Verhoeven WMA, Bon BV, Egger JIM, Hoischen A, Doelman JC. An adult female patient with ring chromosome 21: behavioural phenotype and results of high-resolution molecular characterisation.
A female adult patient with mild to moderate mental retardation and minor dysmorphisms was referred for neuropsychiatric examination because of psychotic and autistic symptoms and impulsive behaviours.
Standardized neuropsychiatric and neuropsychological assessment as well as detailed somatic and neurological examination was performed. For genetic analysis, karyotyping, whole genome array analysis, and high-resolution detailed analysis of chromosome 21 were carried through.
Karyotyping showed a de novo ring chromosome 21: 46,XX,der(21)r(21)(p11q22.3). High-resolution array analysis demonstrated a complex aberration consisting of an interstitial duplication in 21q21.1, an interstitial deletion in 21q22.2q22.3, an interstitial deletion in 21q22.3 and a terminal deletion of 21q22.3. Apart from mild dysmorphisms, visual and auditory impairments, and infertility, no somatic or neurological abnormalities were found. A formal psychiatric diagnosis could not be established. The behavioural problems and the supposed psychiatric symptoms could be related to her disharmonic social cognitive profile. The behaviour normalized after the patient returned to a stable and structured living environment.
High-resolution micro-array analysis techniques are essential to substantiate the genotype–phenotype correlation in patients with r(21) and other genetic disorders. Moreover, the results of this study stress the importance of the recognition of alexithymia as a potential cause for behavioural problems and psychiatric symptoms in patients with mental retardation in general.