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X-linked recessive syndrome characterized by severe mental retardation, seizures, deafness, failure to thrive, microgenitalism, and early death.

Juberg-Marsidi Mental Retardation Syndrome; X-Linked Microcephaly.

Incidence is unknown because only a few cases have been reported in the literature. X-linked recessive at the Xq12-q21 site. The syndrome has clinical similarities with the ATR-X syndrome (alpha-thalassemia, mental retardation, X-linked syndrome), which is associated with mutations of the X-linked nuclear protein (XNP) gene.

Clinical manifestations of this syndrome are apparent at birth or within the first few weeks of life. Moderate-to-severe mental retardation with developmental delay; hypotonicity; occasionally EEG abnormalities, clinical seizures, hearing loss, and microcephaly. Facial dysmorphism such as a flattened nose, high arched palate, ocular abnormalities, and telecanthus are frequent. Short stature secondary to delayed bone growth. Congenital heart disease has been reported but may not be systematically included in this condition. Genitourinary abnormalities, including undescended/atrophic testes and micropenis, are common. Other features include onychodystrophy and delayed bone age. The range and severity of symptoms vary among cases. Usually fatal in infancy or childhood.

Seizure control and potential interactions between anesthetic drugs and antiseizure medications (e.g., phenytoin and carbamazepine may increase nondepolarizing muscle relaxant requirements.). Antiseizure medication should be continued throughout the perioperative period. Severe muscle hypotonicity may predispose to perioperative respiratory insufficiency; consider judicious use of muscle relaxants. Consider an echocardiogram to rule out congenital heart disease. Renal function should be evaluated because of occasional incidence of hydronephrosis. Perhaps at risk for recurrent urinary tract infections.

ATR-X Syndrome: Acronym for alpha-thalassemia, mental retardation, X-linked syndrome. Characterized by genital abnormalities, microcephaly, midface hypoplasia, severe mental retardation, neuromotor dysfunction, seizures, and hypotonia. Occasionally the patient presents a ventricular septal defect and gastrointestinal reflux.

Allan-Herndon Syndrome: Although most neonates and infants with this disorder appear to develop normally in the first few months of life, the presence of poor muscle tone is most often present at birth. By 6 months of age, hypotonia, inability to hold up the head, and severe muscle atrophy are detectable. Severe mental retardation is associated with multiple congenital anomalies.

Fragile X Syndrome: Most common form of X-linked mental retardation; affects males more often and more severely than females. Only subtle dysmorphic features, but behavioral issues may be more pronounced.

Happy Puppet Syndrome: Rare disorder characterized by developmental delay, ataxia, dysmorphic facial features, and seizures associated with a happy, sociable disposition.

MASA Syndrome: Acronym for mental retardation, aphasia, shuffling gait and adducted thumbs. Extremely rare inherited disorder that is one of several disorders known as X-linked mental retardation (XLMR) syndromes.

Renpenning Syndrome: Extremely rare form of X-linked (moderate-to-severe) mental retardation. Has been linked to Xp11.2-p11.4. Other findings may include short stature, moderate microcephaly, prognathism, and small testes. Affected patients may use repetitive speech and show ...

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