Acromegaloidism with normal growth hormone secretion associated with X-tetrasomy

Approach to the Patient With Pseudoacromegaly

Pseudoacromegaly encompasses a heterogeneous group of conditions in which patients have clinical features of acromegaly or gigantism, but no excess of GH or IGF-1. Acromegaloid physical features or accelerated growth in a patient may prompt referral to endocrinologists. Because pseudoacromegaly conditions are rare and heterogeneous, often with overlapping clinical features, the underlying diagnosis may be challenging to establish. As many of these have a genetic origin, such as pachydermoperiostosis, Sotos syndrome, Weaver syndrome, or Cantú syndrome, collaboration is key with clinical geneticists in the diagnosis of these patients. Although rare, awareness of these uncommon conditions and their characteristic features will help their timely recognition.

Pseudoacromegaly

Individuals with acromegaloid physical appearance or tall stature may be referred to endocrinologists to exclude growth hormone (GH) excess. While some of these subjects could be healthy individuals with normal variants of growth or physical traits, others will have acromegaly or pituitary gigantism, which are, in general, straightforward diagnoses upon assessment of the GH/IGF-1 axis. However, some patients with physical features resembling acromegaly - usually affecting the face and extremities -, or gigantism - accelerated growth/tall stature - will have no abnormalities in the GH axis. This scenario is termed pseudoacromegaly, and its correct diagnosis can be challenging due to the rarity and variability of these conditions, as well as due to significant overlap in their characteristics. In this review we aim to provide a comprehensive overview of pseudoacromegaly conditions, highlighting their similarities and differences with acromegaly and pituitary gigantism, to aid physicians with the diagnosis of patients with pseudoacromegaly.

[Overgrowth with and without obesity: clinical and molecular principles]

Somatic overgrowth is a complex and heterogeneous pathology that is only partially understood, although developments in molecular biology have allowed the discovery of the aetiological basis of some of these conditions. The differential diagnosis of a patient with a possible variant of normality, a chromosomopathy, a dysmorphic syndrome, a metabolic or an endocrine disease is essential. The initial clinical evaluation should include a correct anamnesis and physical examination, as well as complementary laboratory and image analyses that will help to orient the diagnosis. This should include a full blood counts and complete biochemical analysis, determinations of IGF-I, IGFBP-3, free T4, TSH and homocystinuria, as well as a karyotype and an X-ray of the left hand and wrist. These results should be very beneficial in orienting the diagnosis. Additional molecular studies should be performed when a monogenic disease is suspected. Cardiological, ophthalmological, skeletal, psychological and psychiatric studies should be performed if the clinical information and previously mentioned complementary studies so indicate. In this review, the aetiological basis and the diagnostic-therapeutic principles in the most common causes of overgrowth, will be analysed.

[X tetrasomy (48,XXXX karyotype) in a girl with altered behavior]

INTRODUCTION

We report the case of a 14-year-old girl with mental retardation and dysmorphic features referred to child psychiatry because of altered behavior at school.

MATERIAL AND METHODS

Karyotyping (GTG banding), in situ fluorescent hybridization (FISH) and molecular study of parental origin by polymorphic STS were performed.

RESULTS

Genetic study revealed a 48,XXXX karyotype with a maternal origin of the X-tetrasomy. The mechanism was successive non-dysjunction at meiosis I and II.

CONCLUSIONS

The interest of this case lies in the rarity of the chromosomal anomaly and its late diagnosis, leading to a failure to adapt the girl's education to her needs, with consequences for her psyche.

Acromegaly accompanied by Turner syndrome with 47,XXX/45,X/46,XX mosaicism

A 33-year-old woman was hospitalized for examination of edematous laryngopharynx. She was acromegalic. A pituitary adenoma with elevated serum levels of growth hormone (GH) and insulin-like growth factor-I (IGF-I) was detected, indicating acromegaly caused by GH-secreting pituitary adenoma. Multiple pigmented nevi were also noted without overt short stature and cubitus valgus. Chromosome analysis revealed that she had contracted Turner syndrome with 47,XXX/45,X/46,XX mosaicism. Transsphenoidal resection of the tumor decreased serum GH and IGF-I levels, but the edema was not improved. Both premature ovarian failure and hypertension appeared after surgery. This case may indicate the important relationships between GH/IGF-I and Turner syndrome.

Abnormal sex chromosome constitution and longitudinal growth: serum levels of insulin-like growth factor (IGF)-I, IGF binding protein-3, luteinizing hormone, and testosterone in 109 males with 47,XXY, 47,XYY, or sex-determining region of the Y chromosome (SRY)-positive 46,XX karyotypes

CONTEXT

Growth is a highly complex process regulated by the interaction between sex steroids and the GH IGF-axis. However, other factors such as sex chromosome-related genes play independent roles.

AIM

The aim of the study was to evaluate the role of abnormal chromosome constitution for longitudinal growth in relation to reproductive hormones, IGF-I, and IGF binding protein (IGFBP)-3.

SETTING

The study was conducted at an outpatient clinic, Copenhagen University Hospital.

PARTICIPANTS

Participants included 86 47,XXY males, 14 46,XX-males, and nine 47,XYY.

MAIN OUTCOME MEASURES

Standing and sitting height, serum levels of reproductive hormones, IGF-I, and IGFBP-3 were measured.

RESULTS

In boys with 47,XXY and 47,XYY karyotypes, growth was accelerated already in childhood, compared with healthy boys. 46,XX-males were significantly shorter than healthy boys but matched the stature of healthy girls. In 47,XXY sitting height to height ratios were lower than expected, whereas body proportions in 46,XX-males and 47,XYY were normal. In all subjects serum levels of IGF-I and IGFBP-3 were within normal limits. The boys with 46,XX and 47,XXY karyotypes presented with low normal testosterone and elevated LH levels after puberty, whereas the sex hormone secretion of the 47,XYY boys remained normal.

CONCLUSION

We found accelerated growth in early childhood in boys with 47,XXY and 47,XYY karyotypes, whereas 46,XX-males were shorter than controls. These abnormal growth patterns were not reflected in circulating levels of IGF-I and IGFBP-3. The boys with 46,XX and 47,XXY karyotypes developed hypogonadism in puberty, but androgen secretion in 47,XYY boys remained normal. The abnormal stature of these patients may be a result of abnormal gene expression due to the underlying chromosome aberration resulting in excessive expression of growth-related genes.