MUCOLIPIDOSIS TYPE II AND III: ECHOCARDIOGRAPHIC STUDY OF BRAZILIAN PATIENTS Alegra T 1 , Netto CB 2 , Souza CFM 2 , John AB 2 , Fagondes SC 2 , Schwartz IVD 1 1 Univ Federal do Rio Grande do Sul, Porto Alegre, Brazil 2 Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil Mucolipidosis (ML) types II and III are lysosomal diseases due to GlcNAc-phosphotransferase deficiency. Multisystem complications are present, including cardiopulmonary ones. Objective: To characterize echocardiographic abnormalities in Brazilian ML II/III patients. Methods: Cross-sectional study based on echocardiograms and medical records of ML II/III patients seen in a Brazilian Reference Center for LSD. Results: 9 patients were included; 5/9 ML II (aged 0.8 to 5 years) and 4/9 ML III (11-42 years). Clinical exam: systolic murmurs (n=6/8), cyanosis and dyspnea (n=1/8). Echocardiography: some alteration (n=9/9), systolic function preserved (n=9/9), patent foramen ovale (n=1/8, 10 months, MLII), mitral thickening (n=5/9, of whom one MLIII), mild mitral regurgitation (n=8/9), aortic valve thickening (n=3/9, and 2/3 MLIII). Two MLII patients presented LVH (aged 4 and 5 years). PH was present in 1/9 patient (MLIII, good evolution after treatment with Sildenafil and continuous positive airway pressure during sleep). Conclusion: Our study is unprecedented in Brazilian patients and confirmed that ML II/III patients may present HP, aortic and mitral thickening, and mitral insufficiency. Differently from the literature, LVH occurred in one child in our sample. Following these patients is important to detect early abnormalities, especially PH, which can be adequately treated. Support: CNPq, CAPES, Brazil MPS Network Mucolipidoses α/β (ML II or III) and γ (ML III) are lysosomal diseases (LSD) due to deficiency in GlcNAc-phosphotransferase, which is encoded by GNPTAB and GNPTG genes. Objective: To identify mutations in the GNPTAB and GNPTG genes in Brazilian patients with MLII/III. Methodology: We analyze both genes in gDNA of MLII/III patients diagnosed in a Brazilian Reference Center for diagnosis of LSD. Exons and flanking regions are being amplified by PCR and sequenced in automated sequencer ABI3100.. Results: Fifteen patients were included: 7/15 have ML II (4 female; mean age±SD=2.2±1.9 years) and 8/15, MLIII (1 female; mean age±SD=20.9 ±12.3); 2/15 were siblings. Both pathogenic mutations in GNPTAB were identified in 8/14 unrelated patients and only one in 4/14. The most frequent pathogenic mutation was c.3503_3504delTC (exon 19); two novel pathogenic mutations are being described: c.2269_2273delGAAAC; c.2808A>G. To date, 9/11 exons of GNPTG were sequenced in 14 patients, but only 3 different mutations were found in 4/28 alleles. Discussion/Conclusions: MLII/III α/β appears to be the most common type of ML in Brazil. Our findings suggests that, in our country, screening for GNPTAB gene mutations should be initiated in exon 19.