Pentasomy X syndrome

What it is

A rare sex-chromosome number anomaly characterized by the presence of five X chromosomes in females instead of the usual two. Patients present with global developmental delay, intellectual disability, musculoskeletal abnormalities (mostly small hands and feet, camptodactyly, clinodactyly, radioulnar synostosis), and craniofacial anomalies (such as microcephaly, plagiocephaly, upslanting palpebral fissures, hypertelorism, flat nasal bridge, ear malformations, microganthia). Cardiovascular malformations can sometimes be present as well as immunoglobulin anomalies and an increased susceptibility to infections. External genitalia are generally normal but gonadal dysfunction has been reported.

Key facts

Age of onset

Neonatal

Classified as

Malformation syndrome

Signs and symptoms

These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.

ICD-10 codes

ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.

Cross-references