A CRYPTIC DUPLICATION 22q13.31 TO qter LEADS TO A DISTINCT PHENOTYPE WITH MENTAL RETARDATION, MICROCEPHALY AND MILD FACIAL DYSMORPHISM
GENETIC COUNSELING
Authors: Peeters, H.; Vermeesch, J.; Fryns, J. P.
Abstract
A cryptic duplication 22q13.31 to qter leads to a distinct phenotype with mental retardation, microcephaly and mild facial dysmorphism: We present a girl with a terminal 22q duplication due to all unbalanced chromosomal translocation: 46, XX, der(22)(qter -> q13.31 :: p11 -> qter). She presented with mild to moderate mental retardation. autism spectrum disorder, microcephaly and mild dysmorphic facial features. Because of nasal speech and mental retardation. FISH analysis for the DiGeorge/VCFS region was performed. In this analysis, an extra signal for the control probe LSI ARSA (22q13) on the short arm of one of the chromosomes 22 revealed the terminal duplication 22qter. The duplication was confirmed by means of IMb array-CGH and Further delineated as a 5.5 Mb region: 46, XX, dup(22)(q13.31qter)(CTA-268H5 -> CTB-99K24)x3. Important phenotypic variability has been described among patients with terminal 22q duplications. However, by considering the present patient and a careful selection of literature reports describing pure trisomy 22qter and comparably small duplicated regions 22q13.3 to qter, we find evidence tor a consistent clinical presentation: mild to moderate mental retardation, microcephaly and similar mild dysmorphic Features. Furthermore we conclude that small terminal duplications of chromosome 22q may be more common than generally assumed but may remain undetected by high resolution karyotyping. The application of array-CGH in patients with mental retardation and only very mild dysmorphism may allow to detect small 22qter duplications more frequently.
Spectrum of ARSA variations in Asian Indian patients with Arylsulfatase A deficient metachromatic leukodystrophy
JOURNAL OF HUMAN GENETICS
Authors: Narayanan, Dhanya Lakshmi; Matta, Divya; Gupta, Neerja; Kabra, Madhulika; Ranganath, Prajnya; Aggarwal, Shagun; Phadke, Shubha R.; Datar, Chaitanya; Gowrishankar, Kalpana; Kamate, Mahesh; Jain, Jamal Mohammed Nurul; Dalal, Ashwin
Abstract
Metachromatic leukodystrophy due to Arylsulfatase A enzyme deficiency is an autosomal recessive disorder caused by biallelic variations in ARSA gene. Till date 186 variations have been reported in ARSA gene worldwide, but the variation spectrum in India is not known. The aim of this study was to identify the variation profile in Indian patients presenting with features of Arylsulfatase A deficient metachromatic leukodystrophy. We sequenced the ARSA gene in 51 unrelated families and identified 36 variants out of which 16 were novel. The variations included 23 missense, 3 nonsense, and 6 frameshift variants (3 single-base deletions and 3 single-base duplications), 1 indel, one 3 bp deletion, and 2 splice site variations. The pathogenicity of the novel variations was inferred with the help of mutation prediction softwares like MutationTaster, SIFT, Polyphen-2, PROVEAN, and HANSA. The effects of the identified sequence variants on the protein structure were studied using in silico methods. The most common variation was c.931 C > T(p.Arg311*), found in 11.4% (14 out of 122 alleles) of the tested individuals. To the best of our knowledge, this study is the first of its kind in India with respect to the size of the cohort and the molecular diagnostic method used and one of the largest cohorts of metachromatic leukodystrophy studied till date.