Low anal sphincter tone in infantile-onset Pompe Disease: an emerging clinical issue in enzyme replacement therapy patients requiring special attention

Infantile-onset Pompe disease with neonatal debut: A case report and literature review

RATIONALE

Infantile-onset Pompe disease, also known as glycogen storage disease type II, is a progressive and fatal disorder without treatment. Enzyme replacement therapy with recombinant human acid alpha-glucosidase (GAA) enhances survival; however, the best outcomes have been achieved with early treatment.

PATIENT CONCERNS

We report a case of a newborn with infantile-onset Pompe disease diagnosed in the first days of life who did not undergo universal neonatal screening. The patient was asymptomatic, with a general physical examination revealing only a murmur. The clinical presentation was dominated by the neonatal detection of hypertrophic cardiomyopathy, without hypotonia or macroglossia.

DIAGNOSES

Pompe disease was confirmed in the first week of life by GAA activity in dried blood spots, and a GAA genetic study showed the homozygous mutation p.Arg854X.

INTERVENTIONS

Parents initially refused replacement therapy.

OUTCOMES

The patient experienced recurrent episodes of ventricular fibrillation during central line placement and could not be resuscitated.

LESSONS

Although Pompe disease is rare, and universal screening has not been established, neonatologists should be alerted to the diagnosis of Pompe in the presence of hypertrophic cardiomyopathy. Diagnosis is achieved in a few days with the aid of dried blood spots.

The humanistic burden of Pompe disease: are there still unmet needs? A systematic review

BACKGROUND

Humanistic burden considers the impact of an illness on a patient's health-related quality of life (HRQoL), activities of daily living (ADL), caregiver health, and caregiver QoL. Humanistic burden also considers treatment satisfaction and adherence to treatment regimens. Pompe disease is an autosomal recessive, progressive, multisystemic neuromuscular disease. Approval of enzyme-replacement therapy (ERT) markedly improved prognosis for patients, but considerable morbidity and a substantial humanistic burden remain. This article characterizes the humanistic burden of Pompe disease through a systematic literature review.

METHODS

A systematic search of MEDLINE® and Embase® with back-referencing and supplementary literature searches was performed to retrieve data from interventional and non-interventional studies on the humanistic burden of Pompe disease. Publications were screened according to predefined criteria, extracted, and assessed for quality. Extracted data were narratively synthesized.

RESULTS

No publications on the humanistic burden of infantile-onset Pompe disease (IOPD) were identified. As such, of 17 publications included here, all are in patients with late-onset Pompe disease (LOPD). Thirteen publications were initiated after approval of ERT, two were initiated before, and two overlapped the approval of ERT. The review shows that LOPD patients have a significantly lower HRQoL than the general population, even if treated with ERT. On transitioning to ERT, treatment was associated with improvement in the physical component score of the SF-36 and fatigue, although the SF-36 mental component score remained stable. Physical HRQoL remained below population norms after 4 years of ERT. Significantly more ERT-treated patients reported pain than controls, and bodily pain worsened in later years following ERT initiation. Treatment-naïve LOPD patients had significantly poorer ADL functioning compared with the general population, although ERT stabilized deteriorating functioning impairment. ERT studies showed caregivers provide 17.7 h/week informal care on average. Fifty percent, 40% and <20% of caregivers reported mental health, physical health, and financial/relational problems, respectively. In ERT-naïve patients, wheelchair use and home ventilatory support was associated with lower physical HRQoL and ADL functioning. In ERT-treated patients, key factors predicting worse HRQoL and ADL functioning were higher respiratory distress, poorer sleep quality, greater pain, and more fatigue.

CONCLUSIONS

Pompe disease has a substantial humanistic burden, with strong inter-relationships among and between humanistic burden parameters and clinical progression.

Postmortem Findings and Clinical Correlates in Individuals with Infantile-Onset Pompe Disease

Pompe disease (OMIM 232300), a glycogen storage disorder caused by deficiency in the lysosomal enzyme acid alpha-glucosidase (EC 3.2.1.20), results in weakness and cardiomyopathy in infants affected with the classic form. Although the primary disease manifestations are due to glycogen accumulation in skeletal and cardiac muscle, glycogen also accumulates in a variety of additional tissues. To improve our understanding of disease pathogenesis in long-term survivors, we reviewed postmortem results for three infants with the classic form of Pompe disease. We have observed a number of new complications in long-term survivors of infantile-onset Pompe disease, and we focused this postmortem study on pathological correlates. Findings in survivors include cardiac arrhythmias, which may be related to glycogen accumulation in cardiac conduction tissue; urinary incontinence, likely due to glycogen accumulation in smooth muscle; and refractory errors, possibly related to accumulation in ocular structures. These observations provide potential pathophysiologic correlates for complications in long-term survivors of infantile Pompe disease.