MRI and 1H MRS findings in Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder characterized by a defect in cholesterol biosynthesis, associated with mental retardation and multisystem structural abnormalities. This study investigated the prevalence of congenital CNS abnormalities by MRI in a large series of patients with SLOS and the correlation of the clinical and biochemical findings with the results of MRI and 1H MRS. Eighteen patients were studied; all underwent MRI of the brain, and 16 had 1H MRS of the cerebral white matter. The ratios choline:NAA, lipid:NAA, and lipid:choline metabolite were found to be correlated with the clinical degree of disease severity, serum total sterol ratios (cholesterol/cholesterol + 7-dehydrocholesterol + 8-dehydrocholesterol) and in two cases with the effect of cholesterol therapy. Abnormal CNS findings were noted in five patients, including callosal abnormalities (n = 4), Dandy-Walker variant (n = 1), and arachnoid cyst (n = 1). Holoprosencephaly was noted in one patient with a prevalence of 6%. Choline:NAA was elevated in seven patients. There was a statistically significant positive correlation between the lipid:choline ratio and the serum cholesterol precursor, 8-dehydrocholesterol. In two patients 1H MRS demonstrated abnormally elevated lipids prior to cholesterol therapy, which improved on therapy. The use of MRI and 1H MRS is an effective way to demonstrate brain structural abnormalities in patients with SLOS and may prove to be an effective method for the assessment of the effects of cholesterol replacement therapy in the brain.

Spectrum of Delta(7)-dehydrocholesterol reductase mutations in patients with the Smith-Lemli-Opitz (RSH) syndrome.

The Smith-Lemli-Opitz syndrome (SLOS; also known as the RSH syndrome) is an autosomal recessive genetic disorder, leading to characteristic multi-organ developmental abnormalities, dysmorphic facies, limb malformations and mental retardation. Mutations in the gene for Delta(7)-dehydrocholesterol reductase (Delta(7)-reductase), which catalyzes the last step in cholesterol biosynthesis, cause the disease. We screened 32 patients with SLOS, 28 from the USA and four from Sweden. Twenty-two different nucleotide changes, predicted to be disease-causing mutations, were identified; 20 missense mutations, one nonsense mutation and one splice-site mutation involving the exon 9 acceptor site (IVS8 -1G-->C) were detected. All probands were heterozygous for mutations. Twelve of these mutations have not been reported previously, including missense mutations L148R, F168I, D175H, P179L, P243R, F284L, N287K, F302L, R404S, Y462H, R469P and one nonsense mutation W37X [corrected]. Coupled with previously reported mutations, these findings bring the total of different Delta(7)-reductase mutations to 36. These are distributed throughout the coding sequence of the Delta(7)-reductase gene except exons 3 and 5, with a clustering in exon 9. Three mutations account for 54% of those observed in our cohort, the splice acceptor site mutation IVS8 -1G-->C (22/64 alleles, 34%), T93M (8/64, 12.5%) and V326L (5/64, 7.8%). Severity of SLOS was negatively correlated with both plasma cholesterol and relative plasma cholesterol, but not with 7-dehydrocholesterol, the immediate precursor, confirming previous observations. However, no correlation was observed between mutations and phenotype, suggesting that the degree of severity may be affected by other factors. We estimate that between 33 and 42% of the variation in the SLOS severity score is accounted for by variation in plasma cholesterol. Thus, factors other than plasma cholesterol are additionally involved in determining severity.

The 3C syndrome: evolution of the phenotype and growth hormone deficiency.

The 3C syndrome (cranio-cerebello-cardiac dysplasia or the Ritscher-Schinzel syndrome) is a recently delineated condition involving abnormalities of the cranium (large head with prominent forehead), cerebellum (Dandy-Walker cyst and vermis hypoplasia), and cardiac (primarily septal) defects. At least 20 individuals with this condition have been reported in the past 11 years. We report on a girl with the 3C syndrome who at 13 years of age is the oldest patient reported to date. She has been followed since birth, allowing us to show the evolution of her phenotype over time. In addition, she has documented growth hormone deficiency. We suggest that growth hormone deficiency should be considered as a possible cause of the short stature often seen in this condition.

An interesting case of infant sudden death: severe hypertrophic cardiomyopathy in Pompe's disease.

