular limb hypogenesis syndrome ( olhs ) .
the incidence of olhs is very low ( 1/175,000 live births ) and most cases are actually hypoglossia rather than true aglossia .
this is a rare case of isolated ac , unusual median palatal grooving , and remarkable functional adaptability in a young indian male patient .
a 28-year - old indian male reported with the chief complaint of missing lower anterior teeth and wanted prosthetic replacement for the same .
he gave a history of missing deciduous mandibular incisors and inability to speak until 5 years of age .
he was born from a non - consanguineous marriage , and his parents and three siblings were normal with no craniofacial and skeletal abnormalities .
the mother gave a history of intake of some medication during pregnancy in the first trimester .
he was of medium height with a long narrow face , pointy tapering chin , saddle nose , broad nasal alae , low set ears , fused eyebrows , thin lips , and microstomia .
there was no facial palsy , hearing defects or difficulty in swallowing solids and liquids .
intraoral examination revealed a smooth mucosa of the floor of the mouth and complete absence of tongue .
the oro - pharyngeal isthmus was constricted with absence of the palatoglossal arches [ figure 1 ] .
the permanent mandibular incisors ( 32,31,41,42 ) , maxillary lateral incisors ( 12,22 ) , second premolars ( 15,25,35,45 ) , and mandibular third molars ( 38,48 ) were missing .
the palate was also narrow and constricted with an unusual median groove [ figure 2 ] .
note mucosa of floor of mouth in place where the tongue is normally present , the constricted oropharyngeal isthmus , and hypertrophied uvula median groove in palate ; the palate appears constricted with median groove but no cleft interestingly , any attempt to perform functions related to the tongue would cause the mucosa of the floor of the mouth to balloon out mimicking the absent tongue [ figure 3 ] .
he had not undergone any specialist speech therapy but had taught himself to speak clearly with repeated practice and personal effort ( even lingual consonants ) .
ballooning of mucosa in floor of mouth on attempted tongue movements the radiographs did not show any impacted teeth or evidence of bony cleft in the palate .
there was inter - dental bone loss and radicular cyst in association with left mandibular first molar ( 36 ) [ figure 4 ] .
note missing teeth , poor periodontal bone support , radicular cyst in relation to 36 , decreased alveolar bone height , and absence of palatal bony defect lateral cephalogram of patient .
note the lingually inclined anterior mandibular alveolar bone with decreased height , prominent chin , and increased gonial angle multidisciplinary approach towards treatment was adopted .
teeth 18 , 17 , 16 , 24 , 34 , and 44 were endodontically treated .
the patient is undergoing transverse maxillary arch expansion at present to be followed by anterior mandibular transverse expansion and mandibular ridge augmentation with autologous rib graft .
the association of aglossia with anomalies of limbs was noted by kettner ( 1907 ) and the first report of aglossia  adactylia syndrome was reported by rosenthal ( 1932 ) .
aglossia / hypoglossia has been reported with numerous other developmental abnormalities and systemic manifestations , the most common being craniofacial and limb defects [ table 1].[18 ] manifestations reported in association with aglossia / hypoglossia[18 ] hall 's classification of olhs ( 1971 ) , dividing the spectrum of manifestations into five types , is widely accepted [ table 2 ] .
halls classification of oromandibular limb hypogenesis syndrome ac associated with microstomia , oligodontia , median palatal groove , and maxillo - mandibular hypoplasia without any limb defects was seen in this case . according to hall 's classification ,
this case would represent olhs type i b. embryologically , aglossia could be explained by the failure of development of the two lingual swellings and the tuberculum impar but the cause for this is not known .
several theories have been proposed like role of intrauterine factors and membranous strands produced by rupture of amnion in early pregnancy causing constriction or amputation of limbs and oral anomalies due to ingestion of these strands during oral development .
recently , heart and neural crest derivatives expressed protein 2 ( hand 2 ) , a transcription factor has been found to play a role in tongue morphogenesis and limb and branchial arch development in experimental animal studies and may be associated with olhs .
most of the cases are sporadic but a few intra - familial cases led to the hypothesis of mutation in an autosomal recessive gene .
maternal febrile illness , hypothyroidism , and cytomegalovirus infection have also been implicated as etiological factors .
teratogenic etiology due to ingestion of drugs and herbs ( perovskia abrotanoids ) by mother during gestation could play a role and should be avoided .
drugs ingested by the mother may be an etiological factor in this case although the type of drug could not be determined .
it is now believed to be caused by heat - induced vascular disruption around the fourth embryonic week .
chorionic villous sampling when performed before 10 weeks of amenorrhea has been associated with this disorder giving further support to the disruptive vascular hypothesis .
aglossia may be associated with a number of syndromes , some of which are part of olhs and which have to be excluded before a final diagnosis .
moebius syndrome would also have chest wall abnormalities and paralysis of vi and vii cranial nerves , while hanhart syndrome would be associated with hearing loss .
glossopalatine ankylosis syndrome would also have cleft palate and an intraoral band attaching tongue to palate or maxillary alveolar ridge .
splenogonadal fusion syndrome would be associated with spleen that is abnormally connected to gonads along with cardiac defects , pulmonary hypoplasia , and anorectal atresia .
charlie m syndrome would typically be also associated with urinary obstruction , pulmonary hypoplasia , and cleft palate .
