Severe clinical presentation in monozygotic twins with 10p15.3 microdeletion syndrome.

Submicroscopic deletion of 10p15.3 is a rare genetic disorder, currently reported in 21 unrelated patients. It is mainly associated with cognitive deficits, speech disorders, motor delay and hypotonia. The size of the deleted region ranges between 0.15 and 4 Mb and does not generally correlate with phenotype. A monozygotic female twin pair with a de novo 2.7 Mb deletion of 10p15.3 is herein reported. The girls presented at the age of 8 months with severe developmental delay and failure to thrive since the first month of life. Their perinatal and family history was unremarkable. On admission they both exhibited generalized dystonia, microcephaly, complete absence of voluntary movements and visual/auditory unresponsiveness. Their brain MRIs demonstrated dilatation of ventricles, subarachnoid spaces and anterior interhemispheric fissure and sylvian fissures bilaterally. Cranial radiography revealed partial fusion of both coronal sutures. Visual and brainstem auditory evoked potentials were markedly abnormal, indicating severe visual and sensorineural hearing impairment. The electroencephalogram, as well as a screening for inborn errors of metabolism, were unremarkable. Both patients required gastrostomy and tracheostomy before the age of 1 year. They were, additionally, managed with physical therapy, as well as baclofen and low-dose haloperidol. Their current state at the age of 2 years is relatively stable. The index patients' phenotype includes features, such as dystonic cerebral palsy, visual and sensorineural hearing impairment or craniosynostosis, which have not been previously reported in individuals with 10p15.3 deletion. It is necessary to consider these novel clinical features and investigate their possible relationship with the recently recognized syndrome.