Glycogen storage disease type II (Pompe's disease) is a rare inherited metabolic disorder, which often leads to infantile death from severe cardiomyopathy. This case of sudden death illustrates the features of the cardiac findings in the disorder, resulting from massive lysosomal accumulation of glycogen in the heart and other tissues. Pompe's disease should be considered in cases of unexplained infantile cardiomyopathy.

Renal findings on radiological followup of patients with Beckwith-Wiedemann syndrome.

PURPOSE: The Beckwith-Wiedemann syndrome is most commonly characterized by macroglossia and abdominal wall defect(s), and it carries a predisposition to embryonal tumors, including Wilms tumor. We report our experience with the character and incidence of renal disease in patients with the Beckwith-Wiedemann syndrome, and discuss the role of radiological followup. MATERIALS AND METHODS: We reviewed the medical records of all patients diagnosed with the Beckwith-Wiedemann syndrome who were treated at our institution between March 1979 and February 1998. Radiological followup consisted of renal ultrasound at approximately 3 to 6-month intervals with the addition of computerized tomography or magnetic resonance imaging (MRI) in patients with an indeterminate lesion(s) or nephrogenic rest(s). RESULTS: A total of 29 patients were identified. Of these cases renal ultrasound showed normal kidneys bilaterally in 19 (70%), simple cysts in 5 (19%), indeterminate lesion(s) in 2 (7%) and nephrocalcinosis in 1 (4%). Nephrogenic rests were followed with MRI in 1 patient, and 1 in whom a 2 cm. mass was revealed by followup MRI underwent partial nephrectomy and chemotherapy for stage I Wilms tumor. CONCLUSIONS: The 3.7% incidence of Wilms tumor in our patients with the Beckwith-Wiedemann syndrome is similar to that in previously published reports. Aggressive follow-up by a sensitive radiological technique is warranted in cases of the Beckwith-Wiedemann syndrome, and associated hemihypertrophy and/or nephromegaly with or without evidence of a Wilms tumor precursor. The detection of suspected malignant disease at an early stage may permit curative nephron sparing surgery.

A new syndrome: heart defects, laryngeal anomalies, preaxial polydactyly, and colonic aganglionosis in sibs.

We present two siblings, one male and one female, who have heart defects, duplication of toes, airway anomalies, and aganglionosis. The brother also has a bilateral complete cleft lip and palate. His airway anomalies include short epiglottis and aryepiglottic folds, which are different from his sister who has a bifid epiglottis with a central epiglottic mass. Both siblings have had some developmental delay. This constellation of anomalies appears to be unique and may represent a new autosomal recessive disorder.

Developmental delay and growth failure caused by a peroxisomal disorder, dihydroxyacetonephosphate acyltransferase (DHAP-AT) deficiency.

We describe a 6 1/2-year-old-girl presenting with a unique phenotype and dihydroxyacetonephosphate acyltransferase (DHAP-AT) deficiency (1.6% of control activity in cultured fibroblasts), a peroxisomal enzyme deficiency which was reported previously to cause rhizomelic chondroplasia punctata (RCDP). Her phenotype is less severe than that seen in classical RCDP, and is notable for short stature, microcataracts, normal limbs, mild hypotonia, and severe mental retardation. Epiphyseal stippling is present. This patient illustrates the variability of peroxisomal disorders whereby a specific defect in peroxisomal plasmalogen synthesis may lead to several phenotypes. Her case also suggests that children presenting with deficient growth, developmental delay, and epiphyseal stippling should be screened carefully for peroxisomal disorders, with measurement of plasmalogens in addition to very long chain fatty acids.

Fetal Smith-Lemli-Opitz syndrome can be detected accurately and reliably by measuring amniotic fluid dehydrocholesterols.

