[Solved]-Show only discontinuous points in Highcharts line graph-Highcharts

You can enable markers for individual data points:

    series: [{
        data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, NaN, {
            y: 54.4,
            marker: {
                enabled: true
            }
        }]
    }]

Live demo: https://jsfiddle.net/BlackLabel/2prxc63m/

API Reference: https://api.highcharts.com/highcharts/series.line.data.marker.enabled