Identification of risk factors for autism
spectrum disorders in tuberous
A.L. Numis, MD
P. Major, MD
M.A. Montenegro, MD,
D.A. Muzykewicz, BS
M.B. Pulsifer, PhD
E.A. Thiele, MD, PhD
Objective: The purpose of this study was to assess the prevalence of and to identify epidemio-
logic, genetic, electrophysiologic, and neuroanatomic risk factors for autism spectrum disorders
(ASD) in a cohort of patients with tuberous sclerosis complex (TSC).
Methods: A total of 103 patients with TSC were evaluated for ASD. A retrospective review of
patients’ records was performed, including mutational analysis. EEG reports were analyzed for
the presence of ictal and interictal epileptiform features. Brain MRI scans were evaluated for TSC
neuropathology, including tuber burden.
Results: Of the 103 patients with TSC, 40% were diagnosed with an ASD. On univariate analysis,
patients with ASD were less likely to have mutations in the TSC1 gene. Patients with ASD also
had an earlier age at seizure onset and more frequent seizures. On EEG, those with ASD had a
significantly greater amount of interictal epileptiform features in the left temporal lobe only. On
MRI, there were no differences in the regional distribution of tuber burden, although those with
TSC2 and ASD had a higher prevalence of cyst-like tubers.
Conclusions: The development of ASD in TSC is not well understood. Given our findings, ASD may
be associated with persistent seizure activity early in development in particular brain regions,
such as those responsible for social perception and communication in the left temporal lobe. The
presence of cyst-like tubers on MRI could provide a structural basis or marker for ASD pathology
in TSC, although studies assessing their effect on cortical function are needed. Neurology®2011;
ASD ? autism spectrum disorders; DSM-IV ? Diagnostic and Statistical Manual of Mental Disorders, 4th edition; FLAIR ?
fluid attenuation inversion recovery; GAP ? guanosine triphosphatase-activating protein; NMI ? no mutation identified; NP ?
neurophysiologic; SEN ? subependymal nodule; TSC ? tuberous sclerosis complex.
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder resulting from muta-
tions in the TSC1 or the TSC2 gene.1,2Neurologic involvement occurs in more than 90% of
individuals and comprises several distinct lesions.3Seizure disorders are present in 70%–90%
of patients and often develop within the first year of life.4Developmental and behavioral
disorders, including autism spectrum disorders (ASD), are also frequently diagnosed in TSC.
ASD are characterized by impaired social interaction, restricted interests, and repetitive
behaviors. ASD affects between 17% and 63% of patients with TSC, a prevalence dramatically
higher than that of the general population.5,6Studies suggest that mental retardation and early
onset of epilepsy in TSC, in particular infantile spasms, are associated with the development of
ASD in this group.7,8In addition, there is evidence of an association between temporal lobe
epileptiform foci with ASD in TSC.9However, investigations seeking to implicate TSC genet-
ics10–12or neuropathology13–19in ASD have yielded inconclusive results. Discrepancies between
investigations may result, in part, from varying methods used to diagnose ASD. To date, no
From the Department of Neurology (A.L.N., P.M., D.A.M., E.A.T.) and Psychological Assessment Center (M.A.P.), Massachusetts General Hospital,
Study funding: Supported by the Carol and James Herscot Center for Tuberous Sclerosis Complex, NIH 5P01NS024279, and the Doris Duke
Charitable Foundation (A.L.N.).
Disclosure: Author disclosures are provided at the end of the article.
Address correspondence and
reprint requests to Dr. Elizabeth
A. Thiele, Carol and James
Herscot Center for Tuberous
Sclerosis Complex, 175
Cambridge Street, Suite 340,
Boston, MA 02114
Copyright © 2011 by AAN Enterprises, Inc.
aspect of brain pathology in TSC has been
shown to be necessary and sufficient for the
development of ASD.
The present study investigates the relation-
ship between ASD and TSC in an attempt to
identify genetic, electrophysiologic, and neu-
roanatomic risk factors. To control for vari-
ability in the diagnostic criteria of ASD, the
cohort was evaluated by a single neuropsy-
chologist using standardized and validated
measures. Our cohort size was selected to al-
low for appropriately powered analyses of ge-
netic, clinical history, and electrophysiologic
METHODS Participants. We reviewed the clinical records
of patients meeting the published clinical diagnostic criteria for
TSC followed at the Herscot Center for Tuberous Sclerosis
Complex at Massachusetts General Hospital.3A total of 103
patients with ages ranging from 3 to 55 years had undergone
comprehensive neuropsychologic (NP) testing with a single neu-
ropsychologist from 2002 to 2009. NP testing included a stan-
dard battery to measure intelligence and adaptive functioning.