The Smith-Lemli-Opitz syndrome, characterized by limb, face and organ abnormalities, and mental retardation, is caused by an inherited block in the step of cholesterol biosynthesis in which the delta 7 double bond of 7-dehydrocholesterol is reduced. It is diagnosed by the presence of markedly elevated levels of 7-dehydrocholesterol and 8-dehydrocholesterol in plasma and tissue. We measured amniotic fluid sterols in 15 pregnancies in 13 women who had previously carried an affected fetus. Cholesterol, 7-dehydrocholesterol and 8-dehydrocholesterol concentrations averaged 18 +/- 3, 9.8 +/- 2.9 and 5.0 +/- 1.7 micrograms/ml, respectively, in seven pregnancies with an affected fetus or child. In contrast, these levels were 19 +/- 3, 0.05 +/- 0.01 and < 0.005 micrograms/ml, respectively, in eight increased-risk pregnancies with normal outcomes and 16 +/- 2, 0.07 +/- 0.01 and < 0.005 micrograms/ml in normal controls. 7-dehydrocholesterol concentrations, 2.2-26 and 0.05-0.10 micrograms/ml in pregnancies with an affected and unaffected fetus, respectively, did not overlap. Thus, abnormally elevated amniotic fluid dehydrocholesterol concentrations are an accurate predictor of fetal Smith-Lemli-Opitz syndrome. A false-positive or a false-negative result is highly unlikely.

New recessive syndrome characterized by increased chromosomal breakage and several findings which overlap with Fanconi anemia.

We describe four cases with several findings of Fanconi anemia (FA), but without hypersensitivity to DNA cross-linking that is the distinguishing characteristic of FA. Two of the cases are male and female sibs of Hispanic origin, age 6 years and 11 months, respectively. Both have short stature, failure to thrive, absent thumbs, short palpebral fissures, and skin pigmentation abnormalities. The girl also has developmental "dysplasia" of her hips. Presently, both siblings are hematologically normal. Elevated baseline chromosome breakage was observed in the boy, but not in the girl. Neither sib showed elevated diepoxybutane (DEB)-induced chromosomal breakage. In a subsequent pregnancy, prenatal studies showed slightly elevated baseline and DEB induced chromosome breakage (greater than normal, but lower than the established range for FA). The fetus had intrauterine growth retardation and an absent right thumb. A review of cases referred to the International Fanconi Anemia Registry for DEB testing showed one additional case with similar findings. That patient, a girl, of Caucasian English ancestry, age 14 years, had short stature, a history of failure to thrive, skin pigmentation abnormalities, absent right thumb, hypoplastic left thumb, and hydrocephalus that resolved spontaneously. Elevated baseline chromosome breakage was observed in skin fibroblasts but not in lymphocytes. We postulate that these cases represent a previously undescribed autosomal recessive syndrome. These and other previously reported cases provide evidence for alternative genetic mechanisms that may result in developmental anomalies similar to those seen in FA.

Skeletal anomalies and deformities in patients with deletions of 22q11.

Skeletal anomalies in patients with a 22q11.2 deletion are reported infrequently. We report the skeletal findings in 108 patients with a 22q11.2 deletion, of whom 37 (36%) had a skeletal anomaly. Twenty-two patients (20%) had anomalies of the limbs, 7 of the upper limb, including preaxial or postaxial polydactyly. An anomaly of the lower limb was found in 16 patients, including postaxial polydactyly, clubfoot, severely overfolded toes, and 2-3 toe cutaneous syndactyly. Chest films of 63 patients were examined; 30% of them had abnormal findings, most commonly supernumerary ribs (17%) or a "butterfly" vertebral body (11%). Hypoplastic vertebrae, hemivertebrae, and vertebral coronal clefts were also noted. Thus, skeletal anomalies are not uncommon in patients with a 22q11.2 deletion and may occur more frequently than recognized previously.

Clinical effects of cholesterol supplementation in six patients with the Smith-Lemli-Opitz syndrome (SLOS)

We describe the clinical effects of cholesterol supplementation in 6 children with the RSH-"Smith-Lemli-Opitz" syndrome (SLOS). The children ranged in age from birth to 11 years at the onset of therapy, with pretreatment cholesterol levels ranging from 8 to 62 mg/dl. Clinical benefits of therapy were seen in all patients, irrespective of age at onset of treatment, or severity of cholesterol defect. Effects of treatment included improved growth, more rapid developmental progress, and a lessening of problem behaviors. Pubertal progression in older patients, a better tolerance of infection, improvement of gastrointestinal symptoms, and a diminution in photosensitivity and skin rashes were also noted. There were no adverse reactions to treatment with cholesterol. This preliminary study suggests that cholesterol supplementation may be of benefit to patients with the SLOS.

Treatment of Smith-Lemli-Opitz syndrome: results of a multicenter trial.

