A novel AAAS gene mutation (p.R194X) in a patient with triple A syndrome

Triple-A syndrome: a wide spectrum of adrenal dysfunction

OBJECTIVE

Triple-A or Allgrove syndrome is an autosomal recessive disorder due to mutations in the AAAS gene, which encodes a nucleoporin named ALADIN. It is characterized by a classical clinical triad: alacrima, achalasia and adrenal insufficiency, the canonic symptoms that are associated with progressive peripheral neuropathy. Only a few cohorts have been reported. The objective of the present study was to characterize the various spectra of adrenal function in Triple-A patients.

METHODS

A retrospective clinical and biological monitoring of 14 patients (10 families) was done in a single multidisciplinary French center. All had AAAS gene sequenced and adrenal function evaluation.

RESULTS

Nine different AAAS mutations were found, including one new mutation: c.755G>C, p.(Trp252Ser). Regarding adrenal function, defects of the zona fasciculata and reticularis were demonstrated by increased basal ACTH levels and low DHEAS levels in all cases regardless of the degree of glucocorticoid deficiency. In contrast, mineralocorticoid function was always conserved: i.e., normal plasma renin level associated with normal aldosterone level. The main prognostic feature was exacerbation of neuropathy and cognitive disorders.

CONCLUSIONS

These data suggest that, in Triple-A patients, adrenal function can be deficient, insufficient or compensated. In our cohort after the first decade of life, there does not appear to be any degradation of adrenal function over time. However, patients with compensated adrenal function should be informed and educated to manage a glucocorticoid replacement therapy in case of stressful conditions, with no need for systematic long-term treatment.

Phenotype-genotype spectrum of AAA syndrome from Western India and systematic review of literature

OBJECTIVE

To study genotype-phenotype spectrum of triple A syndrome (TAS).

METHODS

Retrospective chart analysis of Indian TAS patients (cohort 1, n = 8) and review of genotyped TAS cases reported in world literature (cohort 2, n = 133, 68 publications).

RESULTS

Median age at presentation was 4.75 years (range: 4-10) and 5 years (range: 1-42) for cohorts 1 and 2, respectively. Alacrima, adrenal insufficiency (AI), achalasia and neurological dysfunction (ND) were seen in 8/8, 8/8, 7/8 and 4/8 patients in cohort 1, and in 99, 91, 93 and 79% patients in cohort 2, respectively. In both cohorts, alacrima was present since birth while AI and achalasia manifested before ND. Mineralocorticoid deficiency (MC) was uncommon (absent in cohort 1, 12.5% in cohort 2). In cohort 1, splice-site mutation in exon 1 (p.G14Vfs*45) was commonest, followed by a deletion in exon 8 (p.S255Vfs*36). Out of 65 mutations in cohort 2, 14 were recurrent and five exhibited regional clustering. AI was more prevalent, more often a presenting feature, and was diagnosed at younger age in T group (those with truncating mutations) as compared to NT (non-truncating mutations) group. ND was more prevalent, more common a presenting feature, with later age at onset in NT as compared to T group.

CONCLUSION

Clinical profile of our patients is similar to that of patients worldwide. Alacrima is the earliest and most consistent finding. MC deficiency is uncommon. Some recurrent mutations show regional clustering. p.G14Vfs*45 and p.S255Vfs*36 account for majority of AAAS mutations in our cohort. Phenotype of T group differs from that of NT group and merits future research.

Low bone mineral density for age/osteoporosis in triple A syndrome-an overlooked symptom of unexplained etiology

Triple A syndrome (alacrima, achalasia, adrenal failure, progressive neurodegenerative disease) is caused by mutations in the AAAS gene which encodes the protein alacrima achalasia adrenal insufficiency neurologic disorder (ALADIN). Our investigation suggests that low bone mineral density (BMD) for age/osteoporosis could be a common but overlooked symptom of unexplained etiology in this rare multisystemic disease.

INTRODUCTION

The purpose of this study is to evaluate incidence and etiology of BMD for age/osteoporosis, a possibly overlooked symptom in triple A syndrome.

METHODS

Dual-energy X-ray absorptiometry (DXA) of the femoral neck, total hip, lumbar spine, and radius, bone turnover markers, minerals, total alkaline phosphatase (ALP), 25-hydroxy vitamin D (25-OHD), 1,25-dihydroxy vitamin D (1,25-OH2D), intact parathyroid hormone (PTH), and adrenal androgens (dehydroepiandrosterone sulfate (DHEAS) and androstenedione) were measured in five male and four female patients.

RESULTS

At time of diagnosis, low BMD for age was suspected on X-ray in seven of nine patients aged 2-11 years (not performed in two patients); normal levels of minerals and ALP were found in nine patients and low levels of adrenal androgens in eight patients (not measured in one patient). Reevaluation 5-35 years after introduction of 12 mg/m(2)/day hydrocortisone showed low BMD for age in two children, osteopenia in one, and osteoporosis in six adults. Normal levels of minerals, ALP, PTH, 1,25-OH2D, procollagen type 1, crosslaps, and osteocalcin were found in all patients. Low levels of adrenal androgens were found in all and 25OHD deficiency in six patients. Body mass index was <25 % for age and sex in eight of nine patients.

CONCLUSION

Low BMD for age/osteoporosis in our patients probably is not a result of glucocorticoid therapy but could be the consequence of low level of adrenal androgens, neurological impairment causing physical inactivity, inadequate sun exposure, and protein malnutrition secondary to achalasia. Considering ubiquitous ALADIN expression, low BMD/osteoporosis may be a primary phenotypic feature of the disease. Besides optimizing glucocorticoid dose, physical activity, adequate sun exposure, appropriate nutrition, and vitamin D supplementation, therapy with DHEA should be considered.

