Growth hormone deficiency in mitochondrial cytopathy

Kearns-Sayre Syndrome: A Case Report and Review

In 1958, Kearns and Sayre described a multisystem entity, now known as Kearns-Sayre syndrome (KSS). The syndrome is defined as exhibiting a triad of thus far unexplained degenerative conditions: progressive external ophthalmoplegia, retinal pigmentary degeneration, and heart block. Commonly accompanying findings include cerebellar dysfunction and CSF protein levels above 100 mg/dl. Symptoms usually appear in early childhood, but the onset has been seen occasionally in young adults. KSS is a mitochondrial disorder that occurs rarely; the actual incidence is unknown. Ocular findings consist of bilateral ptosis, chronic progressive external ophthalmoplegia, and pigmentary retinopathy. Corneal clouding and optic neuritis are infrequent.

We herein report a classic case of Kearns Sayre syndrome and discuss the findings.

Mitochondrial disease and endocrine dysfunction

Mitochondria are critical organelles for endocrine health; steroid hormone biosynthesis occurs in these organelles and they provide energy in the form of ATP for hormone production and trafficking. Mitochondrial diseases are multisystem disorders that feature defective oxidative phosphorylation, and are characterized by enormous clinical, biochemical and genetic heterogeneity. To date, mitochondrial diseases have been found to result from >250 monogenic defects encoded across two genomes: the nuclear genome and the ancient circular mitochondrial genome located within mitochondria themselves. Endocrine dysfunction is often observed in genetic mitochondrial diseases and reflects decreased intracellular production or extracellular secretion of hormones. Diabetes mellitus is the most frequently described endocrine disturbance in patients with inherited mitochondrial diseases, but other endocrine manifestations in these patients can include growth hormone deficiency, hypogonadism, adrenal dysfunction, hypoparathyroidism and thyroid disease. Although mitochondrial endocrine dysfunction frequently occurs in the context of multisystem disease, some mitochondrial disorders are characterized by isolated endocrine involvement. Furthermore, additional monogenic mitochondrial endocrine diseases are anticipated to be revealed by the application of genome-wide next-generation sequencing approaches in the future. Understanding the mitochondrial basis of endocrine disturbance is key to developing innovative therapies for patients with mitochondrial diseases.

Efficacy of growth hormone therapy in Kearns-Sayre syndrome: the KIGS experience

Kearns-Sayre syndrome (KSS) is characterized by external ophthalmoplegia, retinal pigmentation and cardiac conduction defects due to mitochondrial DNA (mtDNA) deletions. Short stature and growth hormone (GH) deficiency have been reported in KSS, but data on GH treatment is limited. We describe the clinical presentation, phenotype evolution, and response to GH in a patient with KSS and report data on eight additional KSS patients from the KIGS database. Our patient with KSS and GH deficiency achieved a final adult height at -0.8 SDS. In the KIGS database GH treatment resulted in mean improvement in height from -3.9 to -2.9 SDS in patients with KSS. Two patients did not show growth improvement. Our data shows improvement in height SDS in our patient and mixed results in eight additional patients from the KIGS database after treatment with GH. Heterogeneity in responsiveness may relate to presence of GH deficiency or severity of underlying mitochondrial dysfunction.

A novel mitochondrial DNA deletion in a patient with Kearns-Sayre syndrome: a late-onset of the fatal cardiac conduction deficit and cardiomyopathy accompanying long-term rGH treatment

Background

Kearns-Sayre Syndrome (KSS) is a multisystem disorder caused by a dysfunction of the oxidative phosphorylation system within mitochondria. Mitochondrial DNA (mtDNA) rearrangements are a key molecular feature of this disease, which manifest a broad phenotypic spectrum.