Patients with the RSH or Smith-Lemli-Optiz syndrome (SLOS) have an inborn error of cholesterol biosynthesis which results in a deficiency of cholesterol and an elevation of the cholesterol precursor, 7-dehydrocholesterol. A treatment protocol consisting of administration of cholesterol +/- bile acids was initiated in an attempt to correct the biochemical abnormalities seen. Fourteen patients (8 female, 6 male: ages 2 months to 15 years) have now been treated for 6-15 months. Three patients received cholesterol alone, while 11 patients received cholesterol and one or more bile acids. Biochemical improvement in sterol levels and in the ratio of cholesterol to total sterols was noted in all patients. The most marked improvement was noted in patients presenting with initial cholesterol levels < 40 mg/dl. No toxicity was observed. Clinical improvement in growth and neurodevelopmental status was also observed.

Abnormal cholesterol biosynthesis in the Smith-Lemli-Opitz syndrome.

The Smith-Lemli-Opitz syndrome is caused by an inherited defect in 7-dehydrocholesterol-delta7-reductase, the enzyme that catalyzes the last reaction in cholesterol biosynthesis, the conversion of 7-dehydrocholesterol to cholesterol. As a result, deficient cholesterol is produced and the precursor 7-dehydrocholesterol and derivatives (8-dehydrocholesterol and 19-nor-5,7,9(10)-cholestatrien-3 beta-ol) accumulate. Tissues (especially brain) deprived of cholesterol, or because of the deposited sterol precursors and derivatives, develop abnormally and function poorly. Replacement with dietary cholesterol may help correct the biochemical defects and improve symptoms.

Trisomy 15 mosaicism and uniparental disomy (UPD) in a liveborn infant.

We describe a liveborn infant with uniparental disomy (UPD) with trisomy 15 mosaicism. Third trimester amniocentesis yielded a 46,XX/47,XX,+15 karyotype. Symmetrical growth retardation, distinct craniofacies, congenital heart disease, severe hypotonia and minor skeletal anomalies were noted. The infant died at 6 weeks of life. Peripheral lymphocyte chromosomes were "normal" 46,XX in 100 cells. Parental lymphocyte chromosomes were normal. Skin biopsy showed 47,XX,+15 in 80% of fibroblasts and results were equivalent in fibroblasts from autopsy lung tissue. Molecular analysis revealed maternal uniparental heterodisomy for chromosome 15 in the 46,XX cell line. We describe an emerging phenotype of trisomy 15 mosaicism, confirm that more than one tissue should be studied in all cases of suspected mosaicism, and suggest that UPD be considered in all such cases.

Abnormal cholesterol metabolism in Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome (SLOS) is a common autosomal recessive disorder. Children with SLOS present with specific facial dysmorphism and have multiple congenital anomalies including cleft palate, congenital heart disease, genitourinary anomalies, and limb abnormalities. They also manifest severe failure to thrive and mental retardation. A metabolic defect at the final step in the cholesterol biosynthetic pathway has been described in SLOS patients. This defect results in markedly reduced cholesterol levels and abnormal accumulation of cholesterol precursors, particularly 7-dehydrocholesterol. This newly described metabolic defect in humans is one of only a few metabolic errors known to cause multiple birth defects. The biochemical profile of reduced plasma cholesterol levels in association with markedly elevated levels of the cholesterol precursor 7-dehydrocholesterol is now used to confirm the diagnosis of SLOS, which was formerly made on purely clinical grounds. This biochemical abnormality has been confirmed in dozens of patients with SLOS in both the United States and Europe. The severe cholesterol deficiency seen in these patients has multiple effects on health and early childhood development, because cholesterol is an essential component of many cell functions, which explains many of the clinical findings seen in SLOS.

Abnormal cholesterol biosynthesis in the Smith-Lemli-Opitz syndrome.

We measured plasma sterol concentrations in 7 homozygotes with the Smith-Lemli-Opitz syndrome, 5 heterozygotes and rats treated with BM 15.766, the competitive inhibitor of 7-dehydrocholesterol 7-reductase. Low cholesterol associated with markedly elevated 7-dehydrocholesterol concentrations were detected in the plasma of all homozygotes and inhibitor-treated rats. Heterozygotes were clinically normal and, like control subjects, showed only trace amounts of 7-dehydrocholesterol in plasma. We conclude that the Smith-Lemli-Opitz syndrome is due to an inherited defect in 7 dehydrocholesterol 7-reductase which causes the accumulation of 7-dehydrocholesterol and a deficiency of cholesterol in the plasma, a biochemical abnormality that can be reproduced in rats treated with BM 15.766.

