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American Journal of Medical Genetics 68:305–310 (1997)
© 1997 Wiley-Liss, Inc.
Clinical Effects of Cholesterol Supplementation in
Six Patients With the Smith–Lemli–Opitz Syndrome
(SLOS)
Ellen R. Elias,1* Mira B. Irons,1Anne D. Hurley,2G. Stephen Tint,3and Gerald Salen3
1 Division of Clinical Genetics, Department of Pediatrics, Tufts-New England Medical Center, Boston, Massachusetts
2 Department of Psychiatry, Tufts-New England Medical Center, Boston, Massachusetts
3 Research Service, VA Medical Center, E. Orange, New Jersey
We describe the clinical effects of choles-
terol 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 ther-
apy were seen in all patients, irrespective of
age at onset of treatment, or severity of cho-
lesterol defect. Effects of treatment in-
cluded improved growth, more rapid devel-
opmental progress, and a lessening of
problem behaviors. Pubertal progression in
older patients, a better tolerance of infec-
tion, improvement of gastrointestinal symp-
toms, and a diminution in photosensitivity
and skin rashes were also noted. There were
no adverse reactions to treatment with cho-
lesterol. This preliminary study suggests
that cholesterol supplementation may be of
benefit to patients with the SLOS. Am. J.
Med. Genet. 68:305–310, 1997.
© 1997 Wiley-Liss, Inc.
KEY WORDS: cholesterol therapy; 7-de-
hydrocholesterol (7-DHC);
Smith–Lemli–Opitz syndrome
(SLOS)
INTRODUCTION
In 1993, a defect in cholesterol biosynthesis was first
reported in Smith–Lemli–Opitz syndrome [Irons et al.,
1993]. This defect in the enzyme 7-dehydrocholesterol-
D7-reductase results in markedly deficient plasma and
tissue cholesterol levels, and accumulation of the cho-
lesterol precursor, 7-dehydrocholesterol (7-DHC) [Tint
et al., 1994]. Because cholesterol is an essential compo-
nent of cell membranes and central nervous system
myelin, and is the substrate for many biological com-
pounds including bile acids and adrenal hormones, its
deficiency has important biophysiological conse-
quences. Many of the medical problems associated with
SLOS, including severe growth failure, CNS dysgene-
sis, delayed myelinization, and ambiguous genitalia,
can now be explained by the cholesterol deficiency,
while problems such as hypersensitive skin and
cataract formation probably result from the deposition
of 7-DHC, or the substitution of 7-DHC in place of cho-
lesterol [Irons et al., 1995a].
This paper summarizes our experience in developing
a treatment protocol for SLOS patients, particularly
the clinical effects of therapy in the 6 patients we have
followed for up to 2 years. Because the cholesterol
biosynthetic defect associated with SLOS causes anom-
alies of prenatal onset, and treatment was not started
until late childhood in several of the patients, we did
not expect to see many substantial effects of therapy.
However, we have noted clinical consequences of ther-
apy, even in older patients, and many of the changes
seem beneficial.
EARLY THERAPEUTIC TRIALS
Since the initial description of the biochemical defect,
we have been treating SLOS patients on an experimen-
tal research protocol, consisting of cholesterol replace-
ment. The purpose of this treatment was to try to cor-
rect the biochemical defect found in SLOS patients, but
also to help ameliorate some of the medical problems
plaguing these children. The first attempts at therapy
involved using high cholesterol foods, but were limited
by severe gastrointestinal tract dysmotility and food al-
lergies to egg and milk. However, improvement in
plasma cholesterol levels was noted, as were some clin-
ical effects including weight gain, a decrease in irri-
tability, and improved muscle tone [Irons et al., 1994].
Because of severe feeding intolerance, one patient
had been fed a special formula (“LOG”) from age 6
months to 3 years. This formula, based on lamb’s meat,
Contract grant sponor: Clinical Research Study Unit at New
England Medical Center.
*Correspondence to: Ellen R. Elias, M.D., Children’s Hospital,
Fegan 10, 300 Longwood Ave, Boston, MA 02115.
