Humza Yousaf is facing a new test to his leadership in the wake of the publication of the Cass Review which examined gender services for children and young people.

The study, published last week, analysed the evidence - or lack thereof - for prescribing puberty blockers and hormone treatments to gender-questioning children and teenagers and advised "extreme caution" over their use for under-18s due to the lack of long-term evidence for their effects.

It immediately prompted a debate with some figures in the SNP, including the MP Joanna Cherry, demanding that the Scottish Government implement the advice in the NHS in Scotland, while the Scottish Greens MSP Maggie Chapman, said her party would oppose any moves to raise the age that such drugs can be prescribed on the NHS.

In a letter to Dr Gregor Smith, the chief medical officer, Ms Cherry said: “The prescription of puberty blockers places gender questioning children and young people on a medicalised pathway which has life-long implications. The NHS in Scotland has been slow to react to emerging evidence of the harm of these practices and all too often relies on international best practice as a catch all to avoid difficult conversations.”

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She added: “The publication of the Cass Review should be an urgent wake-up call that services for children and young people must be urgently re-designed and puberty blockers removed from use in Scotland.”

But writing on X, formerly Twitter, Ms Chapman, the Scottish Greens equalities spokeswoman, noted: "A short, initial response to the Cass Report.

"Trans Healthcare is vital to protecting and supporting the rights and lives of trans people. Scottish Greens will oppose any moves to increase the age of accessing gender affirming care to 25.

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"Trans rights are human rights. We must ensure trans people are able to access the care they need in a timely & compassionate manner. It’s clear that gender affirming care plays a vital role in supporting & protecting trans people …We would oppose any moves to increase the minimum age to 25 to receive such care."

For its part the Scottish Government has not yet said how it will respond saying last week it was in the process of considering the Cass Review's findings.

But some on the SNP backbenches are getting twitchy.

The issue of young people, gender self-identification and the role of medicine in the process or not was at the heart of the Scottish Government's most internally contested reforms.

The now shelved gender recognition reform bill included the proposal to lower the age from 18 to 16 to allow someone to apply for a gender certificate and to remove the need for a doctor to approve the application.

It caused the biggest ever SNP backbench rebellion with nine MSPs failing to back the government's legislation when it was voted on in Holyrood at its first key parliamentary stage back in October 2022. 

Some observers believe the issue of gender self-identification and the separate row of transwomen prisoners being held in women's prisons - which came to a head with the Isla Bryson double rape case - contributed to the demise of Nicola Sturgeon as SNP leader and First Minister.

Mr Yousaf will have to tread very carefully if he is to avoid reawakening these SNP backbench tensions.

Over the weekend, it was reported that his response to the Cass report could be "pivotal" in whether this group of SNP MSPs spark a rebellion over the leadership’s co-operation with the Scottish Greens, who are strong supporters of gender self-identification.

One SNP MSP told Scotland on Sunday that "the response to the Cass report may be pivotal”, with backbenchers looking “to what extent the SNP will attempt to appease the Greens rather than act in the best interests of Scottish children”.

Any backbench rebellion would come at a difficult time for the First Minister whose government has faced a series of serious problems over the past year, including a backlash against its Hate Crime Act, further turmoil amid additional delays to already late and over-budget ferries, a challenging budget that included tax rises and public service cuts and questions over how ministers conducted business during the pandemic.

Separately, a police investigation into the SNP’s finances that resulted in Ms Sturgeon being arrested, questioned and released without charge has hung over the party of government.

The question on the minds of many observers would inevitably be 'would Mr Yousaf's leadership survive a new full blown rebellion ahead of an election?

With the stakes so high for the First Minister, his silence to date on the Cass review is therefore not surprising.

But with Ms Cherry demanding a swift answer to her call for a ban on puberty blockers for under 18s, it's not a matter that's going to fade from public attention in the coming weeks.

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