The diagnosis of an ASD was based on DSM-IV criteria, using a
clinical interview and completion of standardized questionnaires
including the Child Symptom Inventory–4 Parent Checklist,
Behavioral Assessment System for Children–2, and Gilliam
Asperger’s Disorder Scale.20–22On review of patients’ neurologic
records, mean seizure frequency at the time of NP evaluation
and maximum seizure frequency were coded as nonparametric
variables as follows: 0, none; 1, fewer than one per month; 2, at
least one per month; 3, at least one per week; and 4, daily.
Standard protocol approvals, registrations, and patient
consents. We received approval from the institutional review
board of the Massachusetts General Hospital.
TSC mutational analysis. All patients were offered genetic
testing as part of their comprehensive evaluation, including mu-
tational analysis of the TSC1 and TSC2 genes and detection for
large DNA deletions and rearrangements of the TSC2 gene.
Testing was performed at Athena Diagnostics (Worcester, MA)
or the Massachusetts General Hospital Neurogenetic Diagnostic
Laboratory (Boston, MA). Patients in whom genetic testing re-
sults were negative are classified herein as no mutation identified
EEG. EEG records were analyzed for patients who had under-
gone at least 25 minutes of surface monitoring with a 10–20
system of electrode placement. In all cases, patients had been
referred for EEG to further characterize and assess their seizure
disorder. EEG reports were included in analysis only if wave
amplitude and frequency were reported. When more than one
EEG record was available, the EEG record closest in date to the
last NP examination was analyzed. The EEG field was divided
into lobes as follows: frontal, Fp1–2 and F3–4; temporal, F7–8
and T3–4; parietal, C3–4 and P3–4; and occipital, T5–6 and
O1–2. The EEG record was assessed for the presence of ictal
activity, slowing, and regional epileptiform features including
spikes, sharp waves, and spikes and waves. When epileptiform
discharges were reported as broadly distributed, spatial analysis
of amplitudes was used to help in further localization.
MRI. All patients were referred for brain MRI at the time of
diagnosis with TSC, annually to screen for growth of subependy-
mal nodules (SENs) to subependymal giant cell tumors, or as
symptoms necessitated. MRI was performed on a 1.5- or 3.0-
Tesla system (GE Signa, Madison, WI). Sequence details can be
found in appendix e-1 on the Neurology®Web site at www.
neurology.org. MRI scans acquired closest in time to the formal
NP assessment were retrospectively reviewed by 2 study investi-
gators (A.L.N. and P.M.) after consultation with a pediatric neu-
roradiologist. In patients who had a history of resective epilepsy
surgery, preoperative imaging was used for analysis. Each cere-
Table 1Characteristics of genetics, epilepsy, and MRI features in TSC
TSC with ASD TSC without ASDp Value
Genetic testing, n (%)
3 (8)21 (38)0.002
27 (75)31 (55)0.077
No mutation identified
6 (17) 4 (7)NS
Epilepsy, n (%)
40 (98) 51 (82)0.025
Intractable epilepsy, n (%)a
28 (68)32 (52)NS
Infantile spasms, n (%)
24 (59)20 (32)0.014
Age at seizure onset, y, mean ? SD
0.7 ? 0.6 2.9 ? 4.2 0.002
Prior AED, n, mean ? SDb
4.4 ? 2.53.5 ? 3.30.025
Epilepsy surgery, n (%)
12 (29) 6 (10)0.016
Ketogenic diet or LGIT, n (%)
4 (10) 6 (10)NS
Ictal activity, n (%)
6 (15)10 (16)NS
Generalized slowing, n (%)
11 (32) 14 (30)NS
Focal slowing, n (%)
17 (50)19 (41)NS
Interictal epileptiform activity, n (%)
28 (82) 28 (61)0.049
Interictal activity score, mean ? SDc
2.7 ? 2.1 1.7 ? 1.8 0.039
MRI characteristics, n (%)
6 (18) 12 (23)NS
20 (59)16 (30) 0.015
Cortical tubers with calcification
10 (29)15 (28)NS
White matter changesd
14 (41)22 (41)NS
34 (100)51 (96)NS
Abbreviations: AED ? antiepileptic drug; ASD ? autism spectrum disorders; LGIT ? low
glycemic index treatment; NS ? not significant; SEN ? subependymal nodule; TSC ? tuber-
ous sclerosis complex.
aDefined as ?3 AEDs (nonbenzodiazepine) without total cessation of seizure activity.
bExcluding as-needed Valium and Ativan.
cNumber of brain lobes (left and right frontal, temporal, parietal, and occipital) with interic-
tal epileptiform features.
d?3 radial glial bands.
