Down syndrome with co-occurring Marfan syndrome

Abstract

Down syndrome (DS) and Marfan syndrome (MFS) are two unique genetic disorders that share limited phenotypic overlap. There are very few reported cases in the existing literature on overlapping DS and MFS. Although these two disorders are phenotypically unique, features present in these cases are variable, resulting in mixed and dominant expressions of particular features. We present the first adolescent case of trisomy 21 associated DS and fibrillin-1 gene associated MFS in the literature who had a height at 90th percentile for an 11-year old boy and discuss the implications of this case in terms of future medical care when these two genetic syndromes are present in the same individual. Understanding of certain features of the 'non-dominating' syndrome is crucial for clinicians to recognise when DS co-occurs with MFS. Close monitoring of the cardiovascular, ophthalmologic and musculoskeletal systems is recommended if both syndromes are diagnosed given that both can be independently associated with disorders in these organ systems.

Keywords: neurology (drugs and medicines); paediatrics (drugs and medicines).

Figure 1

Phenotypic manifestations: (A) Small and upslanting palpebral fissures, smooth philtrum and micrognathia (consistent with DS); enophthalmos, elongated facies and no epicanthal folds (consistent with MFS). (B) Lack of brachydactyly, clinodactyly and single transverse palmar crease (observed in persons with DS). (C) Steinberg or thumb sign (when folded across palm, the distal phalanx of the thumb fully extends beyond the ulnar border of the hand). MRI images: (D) Axial T1 image demonstrating diffuse corticala trophy, diminished quantity of the white matter volume and mild-moderate thinning of the corpus callosum. (E) Axial T1 image demonstrating prominent extra-axial spaces at the anterior temporal lobes and ex vacuo ventriculomegaly. Orbital vault is small, consistent with multiple prior ophthalmologic comorbidities. Patient’s growth charts: (F) Height growth chart (90th percentile at 11 years of age). (G) Weight growth chart (>97th percentile at 11 years of age). Not pictured: pectus excavatum is poorly visualised due to obesity. DS, Down syndrome; MFS, Marfan syndrome.