Abstract Details

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Abstract Details

Title Alpha- mannosidosis masquerading as familial macrocephaly

Topic Child Neurology and Developmental Neurology

Presentation(s) P14 - Poster Session 14 (8:00 AM-9:00 AM)

Poster/Presentation
Number 5-005

Objective

Describe a rare etiology of macrocephaly, along with a review of current diagnostic and therapeutic options.

Background

Alpha mannosidosis is an autosomal recessive lysosomal storage disease, resulting from a mutation in MAN2B1 gene. This mutation results in deficiency of alpha mannosidase enzyme. Current estimated prevalence is approximately 1 in 500,000 people worldwide. There is no clear genotype- phenotype correlation described for this rare condition

Design/Methods Case report and review of literature

Results

A 15-month-old girl presented for evaluation of asymptomatic macrocephaly. Past medical history was unremarkable, other than episodes of recurrent otitis media. She was on track for developmental milestones, with no evidence of regression. Her father and a five-year-old sibling were reportedly also macrocephalic but doing well otherwise.

On exam, she was large for her age with mild thickening of the facial features. Neurological exam was otherwise unremarkable. Detailed evaluation of her growth charts demonstrated a linear pattern of advancement across all growth parameters. At 15 months of age, she was above 100 percentile for weight, height and head circumference. A MRI brain was negative for any evidence for hydrocephalus, mass effect or midline shift. While familial macrocephaly was considered as a diagnosis, urine screening for lysosomal storage disease was performed, and returned positive. The absence of alpha-mannosidase by leukocyte testing was confirmatory for alpha mannosidosis.

Conclusions This case highlights the worldwide distribution of alpha mannosidosis, and the importance of clinician awareness in recognizing its phenotypic presentation. Though uncommon, lysosomal storage diseases should be on the differential for asymptomatic macrocephaly. Initial evaluation consists of ophthalmological exam, audiometry, skeletal assessment, abdominal ultrasound and developmental screening. Treatment is symptomatic management to improve quality of life. Novel therapeutic options focusing on enzyme replacement and bone marrow transplant, as well as ongoing studies for gene therapy have been described as potential interventions.

Authors/Disclosures
Surabhi Kaul, MD (MercyOne North Iowa Medical Center) PRESENTER	No disclosure on file
Shivika Chandra, MD, F�鶹��ýӳ�� (University of Texas Health Science Center at Houston)	The institution of Dr. Chandra has received research support from American Board of Psychiatry and Neurology Faculty Innovation in �鶹��ýӳ�� Award. The institution of Dr. Chandra has received research support from Michael J Fox Foundation.