Physical findings in 21q22 deletion suggest critical region for 21q- phenotype in q22.

Multiple abnormalities were observed in a newborn infant with a deletion in the long arm of chromosome 21, from band 22q22.1-->qter. The phenotype of this infant was similar to that previously described in infants with deletions spanning the long arm of chromosome 21, from the centromere to 21q22 [Rethoré et al., 1972, Exp Cell Res 70:455-456, 1973, Ann Genet (Paris) 16:271-275]. However, as a phenotypically normal child with normal intelligence and with deletion of 21q11.1-21q21.3 has also been identified [Korenberg et al., 1991, Hum Genet 87:112-118], this case suggests that the critical region of deletion for the 21q- phenotype lies distal to 21q21, within 21q22.1-22.2.

Markedly inhibited 7-dehydrocholesterol-delta 7-reductase activity in liver microsomes from Smith-Lemli-Opitz homozygotes.

We investigated the enzyme defect in late cholesterol biosynthesis in the Smith-Lemli-Opitz syndrome, a recessively inherited developmental disorder characterized by facial dysmorphism, mental retardation, and multiple organ congenital anomalies. Reduced plasma and tissue cholesterol with increased 7-dehydrocholesterol concentrations are biochemical features diagnostic of the inherited enzyme defect. Using isotope incorporation assays, we measured the transformation of the precursors, [3 alpha- 3H]lathosterol and [1,2-3H]7-dehydrocholesterol into cholesterol by liver microsomes from seven controls and four Smith-Lemli-Opitz homozygous subjects. The introduction of the double bond in lathosterol at C-5[6] to form 7-dehydrocholesterol that is catalyzed by lathosterol-5-dehydrogenase was equally rapid in controls and homozygotes liver microsomes (120 +/- 8 vs 100 +/- 7 pmol/mg protein per min, P = NS). In distinction, the reduction of the double bond at C-7 [8] in 7-dehydrocholesterol to yield cholesterol catalyzed by 7-dehydrocholesterol-delta 7-reductase was nine times greater in controls than homozygotes microsomes (365 +/- 23 vs 40 +/- 4 pmol/mg protein per min, P < 0.0001). These results demonstrate that the pathway of lathosterol to cholesterol in human liver includes 7-dehydrocholesterol as a key intermediate. In Smith-Lemli-Opitz homozygotes, the transformation of 7-dehydrocholesterol to cholesterol by hepatic microsomes was blocked although 7-dehydrocholesterol was produced abundantly from lathosterol. Thus, lathosterol 5-dehydrogenase is equally active which indicates that homozygotes liver microsomes are viable. Accordingly, microsomal 7-dehydrocholesterol-delta 7-reductase is inherited abnormally in Smith-Lemli-Opitz homozygotes.

Correlation of severity and outcome with plasma sterol levels in variants of the Smith-Lemli-Opitz syndrome.

OBJECTIVES: To determine whether type I and the more severe type II variant of Smith-Lemli-Opitz syndrome have the same metabolic defect and to learn which plasma sterol measurements best predict survival. METHODS: Plasma sterols were measured in 33 individuals (24 type I, 9 type II) with a clinical diagnosis of the syndrome. RESULTS: Cholesterol levels were abnormally low (61 +/- 34 mg/dl) in type I subjects, whereas concentrations of the cholesterol precursor 7-dehydrocholesterol and its isomer 8-dehydrocholesterol were elevated 40- to 10,000-fold. Plasma cholesterol levels were significantly lower and total dehydrocholesterol levels higher in type II than in type I. Six children with the type II variant died by 13 weeks with mean plasma cholesterol levels 6.2 +/- 3.1 mg/dl, versus 17 +/- 11 mg/dl in the three surviving children with type II (p < 0.05). No child with a cholesterol level 7 mg/dl or less lived longer than 13 weeks. CONCLUSIONS: Patients with type I and type II variants of Smith-Lemli-Opitz syndrome have markedly reduced activity of the enzyme that converts 7-dehydrocholesterol to cholesterol, but the extent of the block is far more complete in type II. Survival correlates strongly with higher plasma cholesterol concentrations.