Received 22 April 1996; Accepted 11 June 1996
contains 6–7 times the amount of cholesterol found in
regular infant formulas. This child showed normal
growth parameters for age while on the lamb-based for-
mula. Her growth rate declined when changed to a
more traditional low-cholesterol formula, and then in-
creased again when begun on cholesterol supplementa-
tion at age 4 years (Fig. 1). LOG formula is an alterna-
tive therapy for infants with SLOS, and has led to
improved growth and nutrition in at least one other
SLOS patient (Nwokoro, personal communication). Its
use is hampered by an unpleasant appearance and
aroma, and difficulty in its preparation.
The early therapeutic attempts suggested that treat-
ment with cholesterol and bile acids could alter the ab-
normalities in sterol and bile acid levels seen in SLOS,
and could lead to some clinical improvement. However,
GI tract dysfunction and food allergy limited the effec-
tiveness of this trial. This prompted the development of
a pure cholesterol medication for use in patients with
SLOS.
TREATMENT PROTOCOL (JANUARY
1994–PRESENT)
Six patients with clinically suspected and biochemi-
cally confirmed SLOS were started on an experimental
treatment protocol approved by the New England Med-
ical Center Human Investigation Review Board, after
obtaining informed consent from the parents. The pa-
tient group consisted of 4 girls, ranging in age from
birth to 11 years at onset of therapy, and 2 boys, age 2
and 8 years at onset (Table I). Patients 2 and 3 are sec-
ond cousins and patients 5 and 6 are sibs.
Since January 1994, an FDA-approved pure choles-
terol suspension has been used. In the first 4 patients
the cholesterol was initially used in combination with
two bile acids given to enhance cholesterol absorption,
ursodeoxycholic acid (Actigall®), and chenodeoxycholic
acid (Chenix®). In addition to facilitating cholesterol
absorption, Chenix®also suppresses the rate-control-
ling enzyme of cholesterol biosynthesis (3-hydroxy-3-
methylglutaryl CoA or HMG CoA reductase), and it
was hoped that its use would lead to a decrease in 7-
DHC biosynthesis.
The suspension of pure cholesterol dissolved in soy-
bean oil (200 mg/ml) was administered either orally or
per gastrostomy tube and was well tolerated without
side effects. The pure cholesterol was initially adminis-
tered at a dose of 40–60 mg/kg/day, and gradually in-
creased to the current dose of 100–125 mg/kg/day. Acti-
gall®, given at a dose of 15 mg/kg/day, is a bile acid
which has been used extensively in pediatric patients
with liver diseases, and was also well tolerated.
Chenix®, used at a dose of 7 mg/kg/day, was associated
with some mild GI side effects in two patients.
All patients showed increases in plasma cholesterol
on therapy and in the percent of total sterols consisting
of cholesterol. The combination of cholesterol plus the
two bile acids Actigall®and Chenix®seemed to be more
effective then cholesterol plus Actigall alone in raising
serum cholesterol levels. Unfortunately, late in 1994,
the Chenix®became unavailable, due to manufacturing
issues. The patients were then continued on cholesterol
plus Actigall®alone. The cholesterol levels started to
drop in two patients on this regimen, and information
became available that Actigall®may actually decrease
cholesterol absorption from the GI tract [Wang et al.,
1995]. The Actigall®was then discontinued, and since
1995, patients have been treated with cholesterol alone
[M. Irons et al., presented at NIH-sponsored SLOS con-
ference, Bethesda, 9/95].
METHODS
To study the clinical consequences of cholesterol and
bile acid therapy the patients were evaluated at
306 Elias et al.
Fig. 1. Growth parameters of patient 3. These graphs illustrate that growth velocity was normal in
this SLOS patient while receiving a high-cholesterol diet between age 6 months and 3 years, slowed on
regular (low cholesterol) formula between age of 3 and 4 years, and then improved again once the cho-
lesterol suspension was begun (horizontal arrow denotes high-cholesterol lamb-based formula, vertical
arrow denotes cholesterol and bile acid therapy).
monthly clinic visits. Interval history and physical ex-
amination were documented to assess effects of therapy
on development, behavior, pubertal status, skin find-
ings, cataracts, intercurrent illness, and GI symptoms.
