Table 2.

Disorders of Interest in the Differential Diagnosis of CA-VA Deficiency

GeneDisorderMOIClinical Characteristics
BTD
HLCS 		Multiple carboxylase deficiency (biotinidase deficiency & holocarboxylase synthetase deficiency) (OMIM 253270)ARIf untreated, children w/profound defic usually exhibit neurologic abnormalities (seizures, lethargy, & muscular hypotonia), cutaneous abnormalities, ataxia, DD, vision problems, & hearing loss.
CPS1
NAGS 		CPS1 deficiency, NAGS deficiency, & other urea cycle defectsARInfants w/severe defic are nl at birth but rapidly develop cerebral edema w/lethargy, poor feeding, hyper- or hypoventilation, hypothermia, seizures, neurologic posturing, & coma. In milder (or partial) defic the elevations of plasma ammonia concentration & symptoms are often subtle (1st recognized clinical episode may not occur for months or decades).
PC Pyruvate carboxylase deficiency ARFailure to thrive, DD, recurrent seizures, & metabolic acidosis 1
UQCRC2 Ubiquinol-cytochrome c oxidoreductase core 2 subunit deficiency (OMIM 615160)ARNeonatal-onset severe metabolic acidosis, hyperammonemia & hypoglycemia w/poor sucking & tachypnea but normal development or only mild DD despite recurrent metabolic crises; hepatocellular dysfunction also reported in 1 person

AR = autosomal recessive; CPS1 = carbamoylphosphate synthetase I; DD = developmental delay; MOI = mode of inheritance; NAGS = N-acetyl glutamate synthase; nl = normal

1.

Three clinical types are recognized: Type A (infantile form), in which most affected children die in infancy or early childhood; Type B (severe neonatal form), in which affected infants have hepatomegaly, pyramidal tract signs, and abnormal movement and die within the first three months of life; and Type C (intermittent/benign form), in which affected individuals have normal or mildly delayed neurologic development and episodic metabolic acidosis.

From: Carbonic Anhydrase VA Deficiency

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