the diagnostic work up would , therefore , include a thorough extra- and intra - oral examination along with referral to ent , medicine , cardiology , urology , and gastroenterology departments .
cranial nerve examination , taste testing , and audiometry should be carried out to rule out any neurological functional defects .
radiographic examination should include the jaws ( orthopantomograph ( opg ) , lateral cephalogram ) , chest , and limbs .
three - dimensional imaging ( cone beam computed tomography ( cbct ) ) can be used to better visualize the craniofacial skeletal defects .
the tongue plays an important role in suckling , speech , mastication , swallowing , taste perception , and development of jaws and occlusion .
it also affects jaw development , facial aesthetics , and hence psychological , sexual , and social development .
ac is associated with difficulty in performing these functions , especially suckling after birth , and has mostly resulted in death of the newborn within 3 days .
taste perceptions are not severely compromised , probably due to presence of taste buds in the mucosa of the floor of the mouth .
speech development is delayed and slurred , and lingual consonants are most affected . in this case , the patient 's speech was near normal and gave no indication that there was aglossia . this remarkable adaptation is made possible by the hypertrophy of the muscles of the floor of the mouth , especially the mylohyoid , due to constant stimulation during swallowing from early life .
this helps the patient in elevating the floor of the mouth to touch the palate , which then mimics the absent tongue and helps in phonation , mastication , and swallowing .
the hypertrophied uvula helps in closing the oropharyngeal opening and forces the air through the nasal passage making the articulation of nasalized sounds possible .
the adaptive mechanisms developed by these patients to compensate for absence of the tongue can be used in rehabilitation of patients who have acquired aglossia due to other causes like surgery for malignancy and trauma .
most cases of ac report characteristic facies with lingually collapsed mandibular arch , further exaggerated due to missing teeth , especially the mandibular incisors .
this patient also had characteristic facial features and oligodontia , which included the mandibular incisors but the mandibular transverse arch deficiency was only limited to anterior region , probably because of the action of hypertrophied mylohyoid muscle , which compensated for the absent tongue during mandibular arch development .
the acquired adaptive mechanism may have reduced the severity of mandibular transverse arch deficiency in this patient .
low caries activity in maxillary teeth has been reported in ac , but this patient had a high caries activity and periodontal disease leading to early loss of remaining teeth and radicular cyst formation .
the susceptibility towards caries and periodontitis could be due to lack of cleansing action of the tongue .
cleft palate has been reported in association with aglossia but a median groove without bony cleft as seen in this case has not been reported before .
erenberg and nowak reported palatal grooving in 47.6% of predominantly premature infants who had required orotracheal intubation .
they defined palatal grooving as  a narrow channel of variable depth located near the midline of the palate . 
procter et al . concluded that palatal grooving is due to overgrowth of lateral palatine ridges and conceded that this may be due to irritation by endotracheal tube in preterm infants or because normal resting tongue posture against the palatal vault is limited by endotracheal tube . in this case , the patient gave no history of endotracheal intubation in the neonatal period .
the movement of the developing tongue plays a role in causing the elevation of the palatal shelves from vertical to horizontal position to form a continuous hard secondary palate during the 8 intrauterine week .
the palatal grooving in this patient could be due to overgrowth of lateral palatine ridges due to absence of tongue during secondary palate development .
functional and aesthetic rehabilitation of patients with aglossia is difficult and requires multidisciplinary and multistep approach .
surgical reconstruction of the tongue is not a priority as the patients show functional adaptation to most functions except speech .
speech therapy is required in early stages as most of the times speech is delayed and slurred .
expansion of collapsed mandibular arch and its retention is difficult , and uses of modified palatal expanders often worsen the swallowing and speech function . distraction osteogenesis following symphyseal osteotomy and use of rapid prototyping models for making custom made ( tooth - borne or bone - borne ) distractors and determining distraction vector has been found to be an useful alternative for mandibular expansion .
prosthetic rehabilitation with fixed / removal appliances or implant - supported prosthesis can be considered where sufficient bone height and width is available . in this case , the mandibular alveolar bone height was greatly reduced and ridge augmentation with autologous bone graft would be required before prosthetic consideration .
early diagnosis , sustained care , and multidisciplinary approach to management and rehabilitation are required right from birth for survival of the patient .
aglossia congenita ( ac ) , congenital total absence of the tongue , is a very rare midline developmental anomaly , hypothesized to be associated with vascular disruption between the fourth and eighth week of gestation . 
 it was classified by hall ( 1971 ) as part of oromandibular limb hypogenesis syndrome ( olhs ) type i b. most of the cases reported with olhs are actually hypoglossia with limb abnormalities whereas isolated aglossia is an extremely rare entity . 
 a case of isolated ac is presented in a 28-year - old indian male . 
 he had long narrow face , tapering chin , low set ears , and microstomia . 
 intraorally , he had narrow palatal vault , constricted oropharyngeal isthmus , oligodontia , and maxillo - mandibular hypoplasia . 
 interestingly , the patient showed a median palatal groove , which has not been reported before . 
 he also had an unusual acquired adaptive mechanism to compensate for aglossia . 
 this report presents the manifestations of this rare syndrome , its complications , differential diagnosis , and rehabilitation strategies .