Her family history revealed that she was born from non-consanguineous parents. Her father, a smoker affected with a chronic cough and bronchorrhea with chronic bouts of bronchitis and sibilance, died at the age of 36 from respiratory distress. Four male siblings also died from respiratory distress at the age of 7 days, 3 months, 2 years and 6 years, respectively. A 10-year-old brother was healthy, while a 5-year-old sister was affected with chronic respiratory symptoms (patient 2) and an 11-year-old sister presented with joint and skin symptoms (patient 3). Her mother was suffering from ankylosing spondyloarthritis (ASA). The genealogical tree is shown in Fig. 1.
At admission, physical examination of the index case described a 151-cm-tall girl weighing 49 kg, 37  C of body temperature, 92 heart beats/min, 100/60 mm Hg of blood pressure, 38 breaths/min of respiratory rate, absence of cyanosis, no nail clubbing, a cambered and tympanic chest to percussion, wheezing in the tops, and crackles at lung bases. Chest X-ray showed bronchiectasis. Thoracic computed tomography (CT) confirmed cystic right bronchiectasis of the middle and lingular lobes (Fig. 2a). A functional respiratory assessment (FRA) showed a mixed and diffuse ventilation defect with moderate obstruction, more severe in the small airways.
Blood count detailed 6.6 G/L leucocytes, 3.66 G/L neutrophils, 116 g/L hemoglobin and 362 G/L platelets. A normal sweat test (<50 mmoL/L) excluded the diagnosis of cystic fibrosis. HIV serology was negative, immunoglobulin quantitation was within the normal ranges (IgM: 0.75 g/L, IgA: 3.19 g/L, IgG: 15.32 g/L). Tuberculosis and aspergillar superinfection were also excluded.
Serum protein electrophoresis, performed as a first-line of investigation, showed no alpha-1 globulin peak. Serum AAT quantitative analysis was performed by an immunoturbidimetric test adapted on a multiparametric analyser Konelab 60* (Thermo Fisher Scientific, Cergy Pontoise, France) and revealed undetectable levels (AAT <0.1 g/L). AAT elastase inhibitory activity (EIA), assessed through a kinetic spectrophotometric method, was drastically decreased (3849 Inhibitory Units/L, with 17,500-31,500 IU/L as reference values), in accordance with the very low level of serum AAT.
AAT phenotyping, carried out by isoelectrofocusing electrophoresis (IEF) using ready-to-use agarose gels with immunological detection, revealed a profile without any band, consistent with a very low circulating level of AAT. PI*S and PI*Z-allele-screening by dot blot PCR was negative so a further search for rare variants, by genotyping of the whole coding sequence of SERPINA1 gene by Next Generation Sequencing (NGS), was advised. Genotyping results, according to usual nomenclature, were as follows: a c.775A>T homozygous mutation in exon III of SERPINA1 was characterized. The expected consequence is the generation of a truncated protein with premature stop codon p.(Lys259*), leading to an inactive protein. This Null mutation was previously identified by Zorzetto et al. and recorded as Q0cairo. An additional homozygous c.638T>C sequence variation was also identified, corresponding to a frequently observed variant p.(Val213Ala); this variant was associated with the Q0cairo described by Zorzetto et al.
The same homozygous genotype was identified for patients 2 and 3. The Q0cairo mutation was also detected, in heterozygosis, for the maternal DNA, along with the heterozygous point mutations characterizing the PI*M2 allele, which is generally considered to be without physiological or clinical impact. Nevertheless, an increase in PI*M2 allele frequency has been reported in Tunisian asthmatic patients.
The biochemical and genetic results of the four family members are summarized in Table 1.
The clinical history of the index case revealed recurrent episodes of cough, bronchial congestion and dyspnea from the age of 3 months. At the age of 8, she developed a bronchorrhea with chronic wheezing and bronchial exacerbations.
Moreover, she presented with several episodes of bronchial super-infection that required hospitalization. Bronchoconstriction was chronic with severe exacerbations in autumn/winter that required salbutamol nebulization at home in addition to a bronchodilator, inhaled corticosteroid, leukotriene antagonists and annual influenza vaccination. The patient developed two episodes of right pneumothorax: the first was treated with two thoracic drains, the second was more severe and spread to bilateral sides respecting apexes after a broncho-pleural fistula and a cystic bronchiectasis complication. Intermittent neutropenia was revealed by blood counting.