Neurology 76 March 15, 2011
bral lobe was evaluated for the presence of cortical tubers, cyst-
like tubers (figure e-1, A and B), and cortical tubers with
calcifications (figure e-1, C and D).15,23,24Tubers demonstrating
central or peripheral fluid-attenuation inversion recovery
(FLAIR) suppression and concomitant increases in fast spin-
echo T2 signal intensity were classified as cyst-like. Tubers with
regions containing concomitant suppression of FLAIR and T2
signal intensity were classified as tubers with calcification. All
lesions identified were verified on at least 2 sequences. The corti-
cal region with the largest cortical tuber burden (by volume) and
the cortical region with the largest sized cortical tuber were re-
corded. Cerebellar tubers, white matter radial glial bands, and
number of SENs were noted. Discordant findings between the
evaluators were resolved by consensus.
Statistical analysis. Statistical analyses were performed using
SPSS version 15.0 (SPSS, Inc., Chicago, IL). Individuals with
TSC and ASD were considered case patients, and patients with
TSC and without ASD were considered control patients. Con-
tinuous variables were analyzed by a 2-sample t test and are pre-
sented as means ? SE. Categorical variables were assessed by the
Fisher exact test or ?2test. Nonparametric variables were as-
sessed by the Mann-Whitney U test. The Spearman rank order
correlation was used to assess the relationship between cyst-like
tubers and age. Forced entry binary logistic regression was per-
formed to assess the impact of a number of factors on the likeli-
hood of having ASD in our cohort. The exponentiation of the B
coefficient values were used to determine odds ratios. All re-
ported p values used 2-tailed tests of significance with ? set at
RESULTS Sample characteristics. Of 103 patients
ASD. Patients with TSC and ASD (TSC/ASD) were
younger than those without ASD (9.9 ? 4.5 vs 16.2 ?
10.2 years, p ? 0.001). Patients with TSC/ASD also
had lower IQs than those without ASD (51 ? 28 vs
81 ? 30, p ? 0.001). There was no significant differ-
ence in male gender between those with TSC/ASD
(49%) and those without ASD (42%). Those with
TSC/ASD did not differ significantly from those with-
out ASD with regard to dermatologic, renal, cardiac,
pulmonary, or ophthalmologic manifestations of TSC
Genetic analysis. Genetic analyses of the TSC1 and
TSC2 genes were available for 92 (89%) patients in
this cohort. There was a difference in mutation type
(TSC1, TSC2, or NMI) among patients with TSC/
ASD and without ASD (main effect p ? 0.006) (ta-
ble 1); on subgroup analysis, patients with TSC/ASD
had fewer TSC1 mutations (p ? 0.002). There was
no significant difference between the groups regard-
ing the mutation type (missense, nonsense/frame-
shift, splice site, or deletion). Patients with TSC/
ASD had more disease-causing mutations inactivating
the hamartin interaction domain of the TSC2 gene
than patients without ASD (28% vs 5%; p ? 0.004)
(figure e-2). There was no significant difference be-
tween the groups when the guanosine triphosphatase-
activating protein (GAP) domain of TSC2 was
examined, with 21 (58%) patients with TSC/ASD
and 24 (43%) patients without ASD having loss of
Seizure history. Several significant relationships be-
tween seizure history and ASD were found on analy-
sis (table 1). Patients with TSC/ASD had an earlier
age at seizure onset than those without ASD, which
remained true when correcting for the increased pres-
ence of infantile spasms in patients with ASD (p ?
0.002). At the time of NP evaluation, patients with
ASD had a greater mean seizure frequency (2.1 ?
1.7) than those without ASD (1.4 ? 1.4; p ?
0.047). In addition, patients with ASD had a greater
prior maximum seizure frequency (3.5 ? 1.0; be-
tween once per week and daily) than those without
ASD (2.8 ? 1.6; p ? 0.034).