Table II lists the clinical and laboratory parameters
which were evaluated during this study.
RESULTS
Evidence of clinical benefits of therapy have been
seen, even in older patients. None of the patients de-
veloped side effects from the cholesterol suspension.
Growth and Nutrition
Patients have shown improved rates of growth on the
cholesterol supplementation. An acceleration in
weight, height, and head circumference was noted,
even in older patients. For example, the head circum-
ference of Pt. 2 was 48 cm from age 6 years to age 11
years, grew 1 cm in the first 4 months of therapy, and 2
cm since starting therapy. Serum levels of fat-soluble
vitamins were measured and were normal in all pa-
tients tested [Irons et al., 1995b]. Lipoprotein levels
have been added to the protocol only recently.
Neuropsychological Course
Behavior changes on therapy occurred fairly rapidly,
within days to weeks of starting therapy. Parents,
teachers, and clinicians noted a decrease in irritability,
hyperactivity, and self-injurious behaviors, and an in-
creased attention span. Improvement in muscle tone
has occurred, but following a lag time of about 6 months
on therapy. Improved rate of developmental progress
was seen, also with a lag time of about 6 months fol-
lowing the onset of cholesterol. For example, Pt. 2 was
wheelchair-bound before therapy, and is now able to
walk with a walker, and Pt. 3, formerly in a wheelchair,
is now walking independently and running.
Improvement in language and cognitive skills has
also been noted, particularly as decreased irritability
and improved attention span allow for a more beneficial
outcome from early intervention and school programs.
Pt. 2, nonverbal for the first 11 years of her life, can now
indicate “yes” and “no,” and make choices with a com-
puter switch. Pt. 3, also nonverbal at the onset of ther-
apy, now consistently uses 30 signs to communicate.
Of particular interest is a sib pair; the older brother,
Pt. 5, started cholesterol therapy at age 2 years, and
Cholesterol Treatment of SLOS 307
TABLE I. Patients on SLOS Therapy
Plasma cholesterol
Pt. Sex Ageamg/dla
1 F 23 mo 8
2 F 11 yr 20
3 F 4 yr 62
4 M 8 yr 44
5 M 2 yr 33
6 F Birth 29
aPre-treatment.
TABLE II. Variables to Be Monitored on Therapy
Source Test Frequency of testing
Blood Cholesterol Monthly (q 3 mo once stable)
7-DHC Monthly (q 3 mo once stable)
CBC, platelets Every 3 months
SGOT/SGPT Every 3 months
BUN/Creatinine Every 3 months
Cortisol Yearly (if abnl initially)
Sex hormonesaYearly
Fat-soluble vitamins Yearly (if abnl initially)
Lipoproteins Yearly
Urine Bile acids Every 6 months
Stool Bile acids Every 6 months
Clinical Wt, ht, OFC Every month
Interval history Every month
Infection
Rashes
GI
Psychomotor development
Cataracts Every 6 months
Head MRI At entry and every 2 years
IQ/behavior Yearly (formal testing)b
aTestosterone in males, estradiol in females.
bThe patients were evaluated by a licensed clinical psychologist at New England
Medical Center (ADH), who performed formal neuropsychological testing to deter-
mine the child’s developmental/intellectual quotient (DQ/IQ). This testing utilized
the Bayley Scale of Infant Development, the Vineland Adaptive Behavior Scale,
the Stanford-Binet Intelligence Scale 4th edition, the Stanford-Binet Intelligence
Scale LM, the Peabody Picture Vocabulary Test—Revised, and the McCarthy
Scales of Children’s Abilities, as appropriate. These tests are well standardized
and reproducible neuropsychological tests. In older patients, rate of developmen-
tal progress is compared to that seen before therapy. Behavior was scored objec-
tively using the Aberrant Behavior Checklist, and the Reiss Scales for Children’s
Dual Diagnosis. These neuropsychological tests are designed to assess behavior
problems in children with mental retardation and are standardized tests.
the younger sister, Pt. 6, at birth. The parents feel, and
formal testing confirms, that the younger sib is showing
a faster rate of development than the brother, although
both had comparable pretreatment cholesterol levels
(Fig. 2).
