[ALPK3 gene-related pediatric cardiomyopathy with craniofacial-skeletal features: a report and literature review].

Objective: To explore the clinical characteristics and mutation spectrum of ALPK3-related pediatric cardiomyopathy and craniofacial-skeletal abnormalities in children. Methods: The clinical data during a follow-up of 11 years including clinical features, echocardiogram, electrocardiogram, cardiac magnetic resonance, genetic testing, and other data of a child firstly diagnosed with ALPK3 gene-related cardiomyopathy and craniofacial-skeletal abnormalities in China were collected retrospectively. The literatures containing the keyword of "ALPK3 gene" published in the China National Knowledge Infrastructure, Wanfang database and PubMed were collected up to November 2020. Then, the clinical features and gene mutations of ALPK3 gene-related pediatric cardiomyopathy with craniofacial-skeletal features were summarized. Results: A female patient aged 10 months who presented with an enlarged heart for 2 months, was admitted to the hospital and initially diagnosed with endocardial elastic fibrosis. The echocardiography showed features of dilated left ventricle (LV) and LV systolic dysfunction. Low-set ears, webbed neck, a grade 2/6 systolic murmur at lower left sternal area and bilateral absent flexion creases of dig were observed. After treatment, the size and function of the heart recovered to normal at age 13 months. However, the ventricular septum and LV wall were thicker than normal values. Then, the diagnosis was revised to hypertrophic cardiomyopathy(HCM) and suspected congenital malformation syndrome. LV hypertrophy (LVH) progressed slowly before the age of 8 years and then progressed rapidly. At age 9 years, compound heterozygous ALPK3 mutations (c.721dup, p.Y241Lfs*42(exon 1) and c.4840C>T, p.R1614*(exon 10)) were detected in the proband and the mutations had not been reported previously. Then, the final diagnosis of ALPK3 gene-related pediatric cardiomyopathy with craniofacial-skeletal features was made. During the follow up of 11 years, regular follow-up echocardiographic images showed progressive LVH. At age 11 years, electrocardiogram showed LVH, ST-T changes in multiple-lead, T wave inversion, and prolonged QT intervals. Cardiac magnetic resonance showed biventricular hypertrophy and late gadolinium enhancement showed non-uniform enhancement of left and right ventricular myocardium. A total of 7 articles published in English were retrieved, and no Chinese literature was found. Twenty-eight cases were reported in the articles plus the patient in this study. Twenty-four mutations were reported worldwide, 18 patients carried homozygous mutations and 10 patients compound heterozygous mutations. Eleven patients showed dilated cardiomyopathy (DCM) at early stage of disease, and 10 of them transitioned to HCM at the disease progression stage. Eight patients presented with HCM at early stage of disease. Nine patients initially exhibited a mixed phenotype of DCM and HCM, and 6 of them eventually progressed to HCM. Electrocardiogram showed prolonged QT interval. Extracardiac features included short stature, special face, cleft palate, webbed neck, joint contracture, and scoliosis, etc. Conclusions: Progressive myocardial hypertrophy is a major feature of ALPK3 gene-related cardiomyopathy with craniofacial-skeletal malformations. Precise diagnosis depends on molecular genetic techniques. More cases should be accumulated for further analysis on the genotype-phenotype correlation and prognosis assessment.