EEG data. EEG reports that met the inclusion criteria
for analysis were available for 80 of the 103 patients
evaluated for ASD, including 34 of 41 (83%) pa-
tients with ASD and 46 of 62 (74%) patients with-
out ASD. There was no significant difference when
the time latency of EEG acquisition to NP evalua-
Figure 1 Localization of interictal epileptiform features in tuberous sclerosis
(A, B) Results are presented as the percentage of patients with TSC with interictal epilepti-
form activity (including spikes, sharp waves, and spikes and waves) on EEG, in a given ana-
tomic brain region. *p ? 0.05. ASD ? autism spectrum disorders; F ? frontal; L ? left; O ?
occipital; P ? parietal; R ? right; T ? temporal.
Neurology 76March 15, 2011
tion between the 2 groups was compared (1.6 ? 1.9
years for TSC/ASD and 2.1 ? 3.5 years for TSC
without ASD). Nearly all EEG records had been re-
corded in both sleep and awake states in the TSC/
ASD group (94%) and the TSC without ASD group
(87%). Furthermore, the groups did not differ signif-
icantly in the number of EEG records that contained
more than 24 hours of data recordings (47% of pa-
tients with TSC/ASD and 35% of patients with TSC
Analysis of EEG reports demonstrated no difference
regarding the presence of ictal events, focal slowing,
generalized slowing, or the degree of slowing between
the groups (table 1). Those with TSC/ASD did have a
significant increase in the presence of interictal epilepti-
form features on EEG and had more brain lobes af-
1). Epileptiform features were significantly increased in
the temporal lobe of patients with TSC/ASD (figure
1A), specifically the left temporal lobe (figure 1B). No
such difference was observed between the groups when
epileptiform features in the right temporal lobe or any
other brain region were compared. There was a trend
ital lobes of patients with TSC/ASD compared with
that in patients without ASD, specifically the left occip-
MRI data. Of the 103 patients, 87 (84%) had brain
MRI data meeting the inclusion criteria. Of these 87,
34 (39%) met the criteria for diagnosis of ASD. The
average age at MRI for patients with TSC/ASD was
8.6 ? 0.8 years and for those with TSC without
ASD was 13.1 ? 1.3 years (p ? 0.004). There was
no significant difference between the groups when
the time from NP assessment to MRI was compared
(TSC/ASD 0.6 ? 0.1 year and TSC without ASD
0.7 ? 0.1 year). Of the 87 patients, 13 (15%) had
undergone resective epilepsy surgery (10 with ASD).
Six patients without preoperative imaging who met
the inclusion criteria were excluded from analyses of
the largest regional tuber burden and size.
MRI features. Cortical tubers were present on MRI in
84 of 87 (97%) patients. The 3 patients without evi-
dence of tubers did not have the diagnosis of ASD; 2
carried TSC1 gene mutations, and 1 had NMI. Cor-
tical tubers were present in all brain lobes in 72 of 87
(83%) patients evaluated. The largest sized tuber and
tuber burden were identified most frequently in the
left or right frontal lobes (41% of patients). There
was no significant difference in the regional distribu-
tion of the largest sized tuber or tuber burden among
patients with TSC/ASD and without ASD (figure
2A). However, there was a trend for patients with
ASD to have their largest tuber burden but not the
largest sized tuber in the left temporal lobe (p ? 0.09
for burden; p ? 0.29 for size) (figure 2B). Compari-
sons of additional MRI stigmata of TSC between
these groups are found in table 1.
Figure 2 Regional distribution of the largest sized cortical tuber and largest
tuber burden in patients with tuberous sclerosis complex (TSC)/
autism spectrum disorders (ASD) and without ASD
(A) Regional percentages represent the cumulative total of the left and right region cases.
(B) Largest tuber burden by brain lobe. F ? frontal; L ? left; O ? occipital; P ? parietal; R ?
right; T ? temporal.
Figure 3 Total and regional distributions of cyst-like tubers in patients with
tuberous sclerosis complex (TSC)/autism spectrum disorders
(ASD) and without ASD
Inset: Number of cyst-like tubers in patients with TSC/ASD (3.5 ? 0.4) and without ASD
(1.2 ? 0.4). Values presented are means ? SE. *p ? 0.05; **p ? 0.01. F ? frontal; O ?
occipital; P ? parietal; T ? temporal.
Neurology 76March 15, 2011
Cyst-like tubers. Cortical tubers meeting the criteria
for cyst-like tubers were present in 36 of 87 (41%)
patients. Patients with TSC/ASD were more likely to
have these lesions than patients without ASD (p ?
