A rare chromosomal disorder manifested by the presence of five X chromosomes leading to short stature, mental retardation, fifth finger clinodactyly, short neck, microcephaly, cardiac anomalies (ventricular septal defect, atrial septal defect, patent ductus arteriosus), and horseshoe kidneys. Onset is during childhood.
XXXXX Syndrome; Pentasomy X; 49XXXXX Syndrome.
First described by Kesaree and Wooley in 1963.
The X chromosomes are of maternal origin. Risk factors for females only. The incidence is rare, less than 50 cases reported. The pathogenesis is believed to be a result of successive nondisjunctive meiotic divisions within the mother.
Prenatal onset growth deficiency with failure to thrive and short stature. Microcephaly with upward slant of palpebral fissures and hypertelorism. Seizure activity has been reported in 20% of patients without abnormal brain function (MRI and EEG). Low nasal bridge, short neck. Small hands with clinodactyly of the fifth finger. Forty percent of patients are known to have congenital heart defect: ventricular septal defect, conotruncal or patent ductus arteriosus. Premature loss of deciduous teeth. Moderate to severe mental retardation. Occasional findings include coloboma of the iris, myopia, micropthalmus, and optic nerve hypoplasia (15%). Macroglossia, cleft palate, micrognathia, low-set ears, clubfeet, multiple joint dislocation, renal dysplasia, and horseshoe kidney (10%). Usually associated with equinovarus, overlapping toes, multiple joint dislocations (shoulder, elbow, hip, wrist, and finger), and radioulnar synostosis. Prenatal diagnosis is possible.
Precautions before anesthesia
Check renal function and cardiac anatomy. A cardiac echocardiography might be indicated.
The association of micrognathia with macroglossia could lead to difficult airway management. Careful positioning to avoid joint dislocation. Specific considerations will be dictated by the cardiac and renal anomalies.
Antibiotic prophylaxis may be indicated in case of cardiac defect.
A: Sex chromosome tetrasomy and pentasomy. Pediatrics
et al: A new case of prenatally diagnosed pentasomy X: Review of the literature. Case Rep Obstet Gynecol