Down syndrome: clinical profile from India

Our objective was to study demographic features, clinical features, and karyotype analyses of patients with Down syndrome (DS). Our study design was a retrospective analysis, while the study was conducted in the Genetic Clinic of a tertiary-care teaching hospital.

Retrospective analysis of cases referred to the Genetic Clinic was performed. Case proformas of the patients presenting with phenotypic features of DS were analyzed. The following information was recorded from the proformas: age at presentation; sex; maternal age; craniofacial and other physical features; presence and type of congenital heart disease; gastrointestinal abnormalities, and results of cytogenetic evaluation. Clinical features in neonates with DS were separately analyzed.

Analysis included cases of DS presenting over a period of 7.5 years; a total of 524 patients were studied (303 males and 221 females; M:F ratio 1.37:1). Average age at presentation was 19.4 months (range: 1 day-26 years). Average maternal age at birth of the affected child was 26.8 years (range: 16-45 years). Craniofacial features noted in >50% of the cases included mongoloid slant (83.9%), ear abnormalities (66.9%), epicanthic folds (56.9%), and flat facial profile (50.9%). A total of 76.3% cases had hypotonia. Characteristic limb and dermatoglyphic anomalies were seen in less than one half of cases. These included sandle sign (46.2%), unilateral or bilateral simian crease (33.2%), clinodactyly (36.1%), and brachydactyly (11.1%). Ophthalmologic abnormalities included hypertelorism (33.9%), nystagmus (3.2%), Brushfield spots (3.2%), squint (2.7%), and cataracts (1.9%). Congenital heart disease was clinically diagnosed in 96 cases (18.3%). The nature of the cardiac defect was ascertained by color Doppler examination and/or 2D-echocardiography in 58 cases. The most common cardiac anomalies were ventricular septal defect (25.8%), tetralogy of Fallot (15.5%), and atrial septal defect (12.1%). Gastrointestinal anomalies were noted in seven cases and included three cases with imperforate anus, two with Hirschsprung disease, and one each with duodenal atresia and Morgagni hernia. Results of cytogenetic abnormalities were available in 42.2%. Free trisomy (non-dysjunction) was present in 95%, 3.2% had translocation, and 1.8% were mosaics. In neonates, common features noted were mongoloid slant, ear abnormalities, flat facial profile, hypotonia, sandle sign, and clinodactyly+/-brachydactyly.

All characteristic craniofacial and physical features of DS need not be present in every case. Major features noted in the present study were mongoloid slant, ear abnormalities, epicanthic folds, flat facies, and hypotonia. Congenital heart disease was present in 18.3% of cases, with ventricular septal defect being the most common type of defect. Non-dysjunction was the most common cause of the chromosomal anomaly.