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GeneReviews((R))-/-? 1993[]; ? (?): ? PMID41343689show ga
CLINICAL CHARACTERISTICS: USP7-related Hao-Fountain syndrome is characterized by developmental delay in 100% of individuals, although intellectual disability is variable, with up to 50% of affected individuals having intellect in the normal range. Muscular hypotonia is also common; this tends to improve over time, but some affected individuals develop hypertonia. About two thirds of affected individuals have an abnormal/unsteady gait and about one quarter have contractures, most commonly involving large joints and joints of the lower extremities. Neuropsychiatric features can include autism, attention-deficit/hyperactivity disorder (ADHD), and behavioral issues such as stubbornness and compulsivity. Feeding difficulties are common and can require special feeding techniques, including use of a feeding tube. Gastroesophageal reflux disease, dysphagia, and hyperphagia have also been reported. Eye and vision issues (hyperopia, strabismus, nystagmus) are seen in more than 50% of affected individuals. About half of affected individuals have impaired bone mineralization, which can lead to fractures. Findings in fewer than 50% of individuals include epilepsy, sleep disturbance, hypogonadism, scoliosis, and hearing loss. DIAGNOSIS/TESTING: The diagnosis of USP7-related Hao-Fountain syndrome is established in a proband with suggestive findings and a heterozygous pathogenic variant in USP7 identified by molecular genetic testing. MANAGEMENT: Treatment of manifestations: Feeding therapy for poor weight gain / dysphagia; gastrostomy tube placement may be required for persistent feeding issues; consultation with a dietician when hyperphagia and/or obesity is present; adequate intake of Ca(2+) and vitamin D for reduced bone mineral density. Standard treatment for developmental delay / intellectual disability, epilepsy, gastroesophageal reflux disease, diarrhea, constipation, eye issues, sleep disturbance, cryptorchidism, micropenis, hypothyroidism, growth hormone deficiency, adrenal insufficiency, and hearing loss. Surveillance: At each visit, measure growth parameters; evaluate nutritional status and safety of oral intake; monitor for signs/symptoms of constipation and gastroesophageal reflux disease; monitor those with seizures; assess for new manifestations such as seizures, changes in tone, and gait abnormalities; monitor developmental progress and educational needs; monitor for scoliosis, contractures, mobility, and self-help skills; monitor for evidence of aspiration, respiratory insufficiency, and sleep disturbance (including for signs/symptoms of sleep apnea); monitor for signs and symptoms of puberty starting at about age seven years to the late teenage years. Annually, behavioral assessment for anxiety, ADHD, autism spectrum disorder, aggression, and self-injury; evaluate for hypothyroidism; audiology evaluation (in childhood). Assess bone mineral density every two years starting at age five years and then every three to five years in adulthood. Ophthalmology evaluation and endocrinologic tests for adrenal insufficiency as clinically indicated. GENETIC COUNSELING: USP7-related Hao-Fountain syndrome is an autosomal dominant disorder typically caused by a de novo pathogenic variant. Rarely, individuals diagnosed with USP7-related Hao-Fountain syndrome inherited a pathogenic variant from a parent. Each child of an individual with USP7-related Hao-Fountain syndrome has a 50% chance of inheriting the pathogenic variant. Once the USP7 pathogenic variant has been identified in an affected family member, prenatal and preimplantation genetic testing are possible.
GeneReviews((R))-/-? 1993 ; ? (?): ?
