A rare case of male Turner syndrome for penetrating keratoplasty

INTRODUCTION

45,X/46,XY mosaicism, also known as XO/XY mosaicism and mixed gonadal dysgenesis, is a rare disorder of sex development in humans associated with sex chromosome aneuploidy and mosaicism of the Y chromosome.¹ This is called a mosaic karyotype because, like tiles in mosaic floors or walls, there is more than one type of cell.

The clinical manifestations are highly variable, ranging from partial virilisation and ambiguous genitalia at birth, to patients with completely male or female gonads. Most individuals with this karyotype have apparently normal male genitalia, and a minority with female genitalia, with a significant number of individuals showing genital abnormalities or intersex characteristics. A significantly higher than normal number of other developmental abnormalities is also found in individuals with XO/XY mosaicism. Psychomotor development is normal. A rare form of TS has also been described in males.^2,3

CASE REPORT

A 21 year old male diagnosed as TS on preanaesthetic evaluation was posted for tectonic penetrating keratoplasty following a failed graft. The primary corneal opacity was secondary to trauma with a cricket ball. He had undergone two penetrating keratoplasties under local anaesthesia in some other hospital and presented to our institution with a failed graft. This being the third surgery, patient was apprehensive and hence surgery was scheduled under general anaesthesia.

On examination, patient had a short stature and near normal mentation. The secondary sexual characters were not well developed to match his age. Webbing of neck was noted and the neck movements were also restricted. Airway examination revealed a decreased thyromental distance (of just two fingers) and Mallampatti grade was III.

Systemic examination was normal except that he had a soft systolic murmur on auscultation. Haematological results were unremarkable. Chest X-ray was normal. ECG showed sinus bradycardia. Echocardiogram revealed mitral valve prolapse and moderate mitral regurgitation. The specific findings were incurving of both little fingers and notable cubitus valgus. An informed consent was obtained before subjecting the patient to general anaesthesia.

Patient was adequately fasted following universal fasting guidelines. Pre-medication was IM glycopyrrolate. A 20G IV cannula was inserted and routine monitoring were attached (ECG, NIBP, SaO₂ and EtCO₂). Anaesthesia was induced with I.V. Propofol 2 mg/kg and I.V. Fentanyl 1 mg/kg.

As difficult intubation was anticipated the plane of anaesthesia was deepened with bag-mask ventilation using 5% sevoflurane as dial concentration. Laryngoscopy was performed and the presented view was graded as Cormack- Lehane 3. A flexo metallic size 7 (ID) tube was threaded on to the bougie and manipulated under epiglottis. Intubation was successful in first attempt. The correct placement of the tube was confirmed by auscultation and capnography. Patient was paralyzed with vecuronium bromide (1 mg/kg) and volatile of choice was desflurane. Patient remained stable throughout the intraoperative period. The duration of the surgery was about two hours. At the end of the surgery the residual neuromuscular paralysis was reversed and patient was extubated completely awake.

DISCUSSION

45,X/46,XY mosaicism is associated with a broad spectrum of phenotypes ranging from apparently normal male development to individuals with incomplete sexual determination and clinical signs of Turner Syndrome in both males and females. The most common presentation among individuals with a 45,X/46,XY karyotype is sexual ambiguity accounting for approximately 60% of cases, while the least common category of 45,X/46,XY patients consist of those with bilaterally descended testes found in 11-12%.

In a normal situation, all the cells in an individual will have 46 chromosomes with one being X and one Y or with two Xs. However, during this complicated early copying process (DNA replication and cell division), one chromosome may be lost. In 45,X/46,XY, most or all of Y chromosome is lost in one of the newly created cells. All the cells then made from this cell will lack the Y chromosome. Those cells created from these cells that have not lost the Y chromosome will be XY.⁴ The 46,XY cells will continue to multiply at the same time as the 45,X cells multiply. The embryo, then the fetus and then the baby will have what is called a 45,X/46,XY constitution. This is called a mosaic karyotype, because like tiles in mosaic floors or walls, there is more than one type of cell.

There are many chromosomal variations that cause the 45,X/46,XY karyotype, including malformation (isodicentricism) of the Y chromosomes, deletions of Y chromosome or translocations of Y chromosome segments.⁵ These rearrangements of the Y chromosome can lead to partial expression of the SRY gene which may lead to abnormal genitals and testosterone levels.

Although similar in some ways to true hermaphroditism, the conditions can be distinguished histologically and by karyotyping.⁶ The observable characteristics (phenotype) of this condition are highly variable, ranging from gonadal dysgenesis in males, to Turner-like females and phenotypically normal males.^7,8 The most common presentation of 45,X/46,XY karyotype is phenotypically normal male, next being genital ambiguity.⁹

The male turner syndrome is one of the rarest presentations and with its complexities calls for a through anaesthetic planning.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

REFERENCES

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