Endocrine Function
Cortisol levels were normal in all patients. Results
of adrenal stimulation testing, performed in Pts. 1, 2,
and 4, have also been normal. Of interest is that rapid
pubertal advancement was noted in the 2 older pa-
tients once cholesterol was available as a substrate for
sex hormone production. Pt. 2 advanced from Tanner
I to Tanner III over a 6-month period (physical changes
which normally occur over a 2-year period), once
started on cholesterol. Pt. 4 has developed pubic hair,
but no further pubertal changes have occurred so far.
Dermatological Problems
Severe photosensitivity improved significantly in
Pts. 2, 3, and 4, for whom it was a problem pretreat-
308 Elias et al.
Fig. 2. Pt 5 began cholesterol therapy at age 2 years. His sister, Pt.
6, began cholesterol at birth. She is achieving developmental mile-
stones at a faster rate than her brother (A–C).
ment. Improvement in skin rashes was seen in these
same patients.
Ophthalmological Problems
Two of the 6 patients had cataracts. A cataract from
Pt. 1 was extracted and proved to be composed of 7-
DHC, demonstrating that the enzyme defect in SLOS
causes storage disease-like manifestations. The
cataract of Pt. 4 is stable, during the 4 years before on-
set of therapy, and in the 2 years since therapy began.
Infectious Diseases
There appears to be a diminution in the number and
severity of intercurrent infections while on therapy.
Prior to therapy, multiple ear infections necessitating
placement of PE tubes, and frequent pneumonias, some
requiring hospitalization, were seen in Pts. 1–4. Since
the institution of cholesterol therapy, the number of
courses of antibiotics prescribed, the number of hospi-
talizations required, and the clinical severity of inter-
current illnesses all are diminished. For example, prior
to treatment, Pt. 2 had 4–6 episodes of otitis per year,
necessitating placement of PE tubes several times. She
required 2 hospitalizations for pneumonia, and one for
staphylococcal sepsis. Since being on cholesterol ther-
apy, she has only had 5 bouts of otitis over a 2-year pe-
riod, and no hospitalizations for infection. Pt. 3 had dif-
ficulty handling upper respiratory infection and
required hospitalization at age 2 for meningitis. She
had 2–5 episodes of otitis per year, resulting in conduc-
tive hearing loss by age 2, but on therapy has been in-
fection-free since April 1995 and now has normal hear-
ing. Hearing loss also improved in Pt. 1, perhaps
secondary to reduced episodes of otitis.
Gastrointestinal Problems
Gastrointestinal problems including tolerance of G
tube feeding, dysmotility with severe constipation, and
recurrent GI bleeds are clinically improved on therapy
in Pts. 1–4. Pts. 5 and 6 are able to tolerate oral feed-
ings, and did not have as severe GI symptoms pre-
treatment.
DISCUSSION
We report preliminary observations of a treatment
protocol which has been evolving over time. The study
patients are difficult to compare because they are few in
number, have different degrees of severity of their bio-
chemical defects, and were started on treatment at dif-
ferent ages. If the older patients are used as their own
controls (i.e., when the clinical course is compared pre-
and posttreatment), a number of clinical characteris-
tics seem to be affected by therapy.
The children show a more rapid growth rate on cho-
lesterol, including growth in head circumference. This
is despite the fact that cholesterol given enterally is not
thought to cross the blood–brain barrier. It is possible
that the blood–brain barrier may be more permeable to
cholesterol in the face of severe cholesterol deficiency.
Reduced photosensitivity and incidence of skin rashes
were noted on treatment, the mechanism of which is
unclear, but may relate to abnormal skin cell mem-
branes caused by deficient cholesterol and 7-DHC accu-
mulation in the epidermis. The improvement in GI
symptoms and tolerance of infection seen may be sec-
ondary to improved nutritional status. Fat-soluble vit-
amins were normal in all patients tested, suggesting
that vitamin deficiency does not cause clinical symp-
toms in SLOS patients.