Case presentation

Here, we present a boy with KSS whose symptoms included cardiac conduction deficit, cardiomyopathy and growth hormone (GH) deficiency. The patient showed typical symptoms for KSS from early childhood (chronic progressive external ophthalmoplegia, retinopathy, short stature). Long-range PCR analysis disclosed a 7663-base pair heteroplasmic deletion in the mtDNA encompassing nucleotides 6340–14003. At 12 years of age, GH deficiency was recognized and recombinant growth hormone (rGH) therapy was started. At 15 years of age, a complete atrioventicular block was diagnosed and the patient received a pacemaker. During the following 6 months, progressive deterioration of the left ventricle was observed and an echocardiogram showed features of dilated cardiomyopathy. The rGH treatment was then discontinued at a final height of 163 cm. Unfortunately, due to multi-organ insufficiency and inflammation, the patient died at the age of 18 years.

Conclusions

The response to rGH therapy in the patient was very satisfactory. The large mtDNA deletion had no apparent impact on the response to rGH. Cardiac disturbances occurred as part of the syndrome and were not related to rGH therapy; however, the progression of the disease led to death.

Kearns-Sayre syndrome presenting as isolated growth failure

Failure to thrive arises from a heterogeneous group of paediatric disorders including defects in energy metabolism such as mitochondrial diseases. Illustrating this, we describe a girl with poor growth who eluded diagnosis until she developed characteristics of Kearns-Sayre syndrome. Her history emphasises that defects of energy metabolism can present as isolated growth failure.

Manometric characteristics of cervical dysphagia in a patient with the Kearns-Sayre syndrome

The manometric findings of deglutitive pharyngoesophageal function in a patient with the Kearns-Sayre syndrome and cervical dysphagia are described. These findings indicate that striated muscles of the pharynx, upper esophageal sphincter (UES), and proximal esophagus are involved. Near absence of pharyngeal peristalsis, abnormally low UES resting pressure, and absence of proximal esophageal peristalsis characterize the manometric findings in this patient. It is conceivable that in mild cases, a combination of various degrees of severity of the above findings may exist.

Endocrine dysfunction in Kearns-Sayre syndrome

Kearns-Sayre syndrome (KSS) is a form of mitochondrial myopathy in which specific clinical features, namely progressive external ophthalmoplegia, pigmentary retinal degeneration and cardiac conduction defects, occur. KSS has also been associated with a variety of endocrine and metabolic disorders, in particular short stature, gonadal failure, diabetes mellitus, thyroid disease, hyperaldosteronism, hypomagnesaemia, and bone, tooth and calcification abnormalities. A case is described exhibiting all of these features. A survey of the literature was conducted to determine the prevalence of these conditions among reported cases. Cases with hypoparathyroidism were considered separately to see if they constituted a distinct subgroup with multiple endocrine dysfunction. Short stature was common, being documented in 38% of cases. Gonadal dysfunction before or after puberty was also common (20% of cases) and affected both sexes equally. Diabetes mellitus was recorded in 13% of cases, half of which required insulin. Thyroid disease, hyperaldosteronism and hypomagnesaemia were uncommon but were probably not looked for in many cases. Bone or tooth abnormalities and calcification of the basal ganglia were found both in those with and without hypoparathyroidism. While endocrine and metabolic dysfunction was found more commonly in those with hypoparathyroidism this is likely to be due to increased recognition rather than increased prevalence. No evidence of an autoimmune polyendocrine syndrome including hypoparathyroidism was found.

Transient postictal cortical blindness

An 8-year-old boy with insulin-dependent diabetes mellitus and a seizure disorder demonstrated transient visual loss after severe seizure activity. The role of hypoglycemia in relation to his transient cortical blindness remains indeterminate. The nature of the cortical involvement, the rate of visual recovery, and prior reports of postictal phenomena emphasize the relatively benign nature of this condition in children.

Hyperglycemic acidotic coma and death in Kearns-Sayre syndrome

This paper presents the clinical and metabolic findings in two young boys with long-standing Kearns-Sayre syndrome. Following short exposure to oral prednisone, both boys developed lethargy, increasing somnolence, polydipsia, polyphagia, and polyuria. Both presented in the emergency room with profound coma, hypotension, severe hyperglycemia, and acidosis. Nonketotic lactic acidosis was present in one and ketosis without a known serum lactate level was present in the other. Respiratory failure rapidly ensued and both patients expired in spite of efforts at resuscitation. We believe these two cases represent a newly described and catastrophic metabolic-endocrine failure in the Kearns-Sayre syndrome.