Methylcobalamin deficiency type cblG

General Information (adopted from Orphanet):

Synonyms, Signs: METHIONINE SYNTHASE DEFICIENCY
HMAG
METHYLCOBALAMIN DEFICIENCY, cblG TYPE
HOMOCYSTINURIA-MEGALOBLASTIC ANEMIA DUE TO DEFECT IN COBALAMIN METABOLISM, cblG COMPLEMENTATION TYPE
Functional methionine synthase deficiency type cblG
Number of Symptoms 23
OrphanetNr: 2170
OMIM Id: 250940
ICD-10: E72.1
UMLs:
MeSH:
MedDRA:
Snomed:

Prevalence, inheritance and age of onset:

Prevalence: 33 cases [Orphanet]
Inheritance: Autosomal recessive
[Orphanet]
Age of onset: All ages
[Orphanet]

Disease classification (adopted from Orphanet):

Parent Diseases: Genetic thrombotic microangiopathy
 -Rare genetic disease
Homocystinuria without methylmalonic aciduria
 -Rare genetic disease
 -Rare hematologic disease
 -Rare neurologic disease
Thrombotic microangiopathy
 -Rare renal disease

Symptom Information: Sort by abundance 

1
(HPO:0002156) Homocystinuria 12 / 7739
2
(HPO:0000639) Nystagmus rare [HPO:skoehler] 555 / 7739
3
(HPO:0000618) Blindness rare [HPO:skoehler] 124 / 7739
4
(HPO:0000572) Visual loss 272 / 7739
5
(HPO:0002370) Poor coordination 15 / 7739
6
(HPO:0001288) Gait disturbance 318 / 7739
7
(HPO:0001263) Global developmental delay 853 / 7739
8
(HPO:0001250) Seizures 1245 / 7739
9
(HPO:0001249) Intellectual disability 1089 / 7739
10
(HPO:0008872) Feeding difficulties in infancy 153 / 7739
11
(HPO:0001508) Failure to thrive 454 / 7739
12
(HPO:0001889) Megaloblastic anemia 28 / 7739
13
(HPO:0003223) Decreased methylcobalamin 11 / 7739
14
(HPO:0003524) Decreased methionine synthase activity 9 / 7739
15
(HPO:0002160) Hyperhomocystinemia 10 / 7739
16
(HPO:0003658) Hypomethioninemia 6 / 7739
17
(HPO:0010547) Muscle flaccidity 466 / 7739
18
(HPO:0008947) Infantile muscular hypotonia 482 / 7739
19
(HPO:0001252) Muscular hypotonia 990 / 7739
20
(HPO:0001324) Muscle weakness 859 / 7739
21
(HPO:0000007) Autosomal recessive inheritance 2538 / 7739
22
(HPO:0002059) Cerebral atrophy 171 / 7739
23
(HPO:0003593) Infantile onset 249 / 7739

Associated genes:

ClinVar (via SNiPA)

Gene symbol Variation Clinical significance Reference

Additional Information:

Description: (OMIM) Homocystinuria and megaloblastic anemia is an autosomal recessive inborn error of metabolism resulting from defects in the cobalamin (vitamin B12)-dependent pathway that converts homocysteine to methionine, which is catalyzed by methionine synthase. Clinical features are somewhat variable, but ...
Clinical Description OMIM Thomas et al. (1985) and Rosenblatt et al. (1987) reported a boy with methylcobalamin deficiency who presented at age 6 weeks with lethargy, staring spells and vomiting after varicella infection. He was hypotonic and unresponsive to stimuli and ...
Molecular genetics OMIM Gulati et al. (1996) analyzed the molecular basis for methionine synthase deficiency in cell lines derived from 2 cblG patients. The 79/76 cell line had low levels of methionine synthase activity and a diminished level of methionine synthase ...