Discussion
Agenesis of the corpus callosum is one of the most frequently found structural brain abnormalities with several recognized syndromic correlations and genetic disorders, with an incidence between 0.03 to 0.7% [16]. Polydactyly and agenesis of the corpus callosum are characteristics of acrocallosal syndrome (ACLS). Despite the high incidence of hand and foot polydactyly, preaxial polydactyly of the foot is expected to occur in only 0.4 cases per 10,000 Europeans [17]. Preaxial polydactyly of the foot is related with other congenital anomalies and syndromes, such as craniosynostosis, renal malformations, and also corpus callosum agenesis in ACLS as seen in our patient. ACLS is an extremely rare developmental condition and only roughly forty cases have been reported globally to date [18].
According to the criteria established by Courtens et al in 1997, the diagnosis of ACLS can be made if at least three of the following four criteria are present: 1) Minor craniofacial abnormalities 2) Moderate to severe mental retardation with hypotonia 3) Polydactyly 4) Total or partial absence of the corpus callosum [19]. Polydactyly and agenesis of the corpus callosum and widening of the anterior fontanelle were observable in our patient, but despite the structural abnormalities of the brain, the patient’s neurological exams were normal. Due to the child’s young age, it is currently impossible to form a definitive assessment on his mental development.
The cardiac results are comparable to prior reports of congenital heart diseases found in two other cases. In the report by Casamassima et al., the child diagnosed with ACLS displayed tetralogy of Fallot on echocardiogram and Wolff-Parkinson-White Type B on electrocardiogram [20]. In Singhal et al. report, the echocardiography of the patient with ACLS indicated a small secundum type ASD with moderate tricuspid regurgitation and dextro positioning of the heart. [14]. Considering that ASD was detected by echocardiography in the present study, it is possible that cardiac abnormalities are among the symptoms of this syndrome.
Acrocallosal syndrome, Joubert syndrome, and hydrolethalus fetal syndrome are all caused by a missense mutation in KIF7(15q26.1), a modulator of ciliary Hedgehog signaling [21]. Due to the autosomal recessive inheritance pattern of ACLS, the recurrence risk is 25%, making genetic counseling essential. In our case, the genetic test had revealed that the patient’s parents were healthy. According to the studies, although autosomal recessive inheritance has been proposed, ACLS often tends to happen sporadically [22]. It was also noteworthy that the patient’s mother worked as a hairdresser and had been exposed to chemicals during pregnancy. In a study by Rylander et al., it was determined that a greater proportion of children born to hairdressers suffered major malformations (2.8% vs 2.1%) [23]. However, in previous studies, mostly oral clefts have been linked to mother’s occupation as a hairdresser [24]. On the other hand, laboratory research on mice have demonstrated that exposure to cosmetics-related chemicals including toluene, significantly raises an index of poor perinatal outcome, comprising morphological and marginal neurodevelopmental malformations and newborn mortality [25]. These studies imply that the mother’s exposure to cosmetic-related substances may be a possible cause of the neonate’s abnormalities.