The impact of coronavirus disease 2019 (COVID-19) on patients with primary immunodeficiency (PID) remains insufficiently characterized. This study aimed to describe the clinical manifestations, disease course, and outcomes of COVID-19 in patients with PID. Adult patients with PID who had COVID-19 infection between March 2020 and August 2022 were screened. Demographic and clinical data were retrospectively collected from institutional databases, and additional information was obtained through a patient questionnaire. A total of 36 patients (19 males, 17 females; median age: 36.5 years) with various PID subtypes were included: 24 with common variable immunodeficiency (CVID), 3 with cytotoxic T-lymphocyte-associated protein-4 haploinsufficiency, 3 with X-linked agammaglobulinemia (XLA), 2 with hypogammaglobulinemia, 1 with lipopolysaccharide-responsive and beige-like anchor protein deficiency, 1 with DiGeorge syndrome, 1 with mitochondrial neurogastrointestinal encephalomyopathy syndrome, and 1 with CVID-like capillary malformation-arteriovenous malformation syndrome 2. Overall, 63.9% (n = 23) were managed as outpatients, while 36.1% (n = 13) required hospitalization. Admission to the intensive care unit was required in 19.4% (n = 7) of the cases. The overall case fatality rate was 8.3% (n = 3), which is higher than the rate observed in the general population. Although the majority experienced a mild clinical course, patients with XLA exhibited prolonged symptoms and persistent seropositivity. Risk factors associated with hospitalization included lymphopenia, elevated C-reactive protein and ferritin levels, dyspnea, COVID-19 Reporting and Data System score ≥ 4 on imaging, need for supplemental oxygen, prolonged symptoms, and extended polymerase chain reaction positivity. A subset of adult patients with PID may be at increased risk for severe COVID-19.

Combined oxidative phosphorylation deficiency 6 (COXPD6) is a severe mitochondrial encephalomyopathy resulting from a mutation in the X-linked apoptosis-inducing factor mitochondrion-associated 1 (AIFM1) gene. The AIFM1 gene located on chromosome Xq26.1, encodes apoptosis inducing factor (AIF), a flavin adenine dinucleotide (FAD)-dependent nicotinamide adenine dinucleotide (NADH) oxidoreductase, which is involved in the process of oxidative phosphorylation and mitochondrial-derived programmed cell death in the nucleus. COXPD6 patients have significant end-organ involvement of the central nervous, peripheral nervous, respiratory, and gastrointestinal systems, manifested by seizures, hypotonia, psychomotor delay, muscle weakness, and wasting. We present an 11-year-old child with AIFM1-related COXPD6 who underwent posterior spinal fusion for progressive neuromuscular kyphoscoliosis. We explore the genetic history of this mitochondrial disorder, review a detailed anesthetic approach to perioperative management including use of the novel benzodiazepine, remimazolam, and discuss anesthetic considerations in these patients.

Variants in the X-linked gene AIFM1 (apoptosis-inducing factor mitochondria-associated 1) are associated with a highly variable clinical presentation that encompasses motor neuropathy, ataxia, encephalopathies, deafness, and cognitive impairment. AIFM1 encodes a mitochondrial flavin adenine dinucleotide (FAD)-dependent nicotinamide adenine dinucleotide (NADH) oxidoreductase, with roles in the regulation of respiratory complex assembly and function, production of reactive oxygen species, and the coordination of a caspase-independent type of apoptosis known as parthanatos. In this report, we describe a missense AIFM1 variant (absent in reference population databases; c.506C > T, p.Pro169Leu) identified in the proband and sibling of a family with three affected males. The proband, his brother, and their maternal uncle all exhibited severe multisystem pathology, metabolic acidosis, and early demise. Metabolic testing on the proband revealed normal activity of the pyruvate dehydrogenase complex in skin fibroblasts. Absent or partial deficiency of cytochrome c oxidase was found in muscle fibers, however, supporting a Complex IV mitochondrial deficiency. Functional studies carried out on fibroblasts from the proband demonstrated reduced steady state levels of the AIFM1 protein, decreased Complex I subunit abundance, elevated sensitivity to the apoptosis inducer staurosporine, and increased nuclear condensation when grown in galactose-containing media. The reduced abundance of AIFM1 in the patient cells could not be stabilized with riboflavin or protease inhibitor treatment. Together, these findings suggest that the normal function of the AIFM1 gene product within mitochondria, and its response to apoptotic stimuli, are impaired by this variant, likely accounting for the severity of the phenotype seen in these patients. These findings also imply tissue-specific effects of this variant on different mitochondrial complexes. This study expands the genetic and phenotypic spectrum associated with AIFM1 variants, with the combination of exome sequencing and functional studies allowing a diagnosis to finally be confirmed for this family.

Mitochondrial disorders, although heterogeneous, are traditionally described as conditions characterized by encephalomyopathy, hypotonia, and progressive postnatal organ failure. Here, we provide a systematic review of Linear Skin Defects with Multiple Congenital Anomalies (LSDMCA), a rare, unconventional mitochondrial disorder which presents as a developmental disease; its main clinical features include microphthalmia with different degrees of severity, linear skin lesions, and central nervous system malformations. The molecular basis of this disorder has been elusive for several years. Mutations were eventually identified in three X-linked genes, i.e., HCCS, COX7B, and NDUFB11, which are all endowed with defined roles in the mitochondrial respiratory chain. A peculiar feature of this condition is its inheritance pattern: X-linked dominant male-lethal. Only female or XX male individuals can be observed, implying that nullisomy for these genes is incompatible with normal embryonic development in mammals. All three genes undergo X-inactivation that, according to our hypothesis, may contribute to the extreme variable expressivity observed in this condition. We propose that mitochondrial dysfunction should be considered as an underlying cause in developmental disorders. Moreover, LSDMCA should be taken into consideration by clinicians when dealing with patients with microphthalmia with or without associated skin phenotypes.

AIFM1 encodes a mitochondrial flavoprotein with a dual role (NADH oxidoreductase and regulator of apoptosis), which uses riboflavin as a cofactor. Mutations in the X-linked AIFM1 were reported in relation to two main phenotypes: a severe infantile mitochondrial encephalomyopathy and an early-onset axonal sensorimotor neuropathy with hearing loss. In this paper we report two unrelated males harboring AIFM1 mutations (one of which is novel) who display distinct phenotypes including progressive ataxia which partially improved with riboflavin treatment. For both patients trio whole exome sequencing was performed. Validation and segregation were performed with Sanger sequencing. Following the diagnosis, patients were treated with up to 200 mg riboflavin/day for 12 months. Ataxia was assessed by the ICARS scale at baseline, and 6 and 12 months following treatment. Patient 1 presented at the age of 5 years with auditory neuropathy, followed by progressive ataxia, vermian atrophy and axonal neuropathy. Patient 2 presented at the age of 4.5 years with severe limb and palatal myoclonus, followed by ataxia, cerebellar atrophy, ophthalmoplegia, sensorineural hearing loss, hyporeflexia and cardiomyopathy. Two deleterious missense mutations were found in the AIFM1 gene: p. Met340Thr mutation located in the FAD dependent oxidoreductase domain and the novel p. Thr141Ile mutation located in a highly conserved DNA binding motif. Ataxia score, decreased by 39% in patient 1 and 20% in patient 2 following 12 months of treatment. AIFM1 mutations cause childhood cerebellar ataxia, which may be partially treatable in some patients with high dose riboflavin.