0.015) (table 1). Moreover, cyst-like tubers were far
more numerous in patients with TSC/ASD (3.5 ?
0.4) than in patients without ASD (1.2 ? 0.4; p ?
0.005) (figure 3, inset). The increase in cyst-like tu-
bers did not localize to a particular brain region when
patients with and without ASD were compared (fig-
ure 3). There was a correlation between a patient’s
age and the number of cyst-like tubers on MRI, with
younger patients having more lesions (r ? ?0.45;
p ? 0.001), which remained when controlling for
the diagnosis of ASD (partial coefficient ? ?0.26;
p ? 0.014). Of note, 34 of the 36 (94%) patients
with cyst-like tubers had a TSC2 gene mutation; the
remaining 2 patients (one with TSC/ASD and one
without ASD) had TSC1 gene mutations.
Logistic regression. Logistic regression was performed
with 7 independent variables, chosen from their sta-
tistical significance on univariate analysis of ASD in
TSC (table 2). Complete datasets were available for
66 of 103 (64%) patients. On analysis, the model
correctly classified 73% of cases (p ? 0.001); the
positive predictive value was 71%, and the negative
predictive value was 74%. As shown in table 2, only
2 of the variables chosen had a unique and significant
contribution: a TSC1 mutation decreased the chance
of ASD more than 41 times, and the presence of
interictal spikes in the left temporal lobe increased
the chance of ASD by more than 15 times.
DISCUSSION The rate of ASD in TSC varies
widely in published reports from 17% to 63%.6,7,11
In our cohort of patients with TSC evaluated by a
single neuropsychologist, the prevalence of ASD was
40%. We also report a lower prevalence of TSC1
mutations in those with TSC and ASD. Although we
sampled from a tertiary clinic population, our find-
ings correlate well with prior investigations examin-
ing larger groups of patients with TSC.25–27
Moreover, we feel that sampling bias has been mini-
mized by implementing a policy at our TSC clinic to
have all children and young adults with TSC un-
dergo a formal NP evaluation to better serve our
We report that TSC mutations inactivating the
hamartin domain of the TSC2 gene were associated
with ASD in TSC. Although unlikely to be a causal
relationship, mutations in these regions of the TSC
genes may markedly increase risk of ASD, and in
combination with mutations in other modifier genes
of ASD, the phenotype can be observed. Here, our
methods detected germline mutations in TSC genes
in peripheral blood. The somatic, “second-hit” mu-
tation in the remaining TSC allele may also contrib-
ute to phenotypic variability in TSC. It is possible
that the timing and cellular location of the second hit
mutation can have downstream effects on a develop-
ing brain, including learning, behavior, and epilepto-
genesis. Although the pathogenesis of some brain
lesions in TSC may not be dependent on a second-
hit mutation,28further investigations interrogating
the relationship between neurologic phenotype and
somatic mutations in TSC pathology, including cyst-
like tubers, are warranted.
Here, we found that interictal epileptiform fea-
tures in the temporal lobe are associated with ASD,
specifically, the left temporal lobe. This laterality has
not been reported previously. Interestingly, the prev-
alence of interictal epileptiform features was mark-
edly high in both groups, demonstrating the
epileptogenicity of the brain in TSC. Localization of
focal interictal epileptiform features in patients with
TSC has been demonstrated to be stable for more
than 10 years.29Thus, although the dates of our EEG
data and NP evaluations were often disparate in a
given patient, our data may still accurately depict the
electrographic nature of his or her brain at the time
of NP evaluation.
Intriguingly, we report that timing of seizure on-
set and increased seizure frequency were associated
with ASD. From this, it is plausible that early detec-
tion and treatment of both clinical seizures and epi-
leptiform features in TSC could change the course of
disease progress. Indeed, evidence from our group
and recent evidence from a small cohort in Italy sug-
gest that early and effective treatment may improve
neurodevelopmental outcomes.30,31Routine EEG in
the first years of life may provide a useful screening
technique in all patients with TSC to assess both sub-
Table 2 Variables in the logistic regression model
95% CI of ORb
?3.7 ? 1.40.007c
41.7 2.7 500
1.6 ? 1.0 0.13 45.00.638.5
Age at seizure onset
?0.08 ? 0.06 0.171.10.091.2
? Infantile spasms
?0.3 ? 0.8 0.681.4 0.36.7
? LT interictal spikes
2.7 ? 0.90.002c
15.1 2.8 82.9
? Largest tuber burden in LT lobe
1.5 ? 1.00.12 4.4 0.7 28.2
? Cystic tubers
?0.7 ? 0.8 0.411.9 0.49.1
Abbreviations: CI ? confidence interval; LT ? left temporal; OR ? odds ratio; TSC ? tuber-
ous sclerosis complex.
aThe coefficient of that variable in the overall model.
b95% CIs surrounding the OR.
cp ? 0.01.
