Clinical Characteristics, Molecular Profile, and Outcomes in Indian Patients with Glutaric Aciduria Type 1.

Glutaric acidemia type 1 (GA-1, OMIM 231670) is an autosomal recessive inborn error of metabolism caused by the deficiency of glutaryl-coenzyme A (CoA) dehydrogenase with most children presenting in infancy with encephalopathy, dystonia, and macrocephaly. In this article, we presented the clinical characteristics, molecular profile, and outcomes in 29 unrelated families with affected children (30 cases total). The mean age at onset of illness was 10 months (±14.58), whereas the mean age at referral for molecular diagnosis was 29.44 months (±28.11). Patients were residents of nine different states of India. Clinical presentation varied from acute encephalitis followed by neuroregression and chronic/insidious developmental delay. Neurological sequelae varied from asymptomatic (no sequelae, 2 patients) to moderate (5 patients) and severe (23 patients) sequelae. All patients underwent blood tandem mass spectrometry (TMS on dried blood spots) and/or urine gas chromatography mass spectrometry (GCMS). Neuroimaging demonstrated batwing appearance in 95% cases. Sanger's sequencing of GCDH , covering all exons and exon-intron boundaries, was performed for all patients. Variants identified include 15 novel coding variants: p.Met100Thr, p.Gly107Ser, p.Leu179Val, p.Pro217Ser, p. Phe236Leufs*107, p.Ser255Pro, p.Met266Leufs*2, p.Gln330Ter, p.Thr344Ile, p.Leu345Pro, p.Lys377Arg, p.Leu424Pro, p.Asn373Lys, p.Lys377Arg, p.Asn392Metfs*9, and nine known genetic variants such as p.Arg128Gln, p.Leu179Arg, p.Trp225Ter, p.Met339Val, p.Gly354Ser, p.Arg402Gln, p.Arg402Trp, p.His403Tyr, and p.Ala433Val (Ensembl transcript ID: ENST00000222214). Using in silico analysis, genetic variants were shown to be affecting the residues responsible for homotetramer formation of the glutaryl-CoA dehydrogenase protein. Treatment included oral carnitine, riboflavin, protein-restricted diet, lysine-deficient special formulae, and management of acute crises with intravenous glucose and hydration. However, the mortality (9/30, 27.58%) and morbidity was high in our cohort with only two patients affording the diet. Our study is the largest multicentric, genetic variant-proven series of glutaric aciduria type 1 from India till date.

Clinical, biochemical and mutation profile in Indian patients with Sandhoff disease.

Sandhoff disease (SD) is an autosomal recessive neurodegenerative lysosomal storage disorder caused by mutations in HEXB gene. Molecular pathology is unknown in Indian patients with SD. The present study is aimed to determine mutations spectrum and molecular pathology leading to SD in 22 unrelated patients confirmed by the deficiency of ß-hexosaminidase-A and total-hexosaminidase in leukocytes. To date, nearly 86 mutations of HEXB have been described, including five large deletions. Over all we have identified 13 mutations in 19 patients, eight of which were novel, including two missense mutations [c.611G>A (p.G204E), c. 634A>T (p.H212Y)], two nonsense mutations [c.333G>A (p.W111X), c.298C>T (p.R100X)], one splice site mutation c.1082+5 G>T, two small in-frame deletions [c.534_541delAGTTTATC (p.V179RfsX10), c.1563_1573delTATGGATGACG (p.M522LfsX2)] and one insertion c.1553_1554insAAGA (p.D518EfsX8). We have also identified previously known, five sequence variations leading to amino acid changes [c.926G>A (p.C309Y), c.1597C>T (p.R533C)], one nonsense mutation c.850 C>T (p.R284X), one splice site mutation c.1417+1 G-A and one insertion c.1591_1592insC (p.R531TfsX22). Mutation was not identified in three patients. We observed from this study that mutation c.850C>T (p.R284X) was identified in 4/19 (21%) patients which is likely to be the most common mutation in the country. This is the first study providing insight into the molecular basis of SD in India.

Identification of novel mutations in HEXA gene in children affected with Tay Sachs disease from India.

Tay Sachs disease (TSD) is a neurodegenerative disorder due to ß-hexosaminidase A deficiency caused by mutations in the HEXA gene. The mutations leading to Tay Sachs disease in India are yet unknown. We aimed to determine mutations leading to TSD in India by complete sequencing of the HEXA gene. The clinical inclusion criteria included neuroregression, seizures, exaggerated startle reflex, macrocephaly, cherry red spot on fundus examination and spasticity. Neuroimaging criteria included thalamic hyperdensities on CT scan/T1W images of MRI of the brain. Biochemical criteria included deficiency of hexosaminidase A (less than 2% of total hexosaminidase activity for infantile patients). Total leukocyte hexosaminidase activity was assayed by 4-methylumbelliferyl-N-acetyl-ß-D-glucosamine lysis and hexosaminidase A activity was assayed by heat inactivation method and 4-methylumbelliferyl-N-acetyl-ß-D-glucosamine-6-sulphate lysis method. The exons and exon-intron boundaries of the HEXA gene were bidirectionally sequenced using an automated sequencer. Mutations were confirmed in parents and looked up in public databases. In silico analysis for mutations was carried out using SIFT, Polyphen2, MutationT@ster and Accelrys Discovery Studio softwares. Fifteen families were included in the study. We identified six novel missense mutations, c.340 G>A (p.E114K), c.964 G>A (p.D322N), c.964 G>T (p.D322Y), c.1178C>G (p.R393P) and c.1385A>T (p.E462V), c.1432 G>A (p.G478R) and two previously reported mutations. c.1277_1278insTATC and c.508C>T (p.R170W). The mutation p.E462V was found in six unrelated families from Gujarat indicating a founder effect. A previously known splice site mutation c.805+1 G>C and another intronic mutation c.672+30 T>G of unknown significance were also identified. Mutations could not be identified in one family. We conclude that TSD patients from Gujarat should be screened for the common mutation p.E462V.

Effect of deferiprone on urinary zinc excretion in multiply transfused children with thalassemia major.

A prospective multi-centric study was conducted to determine if iron-chelating agent deferiprone also chelates zinc. Twenty four-hour urinary zinc levels were compared in multiply transfused children with thalassemia major not receiving any chelation therapy (Group A, n = 28), those receiving deferiprone (Group B, n = 30) and age and sex-matched controls of subjects in Group B (Group C, n = 29) by a colorimetric method. The 24-hour mean urinary excretion of zinc was significantly higher in Group B than in the other two groups indicating that deferiprone chelates zinc.