Partial albinism and immunodeficiency in patients with Hermansky-Pudlak Type II: Introducing 2 novel mutations

Early diagnosis of immunodeficient patients with partial albinism: The role of hair study and peripheral blood smear

BACKGROUND

Primary immunodeficiency diseases (inborn errors of immunity) with partial albinism are a group of autosomal recessive syndromes including Chediak Higashi Syndrome (CHS), Griscelli Syndrome type 2 (GS2), Hermansky-Pudlak Syndromes type 2 and 10 (HPS2, HPS10), Vici syndrome and P14/LAMTOR2 deficiency.

METHODS

Twenty-five patients including 10 CHS, 10 GS2, and 5 HPS2 were evaluated in this study within the last 10 years. Five cases with oculocutaneous albinism (OCA) and 5 healthy subjects without albinism were used as two control groups. Genetic analyses were performed by whole exome or panel sequencing or targeted Sanger sequencing. Subsequently, leukocyte granules in peripheral blood smear and hair shaft were examined as screening tests.

RESULTS

Giant granules were only presented in the leukocytes cytoplasm of 10/10 CHS patients. The uneven cluster of pigments and giant melanin granules in hair samples were observed in 10/10 GS2 and 10/10 CHS patients, respectively. In both 5/5 OCA and 5/5 HPS2 patients, there were regular pigments in the middle of hair shafts. Genetic analyses were performed for all patients, revealing 7 novel variants in LYST gene for CHS patients and 4 novel variants in AP3B1 for HPS2 patients.

CONCLUSION

Receiving hematopoietic stem cell transplantation (HSCT) in a timely manner is crucial in CHS and GS2 patients; therefore, screening tests may provide a vital clue for early diagnosis in these patients. However, the final confirmation of CHS, GS2, and HPS2 disorders is done by genetic assay.

Hemophagocytic Lymphohistiocytosis Associated with Synergistic Defects of AP3B1 and ATM Genes: A Case Report and Literature Review

Hemophagocytic lymphohistiocytosis (HLH) is an overwhelming immune system activation that manifests as hyperinflammation and life-threatening multiple organ failure. However, the clinical manifestations of the systemic inflammatory response in sepsis and fulminant cytokine storm caused by HLH macrophage activation are very similar and difficult to distinguish. HLH triggered by two novel gene defects manifesting with multiorgan dysfunction syndrome (MODS) and distributive shock has not been reported. A 14-year-old male patient was hospitalized with a high fever, his condition deteriorated rapidly, accompanied by cytopenia, shock, and MODS, and he was subsequently transferred to our intensive care unit (ICU) for symptomatic and organ-supportive treatments. Laboratory indicators of cytopenia, hypofibrinogenemia, hypertriglyceridemia, hyperferritinemia, high soluble CD25, low natural killer (NK) cell cytotoxicity, and hemophagocytosis in the bone marrow confirmed the diagnosis of HLH. Molecular genetic analysis revealed that two novel heterozygous gene mutations in AP3B1 (c.3197 C > T) and ATM (c.8077 G > T) might have accounted for the onset. After treatment, the patient’s condition successfully improved. This case report demonstrates the timely determination of underlying triggers and critical care supports (supportive and etiological treatment) of HLH related to the improved outcome.

Detection of Structural Variants by NGS: Revealing Missing Alleles in Lysosomal Storage Diseases

Lysosomal storage diseases (LSDs) are a heterogeneous group of rare multisystem metabolic disorders occurring mostly in infancy and childhood, characterized by a gradual accumulation of non-degraded substrates inside the cells. Although biochemical enzymatic assays are considered the gold standard for diagnosis of symptomatic patients, genotyping is a requirement for inclusion in enzyme replacement programs and is a prerequisite for carrier tests in relatives and DNA-based prenatal diagnosis. The emerging next-generation sequencing (NGS) technologies are now offering a powerful diagnostic tool for genotyping LSDs patients by providing faster, cheaper, and higher-resolution testing options, and are allowing to unravel, in a single integrated workflow SNVs, small insertions and deletions (indels), as well as major structural variations (SVs) responsible for the pathology. Here, we summarize the current knowledge about the most recurrent and private SVs involving LSDs-related genes, review advantages and drawbacks related to the use of the NGS in the SVs detection, and discuss the challenges to bring this type of analysis in clinical diagnostics.

Hermansky-Pudlak syndrome type 2: A rare cause of severe periodontitis in adolescents-A case study

BACKGROUND AND AIMS

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by oculocutaneous albinism (OCA) and platelet storage pool deficiency. The HPS-2 subtype is distinguished by neutropenia, and little is known about its periodontal phenotype in adolescents. AP3B1 is the causative gene for HPS-2. A 13-year-old Chinese girl presented to our department suffering from gingival bleeding and tooth mobility. Her dental history was otherwise unremarkable. Suspecting some systemic diseases as the underlying cause, the patient was referred for medical consultation, a series of blood tests, and genetic tests. In this case study, periodontal status and mutation screening of one HPS-2 case are presented.

METHODS

Blood analysis including a complete blood count (CBC) and glycated hemoglobin levels were measured. Platelet transmission electron microscopy (PTEM) was performed to observe the dense granules in platelets. Whole-exome sequencing (WES) and Sanger sequencing were performed to confirm the pathogenic variants.

RESULTS

A medical diagnosis of HPS-2 was assigned to the patient. Following the medical diagnosis, a periodontal diagnosis of "periodontitis as a manifestation of systemic disease" was assigned to the patient. We identified novel compound heterozygous variants in AP3B1 (NM_003664.4: exon7: c.763C>T: p.Q255^*) and (NM_003664.4: exon1: c.53_56dup: p.E19Dfs^*21) in this Chinese pedigree with HPS-2.

CONCLUSION

This case study indicates the importance of periodontitis as a possible indicator of underlying systemic disease. Systemic disease screening is needed when a young patient presents with unusual, severe periodontitis, as the oral condition may be the first of a systemic abnormality. Our work also expands the spectrum of AP3B1 mutations and further provides additional genetic testing information for other HPS-2 patients.

Refractory Seizure in a Patient With Griscelli Syndrome: A Unique Case With One Mutation and a Novel Deletion

Griscelli syndrome (GS) is a rare syndrome characterized by hypopigmentation, immunodeficiency, and neurological features. The genes Ras-related protein (RAB27A) and Myosin-Va (MYO5A) are involved in this condition's pathogenesis. We present a GS type 1 (GS1) case with developmental delay, hypotonia, and refractory seizures despite multiple medications, which included clobazam, cannabinol, zonisamide, and a ketogenic diet. Lacosamide and levetiracetam were added to the treatment regimen, which decreased the seizures' frequency from 10 per day to five per day. The patient had an MYO5A mutation and, remarkably, a deletion on 18p11.32p11.31. The deletion was previously reported in a patient with refractory seizures and developmental delay. We reviewed all cases of GS that presented with seizures. We reviewed other cases of GS and seizures described in the literature and explored possible seizure mechanisms in GS. Seizure in GS1 seems to be related directly to the MYO5A mutation. The neurological manifestations in GS2 seem to be caused indirectly by the accelerated phase of Hemophagocytic syndrome (HPS), which is characteristic of GS2. By having the MYO5A gene mutation combined with the 18p11.32p11.31 deletion, the prognosis and severity of the patient's condition are poor. This is the first report of GS1 with a deletion in 18p11.32p11.31.