Nguyen Syndrome

Clinical Features

Nguyen et al. (2003) described a patient followed from the age of 15 months to 20 years who had severe growth retardation, obesity, hypotonia in infancy, microcephaly with hypoplastic frontal lobes on CT scan, severe cognitive impairment with behavior disturbance, minor facial anomalies including epicanthal folds, a short nose with low nasal bridge and anteverted nares, and a high-arched palate, bilateral camptodactyly of fingers 4 and 5, and bilateral partial cutaneous syndactyly of toes 2 and 3. He had cryptorchidism and hypoplastic scrotum in infancy but later developed normal external genitalia. Nguyen et al. (2003) noted that the phenotype resembled that of Smith-Lemli-Opitz syndrome (SLOS; 270400); biochemical investigations of sterol metabolism revealed profound hypocholesterolemia but no accumulation of 7-dehydrocholesterol precursor, and low LDL cholesterol and apolipoprotein B (107730) levels. The boy's asymptomatic father and the father's asymptomatic brother had the same pattern of biochemical abnormalities; the mother was biochemically normal. Nguyen et al. (2003) proposed that the boy's clinical manifestations represented an MCA/MR syndrome with hypocholesterolemia due to autosomal dominant hypobetalipoproteinemia.

Nakane et al. (2005) reported a 13-year-old boy with hypobetalipoproteinemia who had a SLOS-like phenotype including mental retardation and a characteristic facies resembling that of the patient described by Nguyen et al. (2003). The unaffected father had a biochemical profile similar to that of the patient with hypocholesterolemia, hypotriglyceridemia, low LDL cholesterol, and apolipoprotein B. An unaffected brother also had hypocholesterolemia; the mother was biochemically normal. Nakane et al. (2005) concluded that this patient represented a second case of Nguyen syndrome.