Emotional lability as a leading symptom of tetrasomy 18p in a 7-year-old girl with developmental delay, hypertonus of the adductors, kyphosis and facial anomalies

Aims: Isochromosomes 18p result in tetrasomy 18p that are usually due to de novo formation. The occurrence is supposed to be once in every 140000 livebirths.

Case report: After normal pregnancy and birth the child was admitted to our hospital at the age of 3 months for the first time because of failure to thrive and delopmental delay. Growth charts showed a decline from P75 to P23 from birth until the age of 7, weight a decline from P25 to < P3 and head circumference from P50 to < P3. Facial dysmorphic features: hypotelorism, narrow palpebral fissure, smooth philtrum, hypoplastic alar wings of the nose and high arched palate. Additionally kyphosis and remarked muscular hypertonus of the adductors of the legs with coxa valga. MRI of the brain revealed diffuse, spotty subcortical hyperintensities especially in FLAIR sequence. Chromosomal analysis presented a de novo isochromosome 18p (FISH 47,XX,+i(18p)).

The girl was able to walk from the age of 20 months. At present (at the age of 7) she speaks short sentences. The psychosocial development it is remarkable: the girl presents periods of pronounced affect weakness with persistent screaming without an identifiable trigger that alternate within seconds with laughing bouts.

Discussion: Developmental delay plus spasticity directs usually towards infantile cerebral palsy. However; it is also a reported sign of the phenotypically variable tetrasomy 18p. The extraordinary emotional lability is remarkable in our patient. Associated behavioral problems demand a special management of the support and the treatment of affected patients and families.