Clinical heterogeneity in a family with DKC1 mutation, dyskeratosis congenita and Hoyeraal-Hreidarsson syndrome in first cousins

Pulmonary fibrosis may begin in infancy: from childhood to adult interstitial lung disease

BACKGROUND

Childhood interstitial lung disease (chILD) encompasses a group of rare heterogeneous respiratory conditions associated with significant morbidity and mortality. Reports suggest that many patients diagnosed with chILD continue to have potentially progressive or fibrosing disease into adulthood. Over the last decade, the spectrum of conditions within chILD has widened substantially, with the discovery of novel entities through advanced genetic testing. However, most evidence is often limited to small case series, with reports disseminated across an array of subspecialty, clinical and molecular journals. In particular, the frequency, management and outcome of paediatric pulmonary fibrosis is not well characterised, unlike in adults, where clear diagnosis and treatment guidelines are available.

METHODS AND RESULTS

This review assesses the current understanding of pulmonary fibrosis in chILD. Based on registry data, we have provisionally estimated the occurrence of fibrosis in various manifestations of chILD, with 47 different potentially fibrotic chILD entities identified. Published evidence for fibrosis in the spectrum of chILD entities is assessed, and current and future issues in management of pulmonary fibrosis in childhood, continuing into adulthood, are considered.

CONCLUSIONS

There is a need for improved knowledge of chILD among pulmonologists to optimise the transition of care from paediatric to adult facilities. Updated evidence-based guidelines are needed that incorporate recommendations for the diagnosis and management of immune-mediated disorders, as well as chILD in older children approaching adulthood.

A Novel Variant and a Missense Variant Identified in the DKC1 Gene in Three Chinese Familieswith Dyskeratosis Congenita

Purpose

Dyskeratosis congenita (DC) is an inherited telomere biology disorder characterized clinically by mucocutaneous triad of reticulate hyperpigmentation, nail changes and oral leukoplakia. Bone marrow failure, pulmonary fibrosis and malignancies are the mainly life-threatening causes. There are X-linked recessive, autosomal dominant and autosomal recessive patterns of DC. DKC1 is the most common pathogenic mutation gene responsible for X-linked DC, and it encodes a protein, dyskerin, which is a component of telomerase holoenzyme complex essential for telomere maintenance. Patients with DC have very short telomeres, but the precise pathogenic mechanism remains unclear. This study aimed to identify the causative mutations in the DKC1 gene in three Chinese families with the X-linked form of DC.

Patients and Methods

Three Chinese families with DC were included in this study. Whole exome sequencing and Sanger sequencing were performed to clarify the mutation of DKC1 gene. Measurement of relative telomere length through qPCR. Predictions of protein structure and function were performed using bioinformatics tools, including I-TASSER, Polyphen-2 and SIFT.

Results

There were four males with DC and a female carrier in three Chinese pedigrees. The novel mutation c.92A>C (p. Q31P) and the missense mutation c.1058C>T (p. A353V) in DKC1 were identified. Both mutations locally changed the structure of dyskerin. Variant Q31P and A353V were predicted to have “deleterious” and “natural” effects on the function of dyskerin, respectively.

Conclusion

The novel variant and missense variant detected in the DKC1 gene improve our understanding of DC and broaden the mutation spectrum of the DKC1 gene.

Revesz syndrome revisited

Background

Revesz syndrome (RS) is an extremely rare variant of dyskeratosis congenita (DKC) with only anecdotal reports in the literature.

Methods

To further characterize the typical features and natural course of the disease, we screened the English literature and summarized the clinical and epidemiological features of previously published RS cases. In addition, we herein describe the first recorded patient in central Europe.

Results

The literature review included 18 children. Clinical features are summarized, indicating a low prevalence of the classical DKC triad. All patients experienced early bone marrow failure, in most cases within the second year of life (median age 1.5 years; 95% CI 1.4–1.6). Retinopathy occurred typically between 6 and 18 months of age (median age 1.1 years; 95% CI 0.7–1.5). The incidence of seizures was low and was present in an estimated 20% of patients. The onset of seizures was exclusively during early childhood. The Kaplan–Meier estimate of survival was dismal (median survival 6.5 years; 95% CI 3.6–9.4), and none of the patients survived beyond the age of 12 years. Stem cell transplantation (SCT) was performed in eight children, and after a median of 22 months from SCT four of these patients were alive at the last follow up visit.

Conclusion

RS is a severe variant of DKC with early bone marrow failure and retinopathy in all patients. Survival is dismal, but stem cell transplantation may be performed successfully and might improve prognosis in the future.

Dyskeratosis congenita: a literature review

Dyskeratosis congenita is a rare hereditary disease that occurs predominantly in males and manifests clinically as the classic triad of reticulate hyperpigmentation, nail dystrophy and leukoplakia. It increases the risk of malignancy and other potentially lethal complications such as bone marrow failure, lung and liver diseases. Mutations in 19 genes are associated with dyskeratosis congenita, and a fifth of the pathogenic mutations are found in DKC1, the gene coding for dyskerin. This review aims to address the clinical and genetic aspects of the disease.

Pure Red Cell Aplasia (PRCA) and Cerebellar Hypoplasia as Atypical Features of Polyglandular Autoimmune Syndrome Type I (APS-1): Two Sisters With the Same AIRE Mutation but Different Phenotypes

The polyglandular autoimmune syndrome type I is a rare hereditary autosomal recessive disease. We describe a child with the classic triad of the disease and her sister with pure red cell aplasia and cerebellar hypoplasia. The latter received two haematopoietic stem cell transplantations, complicated by an acute disseminated encephalomyelitis.