None of the patients had symptomatic heart or renal
disease. Pt. 2 had successful surgical repair of an
asymptomatic atrial septal defect in 1995. Although
the cardiovascular team had initially elected not to op-
erate, this decision was reversed based on the team’s
perception of significant clinical improvement in this
patient on the cholesterol therapy.
Developmentally, a more rapid rate of progress has
surprised teachers and therapists, as well as parents.
The 11-year-old girl who learned to walk with a walker
and manipulate switches, and her 4-year-old cousin
who learned to walk independently and use 30 signs
since therapy have commenced, are 2 examples of such
progress. Without blinded placebo testing, it is difficult
to prove that these changes are in fact the result of
therapy, and might not have occurred otherwise. How-
ever, these children have been followed by the same
clinician, teachers, and therapists for many years both
pre- and posttreatment, and the same improvement
has been noted by all, even by those educational pro-
fessionals unaware that the child was on a research
protocol.
Behavior changes have been interesting to observe,
as they appear to occur fairly rapidly after starting cho-
lesterol therapy. The most obvious change is a decrease
in irritability, and an increase in alertness. A decrease
in self-injurious behaviors is also noted. Again, these
changes were observed by therapists unaware of the
onset of cholesterol treatment, as well as by parents
and many different clinicians involved in the childrens’
care. The rapidity with which these behavior changes
are manifested has suggested a possible “sterol ef-
fect”—i.e., cholesterol is now available as a substrate
for sterol production, which then affects behavior,
rather than the changes being an effect of the choles-
terol on central nervous system structure.
Pubertal changes were rapid in 2 older patients and
are easily explained by the cholesterol now being avail-
able to serve as substrate for sex hormone production.
Improved nutrition may also play a role in the pubertal
advancement.
Although these preliminary observations are gratify-
ing, a great deal of work remains to be done before the
cholesterol defect in SLOS is fully understood, and it
can be proven that cholesterol therapy is truly benefi-
cial in this disease. Continued study of these patients
over time, and study of a larger cohort of patients will
be necessary, so that children of comparable age and de-
gree of biochemical defect can be identified, and mean-
ingful statistical analysis accomplished. Because the
effects of the cholesterol deficiency begin prenatally,
treatment, even if started immediately after birth as in
Pt. 6, is unlikely to result in a normal outcome. Animal
studies in pregnant rats fed an inhibitor of the enzyme
defective in SLOS, and supplemented with cholesterol,
suggest that there may be some benefit to prenatal
Cholesterol Treatment of SLOS 309
therapy [Barbu et al., 1988]. This possibility is an area
for future research.
Better understanding of cholesterol absorption
through the GI tract, and its passage across the
blood–brain barrier, will be important in helping to de-
sign more effective treatment strategies. A greater un-
derstanding of the enzyme defect may allow more spe-
cific and appropriate treatment to be designed for the
different levels of severity seen in SLOS. Whether bile
acids in addition to cholesterol are helpful, and which
bile acids are most effective, are further questions
which collaboration with ongoing laboratory research
efforts [Xu et al., 1995] will help to answer. The roles of
lipoproteins and lipoprotein receptors in SLOS is an-
other area for future study.
In conclusion, SLOS patients treated with choles-
terol have shown improvement in rate of growth, be-
havior, rate of developmental progress, and in derma-
tologic, gastrointestinal and infectious disease, which
suggest that treatment with cholesterol has a beneficial
effect. No patient has experienced any harmful conse-
quences of treatment. Further study is ongoing to at-
tempt to develop an effective treatment protocol for
SLOS patients. It is hoped that these preliminary ob-
servations of cholesterol therapy in SLOS will lead to a
greater understanding of the biochemistry involved,
but more importantly, will lead to an improved quality
of life for these patients and their families.
ACKNOWLEDGMENTS
We thank Ross Laboratories for their generous gifts,
which have enabled us to purchase cholesterol, and the
Clinical Research Study Unit at New England Medical
Center, which has supported this study since the Fall of
1994.
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