Long-term clinical follow-up and molecular genetic findings in eight patients with triple A syndrome

The triple A syndrome (Allgrove syndrome, OMIM #231550) is caused by autosomal recessively inherited mutations in the AAAS gene on chromosome 12q13 encoding the nuclear pore protein ALADIN. This multisystemic disease is characterised by achalasia, alacrima, adrenal insufficiency and neurological impairment. We analyse long-term clinical follow-up and results of sequencing of the AAAS gene in eight patients with triple A syndrome aged from 2 to 35 years. At the time of diagnosis, all patients presented with alacrima, neurological dysfunction, dermatological abnormalities, seven of them with adrenal insufficiency and five of them with achalasia. Sequencing of the AAAS gene identified the p.S263P mutation in five of eight patients, supporting the hypothesis that this mutation is a founder mutation in Slavic population. One of the patients is homozygous for the p.S263P mutation, two are compound heterozygous for the p.S263P and the p.G14fs mutation, two are compound heterozygous for the p.S263Pro mutation and p.S296Y mutation, two are compound heterozygous for the p.G14fs and the p.Q387X mutations and one is homozygous for the p.Q387X mutation. In the course of the follow-up time of 4-29 years, progression of existing and appearance of new symptoms developed. Although severe, many of these symptoms presented in all six young adult patients are often overlooked or neglected: postural hypotension with blurred vision and syncope, hyposalivation resulting with complete edentulosis, talocrular contractures with permanent walking difficulties and erectile dysfunction in male patients. Triple A syndrome is a progressive debilitating disorder which may seriously affect quality of life and even be life-threatening in patients with severe neurological impairment.

CONCLUSION

Long-term follow-up of patients with triple A syndrome revealed a variety of the clinical features involving many systems. Progressive natural course of the disease may seriously affect quality of life and even be life-threatening in patients with severe neurological impairment.

Neurological features in adult Triple-A (Allgrove) syndrome

Triple-A or Allgrove syndrome is a rare multisystem disease classically associated with esophageal achalasia, adrenal insufficiency and alacrima. Here, we describe the poorly understood neurological characteristics often associated with this condition, through the clinical and electrophysiological analysis of eight patients. All patients were genetically confirmed and had a mutation in the ALADIN gene. They all displayed a classical picture of Triple-A syndrome: all suffered from achalasia and alacrima and half of them from adrenal insufficiency. However, all harbored a neurological picture characterized by a recognizable pattern of peripheral neuropathy. Other neurological features included cognitive deficits, pyramidal syndrome, cerebellar dysfunction, dysautonomia, neuro-ophthalmological signs and bulbar and facial symptoms. This neurological picture was prominent in all patients and misled the initial diagnosis in six of them, which had a late onset. We then review the previous neurological reports of this disease, to improve the understanding of this rare condition. Diagnosis of late-onset Triple-A syndrome is difficult when the clinical picture is mainly neurological and when endocrine or gastrointestinal signs are minor. The characteristics of the peripheral neuropathy, among other neurological signs, can be of help.

Two siblings with triple A syndrome and novel mutation presenting as hereditary polyneuropathy

The clinical and molecular data on triple A syndrome in two siblings (girl 3.5 years and boy 5.5 years at presentation) with early onset of neurological dysfunction are described. Both patients showed delayed developmental milestones and neurological dysfunctions (motor and sensory demyelinating neuropathy, marked hyperreflexia, calves hypothrophy, pes cavus, gait disturbance) in early childhood, when erroneously diagnosed with hereditary polyneuropathy, most likely Charcot-Marie-Tooth disease. After a severe adrenal crisis in the younger sister at the age of 3 years, the older brother aged 5.5 years was also evaluated and latent adrenal insufficiency was discovered. As both of the siblings had alacrima, hyperkeratosis of palms, cutis anserina, and nasal speech, diagnosis of triple A syndrome was considered. Sequencing of the AAAS gene detected a compound heterozygous mutation consisting of a novel mutation p.Ser296Tyr (c.887C>A) in exon 9 and a previously described p.Ser263Pro (c.787T>C) missense mutation in exon 8 in both siblings. In conclusion, triple A syndrome should be considered in patients presenting with early neurological dysfunction and developmental delay. Alacrima as the earliest and most consistent clinical sign should be investigated by Schirmer test. Patients should be regularly tested for adrenal dysfunction to prevent life-threatening adrenal crises.

Common variants in the region around Osterix are associated with bone mineral density and growth in childhood

Peak bone mass achieved in adolescence is a determinant of bone mass in later life. In order to identify genetic variants affecting bone mineral density (BMD), we performed a genome-wide association study of BMD and related traits in 1518 children from the Avon Longitudinal Study of Parents and Children (ALSPAC). We compared results with a scan of 134 adults with high or low hip BMD. We identified associations with BMD in an area of chromosome 12 containing the Osterix (SP7) locus, a transcription factor responsible for regulating osteoblast differentiation (ALSPAC: P = 5.8 x 10(-4); Australia: P = 3.7 x 10(-4)). This region has previously shown evidence of association with adult hip and lumbar spine BMD in an Icelandic population, as well as nominal association in a UK population. A meta-analysis of these existing studies revealed strong association between SNPs in the Osterix region and adult lumbar spine BMD (P = 9.9 x 10(-11)). In light of these findings, we genotyped a further 3692 individuals from ALSPAC who had whole body BMD and confirmed the association in children as well (P = 5.4 x 10(-5)). Moreover, all SNPs were related to height in ALSPAC children, but not weight or body mass index, and when height was included as a covariate in the regression equation, the association with total body BMD was attenuated. We conclude that genetic variants in the region of Osterix are associated with BMD in children and adults probably through primary effects on growth.