Social anxiety in individuals with FXS is related to challenges with face encoding, the ability to recognize a face that one has seen before.It appears that individuals with FXS are interested in social interaction and display greater empathy than groups with other causes of intellectual disability, but display anxiety and withdrawal when placed in unfamiliar situations with unfamiliar people. This may range from mild social withdrawal, which is predominantly associated with shyness, to severe social withdrawal, which may be associated with co-existing autism spectrum disorder.Females with FXS frequently display shyness, social anxiety and social avoidance or withdrawal. In addition, premutation in females has been found to be associated with social anxiety. Female individuals with FXS show decreased activation in the prefrontal regions of the brain. Mental health
Attention deficit hyperactivity disorder (ADHD) is found in the majority of males with FXS and 30% of females, making it the most common psychiatric diagnosis in those with FXS. Children with fragile X have very short attention spans, are hyperactive, and show hypersensitivity to visual, auditory, tactile, and olfactory stimuli. These children have difficulty in large crowds due to the loud noises and this can lead to tantrums due to hyperarousal. Hyperactivity and disruptive behavior peak in the preschool years and then gradually decline with age, although inattentive symptoms are generally lifelong.Aside from the characteristic social phobia features, a range of other anxiety symptoms are very commonly associated with FXS, with symptoms typically spanning a number of psychiatric diagnoses but not fulfilling any of the criteria in full.
Myxoid variant: Loose, basophilic matrix, with thick fibrous septa, and foamy histiocytes
Lipoma-like variant: Univacuolated lipocytes, with only isolated hibernoma cells
Spindle cell variant: Spindle cell lipoma combined with hibernoma

Histochemistry
Oil Red O-positive droplets of cytoplasmic lipid can be seen in most cases

Immunohistochemistry
The neoplastic cells are S100 protein positive (approximately 80%), and show membrane and vacuole CD31 immunoreactivity. Uncoupling protein 1 (UCP1), a unique brown fat mitochondrial protein, is also positive. Cytogenetics
There are structural rearrangements of 11q13-21, which are considered most characteristic. This alteration can be detected by metaphase fluorescent in situ hybridization (FISH). MEN1 gene (11q13.1) is most frequently deleted, while GARP gene (11q13.5) may also be involved. Cytology
The fine needle aspiration smears show small, round, brown fat-like cells, with uniform, small cytoplasmic vacuoles and regular, small, round nuclei. There is usually a rich vascular background of branching capillaries. It is not uncommon to also have mature fat cells. Differential diagnoses
It is important to separate hiberoma from adult rhabdomyoma, a granular cell tumor and a true liposarcoma. Classification
This lesion has been called a fetal lipoma, lipoma of embryonic fat or a lipoma of immature fat. Management
Complete surgical excision is the treatment of choice, associated with an excellent long term clinical outcome. Epidemiology
The tumor is rare, affecting adults in the 4th decade most commonly. Patients are usually younger than those who present with a lipoma. There is a slight male predominance. Hibernoma are most commonly identified in the subcutaneous and muscle tissue of the head and neck region (shoulders, neck, scapular), followed by thigh, back, chest, abdomen, and arms.