49, XXXYY syndrome

Alternate names

XXXYY syndrome

Definition

49, XXXYY syndrome is a chromosome abnormality that occurs when a male inherits two extra copies of the X chromosome and one extra copy of the Y chromosome.

Epidemiology

The condition is extremely rare with only a handful of cases reported in the medical literature.

Cause

49, XXXYY syndrome is likely caused by a mistake (called nondisjunction) that occurs at conception or during the formation of the sperm and/or egg.

Signs and symptoms

Signs and symptoms associated with these cases include severe intellectual disability, distinctive facial features, normal to tall stature, gynecomastia, hypogonadism, and behavioral abnormalities.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Abnormal facial shape(Unusual facial appearance)
• Abnormal plantar dermatoglyphics(Abnormal prints on feet)
• Abnormality of the cerebral white matter
• Ambiguous genitalia(Ambiguous external genitalia)
• Autistic behavior
• Bilateral talipes equinovarus(Club foot on both sides)
• Decreased serum testosterone level(Decreased serum testosterone levels)
• Decreased testicular size(Small testes)
• Delayed skeletal maturation(Delayed bone maturation)
• Delayed speech and language development(Deficiency of speech development)
• Epicanthus(Eye folds)
• Eunuchoid habitus
• Finger clinodactyly
• Gynecomastia(Enlarged male breast)
• Hypertelorism(Wide-set eyes)
• Increased circulating gonadotropin level(Elevated gonadotropins)
• Intellectual disability(Mental deficiency)
• Low frustration tolerance
• Low-set, posteriorly rotated ears
• Male hypogonadism(Decreased function of male gonad)
• Mandibular prognathia(Big lower jaw)
• Micrognathia(Little lower jaw)
• Micropenis(Short penis)
• Moderate global developmental delay
• Narrow chest(Low chest circumference)
• Primary gonadal insufficiency
• Prominent forehead(Pronounced forehead)
• Recurrent upper respiratory tract infections(Recurrent colds)
• Ventriculomegaly
• Wide nasal bridge(Broad nasal bridge)

Diagnosis

Chromosome disorders may be suspected in people who have developmental delays, intellectual disabilities and/or physical abnormalities.

Several types of genetic tests can identify chromosome disorders:

• Karyotyping
• Microarray (also called array CGH)
• Fluorescence in situ hybridization (FISH)

Treatment

Treatment is based on the signs and symptoms present in each person.

NIH genetic and rare disease info

• NIH info on 49, XXXYY syndrome

49, XXXYY syndrome is a rare disease.

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