Article Type : Case Report
Authors : Ayala-Alvarez JC, Quiroz Saavedra ADR, Vazquez-Urrutia JR, and Angel AGD
Keywords : Leukoencephalopathy; Neurological microangiopathy; Cysts; Ribosomopathies
Leukoencephalopathy with cerebral
calcifications and cysts (LCC), was first reported in 1996 by Labrune,
categorized as a rare neurological microangiopathy with leukoencephalopathy,
intracranial calcifications and cysts identified in brain imaging(1). Reported
as an autosomal recessive genetic disorder caused by a bi-allelic variant in
SNORD118.
Leukoencephalopathy with cerebral calcifications and
cysts (LCC), was first reported in 1996 by Labrune, categorized as a rare
neurological microangiopathy with leukoencephalopathy, intracranial
calcifications and cysts identified in brain imaging [1]. Reported as an
autosomal recessive genetic disorder caused by a bi-allelic variant in
SNORD118, encoding for the box C/D U8 small nucleolar RNA, factor important for
maturation of 28S and 5.8S rRNAs, which form 60S large subunit, classifying the
disorder under the Ribosomopathies [2]. Also intramolecular interaction
mechanism of SNORD118 5´end and 3´extension may show nature of series of
variants, as the ones observed in LCC (4). Subsequent genetic analysis of our
patient revealed SNORD118 Heterozygous pathogenic variant (n.72A>G) and
heterozygous variant of uncertain significance (n.90C>T), this last variant
not reported in the literature. Clinical manifestations of the disease are
heterogenous, as they can present as seizures, cerebellar ataxia, extrapyramidal
symptoms, and cognitive decline, progressing to disability due to quadriplegia
or brainstem disfunction [3]. Imaging recognition of extensive signal
abnormalities of periventricular and deep white matter on MRI, as well as
supratentorial and cerebellar cysts are suggestive findings of the disease. CT
scan is characterized by progressive calcifications in the basal ganglia and
cerebellar nuclei and supratentorial white matter. In this case report we
present the first patient with LCC and multiple endocrinopathies, consistent
with hypothyroidism and precocious puberty. We also found a novel heterozygous
variant in SNORD118 (n.90C>T) which may be involved in the phenotype of this
disease. We also describe the current known variants of SNORD118 (Table 1).
We present an 8 year old girl, known with central hypothyroidism and precocious puberty since 7 years of age.. She is the product of a first pregnancy with no complications, born at 39 weeks of gestation to a healthy non-consanguineous couple. Weight was 2.695 kg, height was 1.6 ft, APGAR score was 9. Psicomotor development: Holds head erect steady at 4 months (normal: 3weeks - 4 months), sits alone at 6 months (normal: 5-9 months), crawling a 9 months (normal: 5-11 months), walking at 15 months (normal: 9-17 months), first word at 12 months (normal: 10-14 months), bladder and bowel control at 30 months (normal: 24-30 months). Currently in third grade of elementary school with psychomotor deficit characterized by altered fine motor skills, writing, drawing, shirt buttoning and teeth brushing. Constipation, dry skin, fatigue, presence of pubic hair and breast growth was also seen on examination. She presented with seizures at the age of 3 years old, characterized as generalized tonic seizures with 2 minutes of duration, postictal vomiting and somnolence. She presented recurrent seizures in 2 other periods with therapy adjustment.
At first managed with Valproate, suspended due to
thrombocytopenia, transitioning to Levetiracetam and Oxcarbazepine, with bad
control of seizures. On next visit Vigabatrin was added and Levetiracetam was
suspended with apparent control of seizures until October 2021. Currently
managed with Topiramate 200mg every 24 hrs, Oxcarbazepine 300mg in the morning
and 600mg during the night and Risperidone 1mg/ml, 0.25ml in the morning and
0.5ml during the night, levothyroxine 50mcg 1 every 24 hr, Leuprorelin 11.25mg
every 84 days. On examination patient is awake, active, cooperative, mildly
distracted during interrogation, mental functions with altered calculus, she
does not perform sums or subtractions of 1 digit. Judgment, abstraction and
comprehension compatible with intellectual disability. Symmetric gaze, presence
of horizontal and vertical nystagmus,
rest of cranial nerve functions intact, motor function 5/5, myotatic
reflex ++ on right side, +++ on left side. Inversion of the left foot while
walking, no tandem, dysmetria with predominance on left side of the body.
Altered gross and fine coordination. Follow up laboratory exams are showed in
Table 1, consistent with normal FSH, LH and thyroid function. Currently patient
is euthyroid due to use of levothyroxine and symptoms consistent with
hypothyroidism, such as constipation, dry skin and fatigue have subsided. The
presence of pubic hair and breast growth ceased and are currently appropriate
for age. Brain gadolinium-enhanced
magnetic resonance imaging study revealed increased signal in bilateral deep
white matter substance, parietal subependymal region and bilateral frontal
lobes in semioval centers. Hyperintense on FLAIR and T2 sequences, without
contrast enhancement and right frontal cortex focal atrophy (Figure 1).
Electroencephalogram showed epileptic activity in left temporoparietooccipital
region. Subsequent genetic analysis revealed SNORD118 Heterozygous pathogenic
variant (n72A>G) and heterozygous variant of uncertain significance
(n90C>T), confirming diagnosis of LCC. As such, complete genetic sequencing
of the parents revealed a SNORD118 gene heterozygous variant relevant for
n.72A>G variant in the father and heterozygous variant of uncertain
significance (n90C>T) in the mother's sequence analysis.
Leukoencephalopathy with cerebral calcifications and
cysts, also known as Labrune Syndrome, was first described in 1996. This
disease normally presents extensive calcifications, leukodystrophy and
formation of parenchymal cysts. Neuroimaging features are reported as
asymmetric calcifications predominantly in the basal ganglia, thalami,
brainstem, dentate nuclei and white matter with diffuse leukoencephalopathy,
multiple cysts and bleeding in parenchyma or cysts. Susceptibility-weighted
imaging of patients often demonstrates small bleeding and microcalcifications,
what leads to thinking that there could be an abnormality within microvessels.
SNORD118, located in chromosome 17p13.1 encodes the box C/D snoRNA U8, which is
an RNA involved in the biogenesis and normal function of ribosome. Currently
symptomatic treatment is the primary therapy for LCC. Antiepileptics,
corticosteroids, and surgical techniques such as cystic puncture, resection and
cyst ventriculo-peritoneal shunt are among the options which may temporarily
relieve the symptoms. The first description of anti-VEGF therapy in a patient
with LCC was described by Fay et.al, demonstrating clinical and radiological
improvement with no adverse events. VEGF is a promoter of neovascularization
and vascular permeability, and its inhibition has reported to reduce exudate
and cysts in ocular disorders such as macular edema and Coats disease [4].
We report the first case of a childhood LCC with
heterozygous variants in SNORD118, with multiple endocrinopathies
(hypothyroidism and precocious puberty) since onset of disease, to the best of
our knowledge this is the first case reported of LCC with an added multiple
endocrinopathy.
Patient’s tutors have no conflict of publication of
information related to the case. Written informed consent was obtained from the
patient for the publication of this case report.
We would like to acknowledge Dr. Adriana González for
her insight, expertise, and support in this case.
Authors have nothing to disclose.