Neurology 76March 15, 2011
clinical seizures and epileptiform features. However,
delineating the role that such abnormalities may have
on the progression of ASD in TSC will pose substan-
tial methodologic challenges.
Despite our use of the MRI FLAIR sequences,
which have an increased sensitivity for tuber identifi-
cation,23,24we failed to find a significant relationship
with tuber localization and ASD. A number of expla-
nations exist for these findings, including methodo-
logic flaws that may be inherent to assessment of
cortical tubers by MRI in TSC. Histologic evidence
suggests that brain pathology in TSC extend beyond
the limits of cortical tubers visualized on MRI.32,33
Our inability to demonstrate a clear relationship be-
tween cortical tuber burden and ASD could repre-
sent our inability to accurately evaluate the
widespread cortical disorganization in these patients.
Indeed, a study assessing gray and white matter vol-
umes, in conjunction with tuber burden, found that
only abnormalities in volume and in not burden were
predictive of memory deficits in patients with TSC.34
Thus, although cortical tuber burden evaluated by
MRI may be a better marker of brain disease in TSC
than cortical tuber size or number alone, it still may
fall short of ascertaining the full extent of the neuro-
pathology of TSC.19,25,35
Cyst-like cortical tubers are a neuroanatomic
finding in TSC, the prognostic significance of which
is under investigation.36The mechanism by which
cyst-like cortical tubers develop is unknown, as is
their natural history. Here we find that cyst-like tu-
bers are more common and more numerous and af-
fect more brain regions in patients with TSC/ASD.
Further investigations examining the relationship be-
tween cyst-like tubers and epileptogenic foci could
reveal a pathophysiologic link between these lesions
and ASD. Because interictal epileptiform activity has
been hypothesized to alter cognition and behavior,
persistent electrophysiologic abnormalities related to
cyst-like tubers could contribute to the development
of ASD in TSC.37,38Epileptiform features, separate
from or in concert with ictal events, could provide
considerable dysfunction or “static” in the brain and
contribute to the high prevalence of ASD in
TSC.38,39One cannot rule out the possibility that
cyst-like tubers, EEG abnormalities, or the other risk
factors for ASD identified herein are markers for
more significant brain pathology in TSC, rather than
the etiologic basis for ASD in TSC. Several investiga-
tions have demonstrated a more severe neurologic
phenotype in patients with TSC2 mutations,10,12,26,27
including increased prevalence of cyst-like tubers.36
Here, results of our multiple regression analysis dem-
onstrate that TSC mutation type as well as temporal
lobe epileptiform activity were associated with ASD,
providing evidence that these variables are indepen-
dent predictors of ASD in TSC. However, this find-
ing does not exclude that possibility that the
pathogenesis of ASD in this population may result
from a more global brain dysfunction.
Taken together, our data lend support for an un-
derlying role of genetic, physiologic, and structural
abnormalities in the development of ASD in TSC,
although none of these can fully explain the high
prevalence of ASD in this population. Further inves-
tigations aiming to elucidate the relationship be-
tween neuropathology in TSC and ASD may be
served well by using mouse models of TSC that ex-
hibit some degree of neuronal disorganization, in-
cluding the Tsc1 conditional knockout mouse.40
Statistical analysis was performed by Dr. Adam L. Numis with the guid-
ance of Dr. Elizabeth A. Thiele.
The authors thank P. Ellen Grant for consultation regarding the radio-
graphic analysis of these data.
Dr. Numis, Dr. Major, Dr. Montenegro, D.A. Muzykewicz, and Dr.
Pulsifer report no disclosures. Dr. Thiele serves on the Board of Directors
of the Tuberous Sclerosis Alliance and on scientific advisory boards for the
Angelman Syndrome Foundation and the Charlie Foundation; serves on
the speakers’ bureau for and has received funding for travel and speaker
honoraria from UCB; serves as a consultant for Lundbeck Inc.; and re-
ceives research support from Lundbeck Inc., the NIH, and the Tuberous
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Neurology 76 March 15, 2011