Unexpected relevant role of gene mosaicism in patients with primary immunodeficiency diseases.

BACKGROUND: Postzygotic de novo mutations lead to the phenomenon of gene mosaicism. The 3 main types are called somatic, gonadal, and gonosomal mosaicism, which differ in terms of the body distribution of postzygotic mutations. Mosaicism has been reported occasionally in patients with primary immunodeficiency diseases (PIDs) since the early 1990s, but its real involvement has not been systematically addressed. OBJECTIVE: We sought to investigate the incidence of gene mosaicism in patients with PIDs. METHODS: The amplicon-based deep sequencing method was used in the 3 parts of the study that establish (1) the allele frequency of germline variants (n = 100), (2) the incidence of parental gonosomal mosaicism in families with PIDs with de novo mutations (n = 92), and (3) the incidence of mosaicism in families with PIDs with moderate-to-high suspicion of gene mosaicism (n = 36). Additional investigations evaluated body distribution of postzygotic mutations, their stability over time, and their characteristics. RESULTS: The range of allele frequency (44.1% to 55.6%) was established for germline variants. Those with minor allele frequencies of less than 44.1% were assumed to be postzygotic. Mosaicism was detected in 30 (23.4%) of 128 families with PIDs, with a variable minor allele frequency (0.8% to 40.5%). Parental gonosomal mosaicism was detected in 6 (6.5%) of 92 families with de novo mutations, and a high incidence of mosaicism (63.9%) was detected among families with moderate-to-high suspicion of gene mosaicism. In most analyzed cases mosaicism was found to be both uniformly distributed and stable over time. CONCLUSION: This study represents the largest performed to date to investigate mosaicism in patients with PIDs, revealing that it affects approximately 25% of enrolled families. Our results might have serious consequences regarding treatment and genetic counseling and reinforce the use of next-generation sequencing-based methods in the routine analyses of PIDs.

Growth and Endocrine Function in Tunisian Thalassemia Major Patients.

ß-thalassemia major (ß-TM) is among the most common hereditary disorders imposing high expenses on health-care system worldwide. The patient's survival is dependent on lifetime blood transfusion which leads to iron overload and its toxicity in various organs including endocrine glands. This article provides an overview of endocrine disorders in beta-TM patients. This single center investigation enrolled 28 ß-TM patients (16 males, 12 females) regularly transfused with packed red cell since early years of life. For each patient were determined: age, sex, number of transfusions received, history of splenectomy and anthropometric parameters. All patients underwent an evaluation of hormonal status including growth, gonadal, thyroid, adrenal cortex, and parathyroid glands. Dual-energy X-ray absorptiometry was used to diagnose low bone mass. Assessment of iron overload status was performed by measuring the serum ferritin concentration and the results of magnetic resonance imaging T2*. Growth retardation was found in 16 of the 28 studied patients (57 %). Thirteen among them had delayed puberty. Spontaneous puberty was achieved in 16 cases. Growth hormone (GH) deficiency was found in 10 cases (35 %). Seventeen among the studied patients (60 %) developed disorders of glucose homeostasis. Subclinical hypothyroidism was found in six patients (21 %). Intensive chelation therapy had allowed the reversibility of this complication in five cases. Adrenal Insufficiency was observed in 9 cases (32%). Hypoparathyroidism has occurred in one case. Ten of the 28 studied patients had low bone mass (35%). Twenty-three of the 28 studied patients (82%) had at least one endocrine complication.

Cutaneous Manifestations of Primary Immunodeficiency Diseases in Tunisian Children.

Skin manifestations are frequent among patients with primary immunodeficiency diseases (PIDs). Their prevalence varies according to the type of immunodeficiency. This review provides the reader with an up-to-date summary of the common dermatologic manifestations of PIDs among Tunisian children. We conducted a prospective study on two hundred and ninety children with immune deficiency. Demographic details (including age, sex, and consanguinity) with personal and family history were recorded. Special attention was paid to cutaneous manifestations. Dermatological involvements were grouped according to the etiology of their most prominent sign. Cutaneous manifestations were found in 164 patients (56.5%). They revealed the diagnosis of PIDs in 71 patients (24.5 %). The mean age at presentation was 21 months. Overall the most prominent cutaneous alterations were infectious. They accounted for 106 cases (36.55%). The most prevalent causes of cutaneous infections were bacterial: 93 cases (32.06%). Immuno-allergic skin diseases were among the common findings in our study. These include eczematous dermatitis found in 62 cases (21.38%). Malignancy related PIDs was seen in a boy with Wiskott Aldrich syndrome. He developed Kaposi's sarcoma at the age of 14 months. Cutaneous changes are common among children with PIDs. In pediatric patients with failure to thrive, chronic refractory systemic manifestations often present in other family members, recurrent cutaneous infections unresponsive to adequate therapy, atypical forms of eczematous dermatitis or unusual features should arouse the suspicion of PIDs and prompt specialized immunologic consultation should be made.