Background Children with Down syndrome have different saliva composition compared to normal children. The presence or absence of the salivary glands has not been previously reported.
Objective To examine the presence or absence of the salivary glands in children with Down syndrome.
Methods 15 children with Down syndrome underwent an ultrasound examination of the salivary glands. The control group consisted of 31 healthy children. The areas of the parotid and submandibular glands on both sides were scanned in an attempt to demonstrate all four glands. The result was reported as ‘present’ or ‘absent’.
Results In four children out of 15 with Down syndrome, one or more salivary glands were absent (26.7%), while in the controls all salivary glands were present. The difference between the groups was statistically significant (p=0.008). There was no significant difference between the groups regarding age and sex.
Conclusions At least one salivary gland is undetected by ultrasound in some children with Down syndrome.
- Congenital Abnorm
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What is already known on this topic
The saliva composition of children with Down syndrome is different from normal children. One case report of congenital absence of salivary gland in Down syndrome has been reported.
What this study adds
We found that about 27% children with Down syndrome have congenital absence of one or more salivary glands. This finding may be used in prenatal diagnosis of Down syndrome.
Congenital absence of the salivary glands is rare, and has been reported in a few cases in normal children and in children with Down syndrome.1 ,2 Higher protein and sodium concentration, and lower flow of saliva, amylase, peroxidase activities and potassium concentration, were reported in children aged 12–60 months with Down syndrome.3 We have previously reported the normal appearance of the parotid and submandibular salivary glands in normal foetuses between 14 and 16 weeks of gestation using transvaginal ultrasound.4
Congenital absence of the salivary glands has not been studied in children with Down syndrome. The facts that these glands can be sonographically demonstrated at early pregnancy stages and that children with Down syndrome have different saliva composition prompted us to study the prevalence of congenital absence of the salivary glands, in normal children and in those with Down syndrome.
Children with Down syndrome followed up at our institution were called for ultrasound of the salivary glands, and written informed consent was obtained from every child’s parents. The ultrasound was performed by single operator experienced with ultrasound of small parts (MH) using a 10 Mhz linear transducer (GE Logiq 9, General Electric Company, Wauwatosa, Wisconsin, USA). The control group consisted of children hospitalised or at follow-up at our institution for conditions not involving the salivary glands, and whose parents gave consent for participation.
The areas of the parotid and the submandibular glands were scanned carefully on both sides and the result was reported as present if the gland was observed and absent if it was not.
Quantitative data were compared using the Wilcoxon rank sum test; qualitative data were analysed using the χ2 test or Fisher exact test as appropriate. A p value <0.05 was considered statistically significant. The data were analysed using SPSS V.19.
Of 27 children with Down syndrome on follow-up, the parents of 15 consented to the examination (table 1). The control group consisted of 31 children without Down syndrome and any condition affecting the salivary glands. There was no difference between the groups regarding age and gender (table 2).
In the control group all children had intact, normal parotid and submandibular salivary glands (figures 1 and 2). In the Down syndrome group the submandibular gland was unilaterally absent in three children and bilaterally absent in one child (figure 3).
The parotid gland was very small in three of the Down syndrome group; however, one of these children had suffered severe facial burns and scarring which may have contributed to shrinkage of the parotid gland. Of the other two children, one had bilaterally small parotid and submandibular glands, and the second had bilaterally small submandibular glands. However, since the original protocol of the study was to report the salivary glands only as absent or present, these three children with small but present parotid glands were included in the ‘present’ group.
Thus in 26.7% (4/15) in the Down syndrome group and in none of the control group, one or more salivary glands was absent; the difference was statistically significant (p=0.008).
In early embryological life, the parotid glands are the first of the three pairs of major salivary glands to develop, at 6 weeks of gestation, followed by the submandibular glands, at the end of the sixth week, and then the sublingual glands, which appear in the eighth week as a series of small ectodermal buds in the floor of the mouth just beneath the tongue.5 ,6 Sonography is a widely accepted tool for evaluation of the salivary glands; CT and MRI are also used.7–9
As far as we know this is the first report of congenital absence of the salivary glands in children with Down syndrome. A limitation of our study is the small population size of 15 children. However, the rarity of congenital absence of one or more salivary glands, and the high percentage in our study group suggests that our finding is significant.
In addition, several children in the Down syndrome group demonstrated small salivary glands.
The findings of this study are important for two reasons. First, congenital absence of the salivary gland may lead to early dental decay.10 Hence, if diagnosed early in life these children might benefit from appropriate early treatment. Second, since we have reported the possible identification of the salivary glands as early as 14 weeks of gestation,4 the absence of one or more salivary glands can be utilised as a marker of Down syndrome, thus increasing the possibility of its prenatal detection.
In conclusion, one or more salivary glands may be absent in children with Down syndrome. The possibility of using this finding as a marker of Down syndrome should be tested in a large population study.
Contributors The first draft of the manuscript was written by MO. All authors have seen and approved the submission of this version of the manuscript and take full responsibility for the manuscript.
Competing interests None.
Patient consent Obtained.
Ethics approval Ethics approval was given by the IRB of Western Galilee Hospital.
Provenance and peer review Not commissioned; externally peer reviewed.
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