49,XXXYY syndrome

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49,XXXYY syndrome

ORPHA:261534Malformation syndrome

What it is

49,XXXYY syndrome is a rare gonosome anomaly syndrome characterized by a eunuchoid habitus with gynecoid fat distribution and shape, normal to tall stature, moderate to severe intellectual disability, distinctive facial features (e.g. prominent forehead, epicanthic folds, broad nasal bridge, prognathism), gynecomastia, hypogonadism, cryptorchidism, small penis and behavioral abnormalities (incl. solitary, passive disposition but prone to aggressive outbursts, autistic). Skeletal malformations, such as delayed bone age, fifth finger clinodactyly, elbow malformations and slow molar development, may also be associated.

Key facts

Prevalence
<1 / 1 000 000
Age of onset
Neonatal
Classified as
Malformation syndrome

Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.

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

Q98.8filed under a broader ICD-10 category — shared with 4 other rare diseases

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.

Related health topics

Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.

Cross-references

GARD 10922MONDO 0016854UMLS C4749586

Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.

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