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| Bilateral congenital or childhood onset cataracts v2.6 | GALM |
Zornitza Stark gene: GALM was added gene: GALM was added to Cataracts. Sources: Expert list Mode of inheritance for gene: GALM was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: GALM were set to 30451973; 30910422 Phenotypes for gene: GALM were set to type IV galactosaemia Review for gene: GALM was set to AMBER Added comment: Homozygous and compound heterozygous variants (missense, nonsense and frameshift) found in 8 Japanese patients from unrelated families with unexplained galactosaemia. (No variants in GALT, GALK1, and GALE). This is therefore type IV galactosaemia. In vitro expression analysis and enzyme activity assay of the patients’ peripheral blood mononuclear cells showed total lack of or compromised expression of GALM protein. Loss-of-function mechanism. One homozygote for one of these variants p.(Gly142Arg) in gnomAD (African population). (Wada, Y. et al 2019; PMID: 30451973) In vitro expression assay and an enzyme activity assay of 67 GALM variants, taken from ExAc database (missense, nonsense, frameshift and splice). 30 variants concluded to be pathogenic due to no protein expression or faint expression. 5 variants with mildly lower levels were determined as likely pathogenic. All concluded to be loss-of-function mechanism. Incidence of galactosaemia by GALM deficiency is comparable to that of other galactosaemias. Carrier frequency and incidence was estimated for different populations. (Iwasawa, S. et al. (2019); PMID: 30910422) Note only two of the reported individuals had cataracts. Sources: Expert list |
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