Phenotypic Features and Inheritance Pattern of Emanuel Syndrome: An Indian Perspective

Abstract

Aim and objective: To study the phenotypic features and inheritance patterns in children diagnosed with Emanuel syndrome (ES). Materials and methods: All children who underwent cytogenetic analysis at the Christian Medical College, Vellore and whose karyotypes showed the supernumerary chromosome 22 derived from an unbalanced translocation (11;22)(q23;q11.2) were included. Karyotypes of family members were retrieved from hospital records. Metaphases were obtained from phytohemagglutinin-stimulated peripheral blood cultured using standard protocols. At least 20 Giemsa-banded metaphases were analyzed and reported in accordance with the International System for Human Cytogenomic Nomenclature. The clinical features and imaging findings were retrieved from our medical records. The karyotype findings of parents and family history including the obstetric history of all mothers were recorded. Results: There were eight children, three girls and five boys, all of whom were from unrelated families. The age at presentation ranged from 8 months to 8 years of age. Three families presented with significant family history in the form of previous sibling deaths, recurrent abortions in the mother, and maternal siblings’ death. All eight children presented with global developmental delay. Preauricular sinus was found in six children (6/8,75%), while microcephaly and hypotonia in five each (5/8,62.5%). More than half of our children presented with structural cardiac and brain malformations. In three children, the der(22) was found to have originated from a maternal source of the t(11;22). All three mothers who harbored this translocation were phenotypically normal. Conclusion: The characteristic clinical features of ES found in our study included preauricular sinus, microcephaly, hypotonia, cardiac defects, and structural brain malformations. The maternal source of the t(11;22) was the commonest mode of inheritance among children diagnosed with ES. Clinical significance: Emanuel syndrome is a rare syndrome and it is extremely important to identify the phenotypic features of this clinical entity since early intervention can aid in appropriate counselling and offering prenatal testing. The majority of children diagnosed with ES were found to have inherited this genetic defect due to a translocation (11;22) running in the family. Hence, a clear understanding of the reproductive outcomes of the t(11;22) is of vital importance in counseling the family members and offering prenatal testing.